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Contains fulltext : 241347.pdf (Publisher’s version ) (Closed access) Asparaginase (ASNase) therapy has been a mainstay of acute lymphoblastic leukemia (ALL) protocols for decades and shows promise in the treatment of a variety of other cancers. To improve the efficacy of ASNase treatment, we used a CRISPR/Cas9-based screen to identify actionable signaling intermediates that improve the response to ASNase. Both genetic inactivation of Bruton's tyrosine kinase (BTK) and pharmacological inhibition by the BTK inhibitor ibrutinib strongly synergize with ASNase by inhibiting the amino acid response pathway, a mechanism involving c-Myc-mediated suppression of GCN2 activity. This synthetic lethal interaction was observed in 90% of patient-derived xenografts, regardless of the genomic subtype. Moreover, ibrutinib substantially improved ASNase treatment response in a murine PDX model. Hence, ibrutinib may be used to enhance the clinical efficacy of ASNase in ALL. This trial was registered at www.clinicaltrials.gov as # NCT02884453.

Bortezomib (BTZ) was recently evaluated in a randomized phase 3 clinical trial by the Children’s Oncology Group (COG) that compared standard chemotherapy (cytarabine, daunorubicin, and etoposide [ADE]) vs standard therapy with BTZ (ADEB) for de novo pediatric acute myeloid leukemia (AML). Although the study concluded that BTZ did not improve outcome overall, we examined patient subgroups benefiting from BTZ-containing chemotherapy using proteomic analyses. The proteasome inhibitor BTZ disrupts protein homeostasis and activates cytoprotective heat shock responses. Total heat shock factor 1 (HSF1) and phosphorylated HSF1 (HSF1-pSer326) were measured in leukemic cells from 483 pediatric patients using reverse phase protein arrays. HSF1-pSer326 phosphorylation was significantly lower in pediatric AML compared with CD34+ nonmalignant cells. We identified a strong correlation between HSF1-pSer326 expression and BTZ sensitivity. BTZ significantly improved outcome of patients with low-HSF1-pSer326 with a 5-year event-free survival of 44% (ADE) vs 67% for low-HSF1-pSer326 treated with ADEB (P = .019). To determine the effect of HSF1 expression on BTZ potency in vitro, cell viability with HSF1 gene variants that mimicked phosphorylated (S326A) and nonphosphorylated (S326E) HSF1-pSer326 were examined. Those with increased HSF1 phosphorylation showed clear resistance to BTZ vs those with wild-type or reduced HSF1-phosphorylation. We hypothesize that HSF1-pSer326 expression could identify patients who benefit from BTZ-containing chemotherapy.

Background: Intensive chemotherapy has improved complete remission (CR) rates in T-ALL/LBL. However, long-term overall survival (OS) continues to be suboptimal at about 50%. Nelarabine (NEL) is active in relapsed/refractory T-ALL. PEG-asparaginase (PEG) containing regimens have demonstrated significant activity in the pediatric population (Dunsmore et al. COG AALL0434. J Clin Oncol. 2018 Abstr #10500). We hypothesized that incorporating NEL and PEG in the frontline setting may further improve outcomes in adult T-ALL/LBL (NCT00501826). We had previously reported on the addition of nelarabine to the hyper-CVAD regimen (Abaza Y, Am J Hematol. 2018). Here, we report outcomes with the addition of PEG and longer follow-up. Methods Pts with T-ALL/LBL, either newly diagnosed or minimally treated (no CR with 1 cycle or CR after ≤2 cycles of induction) were eligible. Pts needed to have ECOG performance status (PS) ≤3, creatinine ≤2 mg/dL, bilirubin ≤2 mg/dL and ALT/AST ≤4 x ULN. The objectives were to determine safety, CR rate, progression-free survival (PFS), and OS with this combination. Pts received 8 cycles of with HCVAD (odd cycles 1,3,5,7) alternating with methotrexate (MTX) and cytarabine (ara-C; even cycles 2,4,6,8) at approximately 3-week intervals. Initially pts received NEL 650 mg/m2 IV daily for 5 days after 8 cycles as above. After enrollment of 30 pts, protocol was amended to deliver the 2 courses of NEL after cycle 4 and 5 of therapy in an attempt to reduce risk of early relapse. After enrollment of 79 pts, PEG (1500 IU/m2 IV capped at 3750 IU for pts ≤60 yrs and at 2000 IU for pts >60 yrs) was added to NEL courses on day 5. After completion of intensive phase, pts received 30 months of POMP maintenance (6-MP, vincristine, MTX, prednisone) with NEL/PEG replacing cycle 6 and 7 of POMP as early intensification. Late intensification consisted of MTX/PEG replacing cycle 18 and HCVAD replacing cycle 19 of POMP. CNS prophylaxis included 8 intrathecal doses of MTX alternating with ara-C. Pts with bulky mediastinal disease were considered for local radiation therapy prior to starting POMP maintenance. Results: Between August 16, 2007 and March 6, 2019, we enrolled 96 pts with T-ALL (n=57) and T-LBL (n=39). Median age was 35 yrs (range 18-78), 75 pts were male (78%) and 83 pts (86%) had PS 0-1. In pts with T-ALL, median bone marrow blast % was 79% (range 0-96), 70 pts (73%) had extramedullary disease with mediastinal involvement in 48 pts and CNS involvement in 5 pts. 60 pts (63%) had diploid cytogenetics, 13 pts (14%) had complex cytogenetics, 19 pts had miscellaneous abnormalities and 4 pts had insufficient metaphases. Based on immunophenotype, pts were further characterized as thymic (n=38), early T-cell precursor (ETP; n=38), mature (n=10), not otherwise specified (NOS; n=9), and early-non-ETP (n=3). 12 pts had received prior therapy with HCVAD (n=8), asparaginase-based regimen (n=2), and others (n=2). 30-day mortality was 0%. 9 pts were in CR at enrollment. There were 242 grade 3/4 non-hematological treatment-emergent adverse events (TEAE) with the most frequent grade 3/4 TEAEs being neutropenic infections in 74 pts (77%), hypokalemia in 42 pts (44%), hypophosphatemia in 42 pts (44%) and elevated ALT in 28 pts (29%). Overall response rate was 98% (85/87 pts) with CR in 95% pts (n=83), PR in 2% (n=2), and no response in 2% (n=2). The median no. of cycles to response was 1 (range 1-10) with CR reported based on achieving PET negativity as well as standard response criteria. CR rate in T-ALL was 88% (43/49) and T-LBL was 100% (38/38). At a median follow-up of 58.8 months (mo; 95% CI 42.2, 67.6), 61 pts (63%) are alive with a median PFS and OS of 135.3 and 135.1 mo, respectively (Fig 1a, b) and 55 pts (57%) remain in CR. For pts who received NEL after HCVAD cycle 4, the 7-year OS was 61% compared to 52% who received NEL after cycle 8, hazard ratio 0.91, 95% CI 0.46, 1.82, p=0.7. For pts receiving PEG in addition to NEL, the 2yr OS was 86% (Fig 1c). 30 pts (31%) relapsed and 35 pts (37%) have died including 9 pts who died in CR. 17 pts (18%) pts underwent allogeneic stem cell transplantation, 6 have relapsed, 10 are alive, and 1 pt died in remission. Rate of relapse was 37% with NEL after cycle 8, 33% (16/49) with NEL after cycle 4 and 21% (3/14) with NEL/PEG (p=.38). Conclusion: HCVAD with NEL with or without PEG is safe and effective as frontline therapy of adults with newly diagnosed T-ALL/LBL. Addition of PEG appears to confer a benefit. Figure Disclosures Maiti: Celgene: Research Funding. Jabbour:Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. Jain:Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; ADC Therapeutics: Research Funding; Pfizer: Research Funding; BMS: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Borthakur:FTC Therapeutics: Consultancy; Curio Science LLC: Consultancy; Oncoceutics: Research Funding; Xbiotech USA: Research Funding; Cyclacel: Research Funding; PTC Therapeutics: Consultancy; BioLine Rx: Research Funding; BMS: Research Funding; AstraZeneca: Research Funding; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; BioLine Rx: Consultancy; Novartis: Research Funding; Abbvie: Research Funding; Jannsen: Research Funding; GSK: Research Funding; PTC Therapeutics: Research Funding; Polaris: Research Funding; BioTherix: Consultancy; Argenx: Consultancy; Incyte: Research Funding. Kadia:Incyte: Research Funding; Abbvie: Honoraria, Research Funding; Astellas: Research Funding; Astra Zeneca: Research Funding; Cyclacel: Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Research Funding; Celgene: Research Funding; Genentech: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Ascentage: Research Funding; Cellenkos: Research Funding; Novartis: Honoraria; Pulmotec: Research Funding. Burger:TG Therapeutics: Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Beigene: Research Funding, Speakers Bureau; Pharmacyclics, an AbbVie company: Consultancy, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy, Speakers Bureau. Konopleva:Kisoji: Consultancy; Agios: Research Funding; Genentech: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Amgen: Consultancy; Calithera: Research Funding; Cellectis: Research Funding; Ablynx: Research Funding; AbbVie: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding; Rafael Pharmaceutical: Research Funding; Forty-Seven: Consultancy, Research Funding; Eli Lilly: Research Funding; Sanofi: Research Funding. Alvarado:Jazz Pharmaceuticals: Research Funding; MEI Pharma: Research Funding; BerGenBio ASA: Research Funding; Sun Pharma: Research Funding; Daiichi-Sankyo: Research Funding; Tolero Pharmaceuticals: Research Funding; Astex Pharmaceuticals: Research Funding; FibroGen: Research Funding. Short:AstraZeneca: Consultancy; Amgen: Honoraria; Takeda Oncology: Consultancy, Honoraria, Research Funding; Astellas: Research Funding. Faderl:Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. O'Brien:Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc. Vaniam Group, AbbVie, Alexion, Verastem, Eisai, Juno Therapeutics, Vida Ventures: Consultancy; Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Consultancy, Research Funding; Kite, Regeneron, Acerta: Research Funding. Daver:Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding. Pemmaraju:Plexxikon: Research Funding; Affymetrix: Other: Grant Support, Research Funding; Pacylex Pharmaceuticals: Consultancy; Celgene: Honoraria; Daiichi Sankyo: Research Funding; DAVA Oncology: Honoraria; Samus Therapeutics: Research Funding; Cellectis: Research Funding; LFB Biotechnologies: Honoraria; Novartis: Honoraria, Research Funding; SagerStrong Foundation: Other: Grant Support; Incyte Corporation: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; Blueprint Medicines: Honoraria; Roche Diagnostics: Honoraria; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria. Bose:Astellas Pharmaceuticals: Research Funding; CTI BioPharma: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Kartos Therapeutics: Honoraria, Research Funding; Constellation Pharmaceuticals: Research Funding; Blueprint Medicines Corporation: Honoraria, Research Funding; Pfizer, Inc.: Research Funding; Incyte Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau; Promedior, Inc.: Research Funding; NS Pharma: Research Funding. Thompson:AbbVie: Research Funding; Pharmacyclics: Research Funding; Janssen-Cilag: Honoraria; Adaptive Biotechnologies: Consultancy, Research Funding; Genentech: Consultancy. Garcia-Manero:Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amphivena Therapeutics: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; AbbVie: Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Novartis: Research Funding; H3 Biomedicine: Research Funding; Onconova: Research Funding. Kantarjian:Amgen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Ascentage: Research Funding; Immunogen: Research Funding; Aptitute Health: Honoraria; BioAscend: Honoraria; Delta Fly: Honoraria; Janssen: Honoraria; Oxford Biomedical: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sanofi: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive biotechnologies: Honoraria; BMS: Research Funding; Jazz: Research Funding. Ravandi:Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria.

Background: Measurable residual disease (MRD) by multiparameter flow cytometry (MFC) is highly prognostic for relapse and overall survival (OS) in patients (pts) with acute lymphoblastic leukemia (ALL). However, many pts with apparent "MRD negativity" by MFC still relapse. These relapses are likely due to residual leukemia that is present below the level of detection of MFC (generally ~1x10-4). In light of the limitations of conventional MRD assays, we sought to evaluate the clinical impact of a highly sensitive next-generation sequencing (NGS)-based MRD assay that is capable of detecting residual leukemia at a level of 1x10-6. Methods: We performed a retrospective study of 67 pts with previously untreated Philadelphia chromosome-negative ALL who received frontline therapy between 2/2012 and 7/2018 with a hyper-CVAD-based regimen (n=44) or a lower-intensity hyper-CVD-based regimen (n=23), which was usually combined with inotuzumab ozogamicin, and achieved complete remission (CR). Pts were selected for this study based on availability of banked samples at baseline and at sequential remission time points up to 4.5 months after start of therapy. Six-color MFC was performed as standard of care with an analytic sensitivity of 0.01% (1x10-4). Pretreatment genomic DNA derived from bone marrow was evaluated using a quantitative NGS MRD assay (Adaptive Biotechnologies Co., Seattle, WA) to identify dominant rearrangements within the B-cell receptor (IgH [VDJ and DJ], IgK and IgL). High throughput NGS of remission samples was subsequently performed to assess the target clonal rearrangements at an established analytic sensitivity of 0.0001% (1x10-6). Results: The baseline characteristics of the study population are shown in Table 1. Twenty pts (30%) underwent allogeneic stem cell transplant (alloSCT) in first remission. In the entire cohort, 14 pts relapsed (21%), including 2 with CNS-only relapses. The median duration of follow-up for the entire cohort was 51 months. Among the 109 remission samples, 84 were MRD-negative (MRDneg), 24 were MRD-positive (MRDpos), and 1 was indeterminate by MFC (Figure 1). All 24 MRDpos samples by MFC were also MRDpos by NGS. Among the 84 MRDneg samples by MFC, 32 (38%) were MRDpos by NGS. For these discordant cases, the median level of MRD by NGS was below the expected level of detection by MFC (median 0.002% [range 0.00002%-1.15%]). At the time of CR, 44/67 pts (66%), achieved MRDneg by MFC and 14/38 (37%) achieved MRDneg by NGS. The rates of MRDneg by MFC in pts treated with hyper-CVAD or hyper-CVD regimens were 61% and 74%, respectively, and by NGS were 32% and 46%, respectively. Achieving MRDneg by NGS at the time of CR better predicted the likelihood of durable remission than did achieving MRDneg by MFC. The 5-year cumulative incidence of relapse (CIR) of the 44 pts who achieved MRDneg by MFC and of 14 pts who achieved MRDneg by NGS was 27% and 8%, respectively. Only 1 out of 14 pts who achieved MRDneg by NGS at the time of CR subsequently relapsed. In contrast, MRD status by NGS did not predict for relapse when evaluated at post-CR time points. Among pts treated with a more intensive hyper-CVAD regimen, achievement of MRDneg by NGS at CR provided additional prognostic information compared to MRD status by MFC at the same time point and identified pts with an excellent long-term outcome. The 5-year OS rate for pts who achieved MRDneg by NGS at CR was 100% vs. 55% for those who were MRDpos by NGS (Figure 2A; P Conclusion: Early assessment of MRD using an ultrasensitive NGS assay can identify pts with ALL who have a very low risk of relapse and excellent long-term survival. Prospective studies are warranted to assess whether de-intensification of therapy is feasible for this favorable-risk group of pts who rapidly achieve MRDneg remission. Disclosures Short: Amgen: Honoraria; Astellas: Research Funding; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Honoraria, Research Funding. Kantarjian:Takeda: Honoraria; Amgen: Honoraria, Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cyclacel: Research Funding; Pfizer: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Novartis: Research Funding; Immunogen: Research Funding; AbbVie: Honoraria, Research Funding; BMS: Research Funding; Ariad: Research Funding; Jazz Pharma: Research Funding; Daiichi-Sankyo: Research Funding; Astex: Research Funding. Konopleva:F. Hoffmann La-Roche: Consultancy, Research Funding; Eli Lilly: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; Rafael Pharmaceutical: Research Funding; Amgen: Consultancy; Sanofi: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Ablynx: Research Funding; Agios: Research Funding; AbbVie: Consultancy, Research Funding; Ascentage: Research Funding; AstraZeneca: Research Funding; Forty-Seven: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Kisoji: Consultancy; Genentech: Consultancy, Research Funding. Jain:Cellectis: Research Funding; BMS: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aprea Therapeutics: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kebriaei:Kite: Other: Served on advisory board; Amgen: Other: Research Support; Ziopharm: Other: Research Support; Pfizer: Other: Served on advisory board; Novartis: Other: Served on advisory board; Jazz: Consultancy. Yilmaz:Pfizer: Research Funding; Daicho Sankyo: Research Funding; Pint Pharma: Honoraria. Issa:Celegene: Research Funding; Syndax: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Ravandi:BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding. Jabbour:Amgen: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding.

Background Addition of the BCL2 inhibitor venetoclax to lower intensity therapy improved survival (OS) for older and unfit patients with newly diagnosed AML. We have previously reported the safety and efficacy of the nucleoside analogue cladribine combined with high dose ara-C and idarubicin (ida) as an intensive induction regimen (CLIA) in patients with newly diagnosed AML. Here, we report the results of the combination of venetoclax with the CLIA regimen for younger, fit patients with newly diagnosed AML. Methods Patients < 65 years of age with newly diagnosed AML or high-risk MDS were enrolled (NCT02115295). Induction was cladribine 5 mg/m2 IV on D1-5, ara-C 1.5 g/m2 IV on D1-5, and idarubicin 10 mg/m2 IV on D1-3; venetoclax was given at an effective dose of 400mg PO on D2-8 without ramp up with every cycle. Consolidation consisted of 3d of CLIA (2d of ida). AML patients with FLT3-ITD or FLT3 point mutations could receive midostaurin on D6-19 or gilteritinib on D1-14 for induction, and continuously thereafter. Venetoclax dose modifications for CYP3A4 inhibitors were made. All patients underwent baseline next generation sequencing and MRD testing by multiparameter flow cytometry at the time of response. Results A total of 31 patients have been enrolled. The median age was 48 years (range, 18-64). Baseline characteristics are shown in Table 1. Median follow up is 8.8 months. All patients were evaluable for response, with 28 of 31 (90%) achieving a remission, including 23 (74%) complete remission (CR) and 5 (16%) CR with incomplete count recovery (CRi) (Table 1). Of the 2 patients that did not respond, one was ELN adverse risk with TP53 mutation and complex karyotype, the other was ELN favorable risk with a t(8;21) translocation and mutations in IDH1 and JAK2. At time of initial response assessment 19 of 30 (63%) had undetectable MRD, with another 4 patients (77%) becoming MRD negative overall. Median cycles until response was 1 (range: 1 - 2), and patients have received a median of 2 cycles (range: 1 - 5). Median time to absolute neutrophil count ≥ 1000/µL was 32 days (range: 18 - 49) and platelet count ≥ 50k and 100k/µL were 29 days (range: 17 - 61) and 32 days, respectively after induction. 8 patients received FLT3 inhibition (FLT3i) in addition to CLIA and venetoclax, 7 (88%) with gilteritinib and 1 (12%) with midostaurin. Within this subset, there were 6/8 (75%) CR and 1 CR (12%) (Table 2). Median overall survival (OS) for those receiving FLT3i is not yet reached (95% CI: 0.79 - NE months). Median duration of response for the entire cohort is not reached. At 6 and 12 months 87% of responders had an ongoing response (SE=9%). 18 of 28 (64%) of responders received an allogeneic stem cell transplant. Median OS has not been reached, with 6- and 12-month rates of OS 93% (SE=5%) and 81% (SE=9%), respectively (Figure 1). Median OS in all ELN risk categories has not yet been reached, with 6 month OS of 91% (SE=9%), 100% (SE=NA), and 83% (SE=15%) in favorable, intermediate, and adverse risk groups, respectively (Figure 2). Median event free survival (EFS) has not been reached, with 6- and 12-month rates of EFS are 90% (SE=5%) and 79% (SE=9%), respectively. Overall the regimen was well tolerated, with an acceptable toxicity profile. Tumor lysis syndrome was not seen. The most common Grade >/= 3 adverse events were neutropenic fever, pneumonia, nausea, and liver transaminitis. There was one induction death in the FLT3i cohort and none with CLIA + venetoclax. Conclusion Venetoclax added to CLIA was safe and highly effective in newly diagnosed pts with AML and high risk MDS, including patients with FLT3-mutated AML and adverse risk by ELN or IPSS-R. The addition of FLT3i may be associated with delayed count recovery. CLIA plus venetoclax provided high rates of durable MRD negative remissions and encouraging event-free and overall survival across prognostic subgroups. Disclosures Kantarjian: BMS: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive biotechnologies: Honoraria; Aptitute Health: Honoraria; BioAscend: Honoraria; Daiichi-Sankyo: Honoraria, Research Funding; Immunogen: Research Funding; Jazz: Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Sanofi: Research Funding; Delta Fly: Honoraria; Ascentage: Research Funding; Janssen: Honoraria; Abbvie: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Oxford Biomedical: Honoraria. Borthakur:Abbvie: Research Funding; BioLine Rx: Consultancy; FTC Therapeutics: Consultancy; BioTherix: Consultancy; Jannsen: Research Funding; GSK: Research Funding; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; Argenx: Consultancy; AstraZeneca: Research Funding; Cyclacel: Research Funding; PTC Therapeutics: Consultancy; PTC Therapeutics: Research Funding; Novartis: Research Funding; BioLine Rx: Research Funding; BMS: Research Funding; Incyte: Research Funding; Curio Science LLC: Consultancy; Oncoceutics: Research Funding; Xbiotech USA: Research Funding; Polaris: Research Funding. Yilmaz:Daicho Sankyo: Research Funding; Pint Pharma: Honoraria; Pfizer: Research Funding. DiNardo:ImmuneOnc: Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; Jazz: Honoraria; MedImmune: Honoraria; Syros: Honoraria; Novartis: Consultancy. Andreeff:Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy. Daver:Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Jain:Aprea Therapeutics: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Pfizer: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Cellectis: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Jabbour:Takeda: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding. Short:Astellas: Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Honoraria, Research Funding. Alvarado:Daiichi-Sankyo: Research Funding; BerGenBio ASA: Research Funding; Tolero Pharmaceuticals: Research Funding; Astex Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Research Funding; FibroGen: Research Funding; MEI Pharma: Research Funding; Sun Pharma: Research Funding. Bose:Constellation Pharmaceuticals: Research Funding; Celgene Corporation: Honoraria, Research Funding; CTI BioPharma: Honoraria, Research Funding; Blueprint Medicines Corporation: Honoraria, Research Funding; Pfizer, Inc.: Research Funding; Astellas Pharmaceuticals: Research Funding; NS Pharma: Research Funding; Promedior, Inc.: Research Funding; Incyte Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau; Kartos Therapeutics: Honoraria, Research Funding. Garcia-Manero:Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; AbbVie: Honoraria, Research Funding; H3 Biomedicine: Research Funding; Amphivena Therapeutics: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Onconova: Research Funding; Novartis: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy, Honoraria, Research Funding. Konopleva:Sanofi: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Ablynx: Research Funding; Genentech: Consultancy, Research Funding; Ascentage: Research Funding; Amgen: Consultancy; Agios: Research Funding; AstraZeneca: Research Funding; Eli Lilly: Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Rafael Pharmaceutical: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; Kisoji: Consultancy; AbbVie: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Forty-Seven: Consultancy, Research Funding. Ravandi:Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; AstraZeneca: Consultancy, Honoraria; Xencor: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding. Kadia:Amgen: Research Funding; Cellenkos: Research Funding; Cyclacel: Research Funding; Genentech: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Novartis: Honoraria; BMS: Honoraria, Research Funding; Astra Zeneca: Research Funding; Celgene: Research Funding; Ascentage: Research Funding; Astellas: Research Funding; Pulmotec: Research Funding; Incyte: Research Funding; Pfizer: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding.

Background: For patients (pts) with Philadelphia chromosome (Ph)-negative B-cell acute lymphoblastic leukemia (ALL), combination chemotherapy achieves complete remission rates of 80-90%; however, many pts ultimately relapse, leading to a cure rate of only 40-50%. Blinatumomab is highly effective in both the relapsed/refractory setting and for eradication of measurable residual disease (MRD). We hypothesized that early incorporation of blinatumomab in pts with newly diagnosed Ph-negative B-cell ALL would decrease the need for intensive chemotherapy, lead to deeper and more durable responses, and improve survival. Methods: Pts 14-59 years of age with newly diagnosed Ph-negative pre-B-cell ALL, including pts who had received no more than 1 prior cycle of chemotherapy, were eligible. Pts were required to have a performance status of ≤3, total bilirubin ≤2 mg/dl and creatinine ≤2 mg/dl. Pts received hyper-CVAD alternating with high-dose methotrexate and cytarabine for up to 4 cycles, followed by 4 cycles of blinatumomab at standard doses. Pts with CD20+ disease (≥1% cells) received 8 doses of ofatumumab (2000 mg) or rituximab (375 mg/m2). Eight administrations of prophylactic IT chemotherapy were given in the first 4 cycles. Maintenance was with alternating blocks of POMP (given in maintenance cycles 1-3, 5-7, 9-11, and 13-15) and blinatumomab (given in maintenance cycles 4, 8, and 12). After 2 pts with high-risk features experienced early relapse prior to blinatumomab administration, for pts #10+ the protocol was amended so that pts with high-risk disease features (e.g. CRLF2+ by flow cytometry, complex karyotype, KMT2A rearranged, low-hypodiploidy/near triploidy, TP53 mutation, or persistent MRD) started blinatumomab after 2 cycles of hyper-CVAD. Results: 39 pts have been treated, 34 of whom are evaluable for efficacy (5 too early for assessment). 6 pts were in complete remission (CR) at enrollment and unevaluable for morphologic response. Pt characteristics of the 34 evaluable pts are summarized in Table 1. Median age was 36 years (range, 17-59 years). At least one high-risk feature was present in 19 pts (56%), including TP53 mutation in 27%, CRLF2+ in 20%, and an adverse-risk karyotype in 26%. 82% of pts received ofatumumab or rituximab. Among 28 pts with active disease at study entry, 100% achieved CR, with 82% achieving CR after the first cycle. MRD negativity by 6-color flow cytometry was achieved in 20/23 responding pts (87%) after 1 cycle and 33/34 pts (97%) overall. There were no early deaths, and the 60-day mortality rate was 0%. With a median follow-up of 22 months (range, 1-40 months), the 2-year continuous remission and OS rates were 79% and 86%, respectively (Figure 1). Overall, 5 pts (15%) relapsed, 12 (35%) underwent allogeneic SCT in first remission (including 1 additional pt who relapsed post-SCT), and 17 (50%) remain in continuous remission and are currently on treatment or have completed maintenance. All relapses occurred in pts with established poor-risk features, including 2 pts with KMT2A rearrangement, 2 pts with TP53 mutation (1 of whom was low hypodiploid), and 1 pt with baseline WBC count of 32 x 109/L. Two of these relapses occurred during hyper-CVAD cycles before the amendment allowing for earlier integration of blinatumomab for pts with high-risk disease features. Treatment was overall well-tolerated. Four pts developed grade 2-3 cytokine release syndrome (grade 2, n=3; grade 3, n=1) which resolved with corticosteroids and interruption of blinatumomab. Overall, 14 (41%) pts had a neurological AE of any grade due to blinatumomab. Only one pt discontinued blinatumomab due to blinatumomab-related adverse event (grade 2 encephalopathy and dysphasia). Conclusion: Sequential combination of hyper-CVAD and blinatumomab is highly effective as frontline treatment of Ph-negative B-cell ALL, with a CR rate of 100% and 97% of pts achieving MRD negativity. Survival data are promising with an estimated 2-year OS of 86%, which compares favorably to historical controls. This study continues to accrue pts. Disclosures Short: Astellas: Research Funding; Amgen: Honoraria; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Honoraria, Research Funding. Kantarjian:Jazz: Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Oxford Biomedical: Honoraria; Aptitute Health: Honoraria; BioAscend: Honoraria; Delta Fly: Honoraria; Janssen: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immunogen: Research Funding; BMS: Research Funding; Adaptive biotechnologies: Honoraria; Abbvie: Honoraria, Research Funding; Sanofi: Research Funding; Amgen: Honoraria, Research Funding; Ascentage: Research Funding. Ravandi:Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; AstraZeneca: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding. Kadia:Abbvie: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Cyclacel: Research Funding; Astellas: Research Funding; Cellenkos: Research Funding; Pfizer: Honoraria, Research Funding; Celgene: Research Funding; Pulmotec: Research Funding; Amgen: Research Funding; Genentech: Honoraria, Research Funding; Ascentage: Research Funding; Incyte: Research Funding; JAZZ: Honoraria, Research Funding; Novartis: Honoraria; Astra Zeneca: Research Funding. Thompson:Pharmacyclics: Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; Genentech: Consultancy; Janssen-Cilag: Honoraria; AbbVie: Research Funding. Alvarado:Tolero Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; Astex Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Research Funding; Sun Pharma: Research Funding; BerGenBio ASA: Research Funding; MEI Pharma: Research Funding; FibroGen: Research Funding. Jain:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Pfizer: Research Funding; ADC Therapeutics: Research Funding; Incyte: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aprea Therapeutics: Research Funding. Yilmaz:Pint Pharma: Honoraria; Pfizer: Research Funding; Daicho Sankyo: Research Funding. Konopleva:Calithera: Research Funding; Genentech: Consultancy, Research Funding; Amgen: Consultancy; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Agios: Research Funding; AstraZeneca: Research Funding; Cellectis: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Forty-Seven: Consultancy, Research Funding; Rafael Pharmaceutical: Research Funding; Eli Lilly: Research Funding; AbbVie: Consultancy, Research Funding; Ascentage: Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Kisoji: Consultancy; Sanofi: Research Funding; Ablynx: Research Funding. Garcia-Manero:AbbVie: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Amphivena Therapeutics: Research Funding; Jazz Pharmaceuticals: Consultancy; Merck: Research Funding; H3 Biomedicine: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding. O'Brien:Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc. Vaniam Group, AbbVie, Alexion, Verastem, Eisai, Juno Therapeutics, Vida Ventures: Consultancy; Kite, Regeneron, Acerta: Research Funding; Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Consultancy, Research Funding. Jabbour:Takeda: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding. OffLabel Disclosure: Blinatumomab - frontline therapy for ALL

Background: Inotuzumab ozogamicin (INO) and blinatumomab both improve overall survival (OS) in relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). Use of these effective monoclonal antibodies in the frontline setting may lead to deep and durable remissions in older adults with newly diagnosed Philadelphia chromosome (Ph)-negative B-cell ALL. Methods: Patients (pts) ≥60 years of age with newly diagnosed Ph-negative pre-B-cell ALL, including pts who had received no more than 1 prior cycle of chemotherapy, were eligible. Pts were required to have a performance status of ≤3, total bilirubin ≤1.5 mg/dl, AST/ALT ≤3x ULN and creatinine ≤2 mg/dl. Pts received mini-hyper-CVD (cyclophosphamide and dexamethasone at 50% dose reduction, no anthracycline, methotrexate at 75% dose reduction, cytarabine at 0.5 g/m2 x 4 doses) for up to 8 cycles. INO was initially given at a dose of 1.3-1.8mg/m2 on day 3 of cycle 1 and 0.8-1.3mg/m2 on day 3 of cycles 2-4. Rituximab (if CD20+) and prophylactic IT chemotherapy were given for the first 4 cycles. Responding pts received POMP maintenance for up to 3 years. In order to decrease the risk of veno-occlusive disease (VOD), the protocol was amended in 3/2017 (pts 50+) to give INO in fractionated doses each cycle (0.6 mg/m2 on day 2 and 0.3 mg/m2 on day 8 of cycle 1; 0.3 mg/m2 on day 2 and 8 of cycles 2-4) and to administer 4 cycles of blinatumomab following 4 cycles of hyper-CVD plus INO, followed by maintenance with 12 cycles of POMP and 4 cycles of blinatumomab (1 cycle of blinatumomab after every 3 cycles of POMP). The cumulative dose of INO given before and after this most recent amendment was 4.3 mg/m2 and 2.7 mg/m2, respectively. Results: 73 pts have been treated, 70 of whom are evaluable for efficacy (3 pts too early for response assessment). 6 pts were in complete remission (CR) at enrollment and unevaluable for morphological response. Pt characteristics of the 70 evaluable pts are summarized in Table 1. Median age was 68 years (range, 60-81 years); 29 pts (41%) were ≥70 years. 41% were positive for TP53 mutation, 18% were CRLF2 positive by flow cytometry, and 27% had adverse-risk karyotype. 38/64 pts (59%) were CD20+ and received rituximab. Among 64 pts evaluable for morphologic response, 63 (98%) responded (CR, n=56; CRp, n=6; CRi, n=1). MRD negativity by flow cytometry was achieved in 53/66 pts (80%) after 1 cycle and 65/68 pts (96%) overall. There were no early deaths, and the 30-day and 60-day mortality rates were 0% and 3%, respectively. Among 69 pts who achieved remission, 9 (13%) relapsed, 3 (4%) underwent allogeneic SCT in first remission (1 of whom subsequently relapsed), 35 (51%) remain on treatment or have completed therapy, and 21 (32%) died in CR/CRp. Notably, 6 pts (9%) developed VOD, 1 after subsequent allogeneic SCT. The rate of VOD was 6/70 (9%) with no difference in rate of VOD in pts who did or did not receive fractionated INO and blinatumomab. With a median follow-up of 45 months (range, 2-98 months), the 4-year continuous remission and OS rates were 78% and 50%, respectively (Figure 1A). Age and cytogenetic risk were the primary factors associated with OS. The 4-year OS rate was 61% in pts 60-69 years vs. 34% in pts ≥70 years (P=0.06), driven by higher rates of death in remission in the older pts (13/29 [45%] vs. 8/41 [20%] in pts 60-69 years of age; P=0.03). These remission deaths in pts ≥70 years were primarily due to infection (n=7) or development of MDS/AML (n=3). Pts with high-risk cytogenetic features (e.g. KMT2A rearranged, low hypodiploidy/near triploidy, complex cytogenetics) had a 4-year OS rate of 22% vs. 57% for patients without high-risk cytogenetic features (Figure 1B; P=0.009). Neither CRLF2 positivity by flow cytometry nor the presence of a TP53 mutation significantly impacted OS. Conclusion: Reduced-intensity chemotherapy with hyper-CVD plus INO, with or without blinatumomab, is safe and effective in older adults with newly diagnosed Ph-negative ALL, with an overall response rate of 98% and 4-year OS rate of 50%. This novel regimen leads to durable remissions and apparent cure in the majority of pts age 60-69 years of age and in those without poor-risk cytogenetic features. To decrease treatment-related mortality, the protocol has been amended to eliminate chemotherapy for pts ≥70 years of age. Disclosures Short: Amgen: Honoraria; Takeda Oncology: Consultancy, Honoraria, Research Funding; Astellas: Research Funding; AstraZeneca: Consultancy. Kantarjian:Janssen: Honoraria; Abbvie: Honoraria, Research Funding; Immunogen: Research Funding; Oxford Biomedical: Honoraria; Delta Fly: Honoraria; Adaptive biotechnologies: Honoraria; Aptitute Health: Honoraria; Daiichi-Sankyo: Honoraria, Research Funding; BioAscend: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ascentage: Research Funding; Amgen: Honoraria, Research Funding; Jazz: Research Funding; Sanofi: Research Funding; Pfizer: Honoraria, Research Funding; BMS: Research Funding; Novartis: Honoraria, Research Funding. Ravandi:Celgene: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding. Jain:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Research Funding; Aprea Therapeutics: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; BMS: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; Incyte: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Kadia:JAZZ: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Novartis: Honoraria; Astra Zeneca: Research Funding; Cyclacel: Research Funding; Ascentage: Research Funding; Genentech: Honoraria, Research Funding; Amgen: Research Funding; Cellenkos: Research Funding; Celgene: Research Funding; Astellas: Research Funding; Incyte: Research Funding; Pulmotec: Research Funding. Alvarado:FibroGen: Research Funding; Astex Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; Sun Pharma: Research Funding; MEI Pharma: Research Funding; Tolero Pharmaceuticals: Research Funding; BerGenBio ASA: Research Funding; Jazz Pharmaceuticals: Research Funding. Burger:Janssen Pharmaceuticals: Consultancy, Speakers Bureau; TG Therapeutics: Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Pharmacyclics, an AbbVie company: Consultancy, Research Funding, Speakers Bureau; Beigene: Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Research Funding. Daver:Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees. Borthakur:Abbvie: Research Funding; Jannsen: Research Funding; Xbiotech USA: Research Funding; Polaris: Research Funding; BMS: Research Funding; Oncoceutics: Research Funding; Curio Science LLC: Consultancy; AstraZeneca: Research Funding; Novartis: Research Funding; Incyte: Research Funding; PTC Therapeutics: Consultancy; Argenx: Consultancy; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; PTC Therapeutics: Research Funding; GSK: Research Funding; FTC Therapeutics: Consultancy; Cyclacel: Research Funding; BioLine Rx: Consultancy; BioLine Rx: Research Funding. DiNardo:Novartis: Consultancy; ImmuneOnc: Honoraria; Syros: Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; MedImmune: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Jazz: Honoraria. Konopleva:Forty-Seven: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Cellectis: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; AstraZeneca: Research Funding; Amgen: Consultancy; Ablynx: Research Funding; Agios: Research Funding; Ascentage: Research Funding; Eli Lilly: Research Funding; Calithera: Research Funding; Sanofi: Research Funding; Genentech: Consultancy, Research Funding; Kisoji: Consultancy; Rafael Pharmaceutical: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; F. Hoffmann La-Roche: Consultancy, Research Funding. Pemmaraju:Plexxikon: Research Funding; Cellectis: Research Funding; Daiichi Sankyo: Research Funding; Samus Therapeutics: Research Funding; Incyte Corporation: Honoraria; Pacylex Pharmaceuticals: Consultancy; Celgene: Honoraria; AbbVie: Honoraria, Research Funding; Blueprint Medicines: Honoraria; Affymetrix: Other: Grant Support, Research Funding; SagerStrong Foundation: Other: Grant Support; Stemline Therapeutics: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; DAVA Oncology: Honoraria; Novartis: Honoraria, Research Funding; Roche Diagnostics: Honoraria; MustangBio: Honoraria. Garcia-Manero:Jazz Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amphivena Therapeutics: Research Funding; Merck: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; H3 Biomedicine: Research Funding; Onconova: Research Funding. O'Brien:Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Consultancy, Research Funding; Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc. Vaniam Group, AbbVie, Alexion, Verastem, Eisai, Juno Therapeutics, Vida Ventures: Consultancy; Kite, Regeneron, Acerta: Research Funding. Jabbour:Amgen: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. OffLabel Disclosure: Inotuzumab ozogamicin and blinatumomab - frontline treatment of ALL

Background The success of allogenic stem cell transplantation in curing AML suggests that the immune system can be harnessed to eradicate AML. In a phase 2 trial (NCT02397720) in relapsed/refractory (R/R) AML patients, we demonstrated that the azacitidine/nivolumab combination improved response rates and median overall survival compared with similar patients treated on other azacitidine-based studies (Daver et al Cancer Discovery 2019). The heterogenous response profiles and shorter duration of responses than seen in solid tumor patients suggested hitherto undefined tumor intrinsic, tumor microenvironment (TME) and T cell factors may impede PD-1 blockade therapy in AML. Methods We performed single cell RNA sequencing (scRNAseq) of 13,633 healthy bone marrow (BM) donor, and 113,394 BM cells from 22 aspirates (8 pre- and 14 post- treatment) from 8 R/R AML patients (median age 73 years; range 64-88 years) treated with azacitidine/nivolumab (Fig 1A). 3/8 patients were responders (2CR, 1 PR), while 2/8 and 3/8 had stable disease (SD), and no response (NR), respectively, allowing us to evaluate factors involved in response, relapse and resistance to azacitidine/nivolumab. Results A total of 60,753 AML and 52,641 TME cells passed scRNAseq quality check, with the proportion of identified AML cells correlating with clinical flow cytometry (r=0.87, p=1.5x10-7) and immunohistochemistry (r=0.73, p=0.0001). Pre- and post-treatment AML cells clustered by patient and had distinct cell cycle profiles regardless of response type, suggesting significant inter-tumor heterogeneity (Fig 1B). In an aggregate analysis of all cells at the pretreatment timepoint, the 3 responders had lower leukemia stemness (LSC17) scores compared with NR (p On paired single cell TCR analysis from 4,742 and 26,095 T cells from healthy and R/R AML BMs, respectively, T cells in the TME of AML patients had less clonal diversity and more oligoclonal dominance compared to healthy BMs (Fig 1G-H). Following treatment 76.9% and 72.4% of novel and expanded clones were contributed by responders, with non-responders contributing only 5% and 3.4% of the novel and expanded clones, respectively (Fig. 1I). Among responders, the majority of clones were either novel or expanded, whereas NR had mostly contracted clones. Conclusions: This is one of the first studies examining the effect of PD-1 blockade at single cell resolution in a hematologic malignancy. Further, this is the largest single study analyzing single AML cells longitudinally. AML cells harboring deletion 7/7q loss, enriched for LSC signature and metabolic/oxidative pathways, were features associated with resistance to azacitidine/nivolumab therapy. Azacitidine/nivolumab induced novel and expanded T cell clonotypes primarily in responders. Disentangling AML cells from their complex microenvironment revealed characteristics that shaped resistance to ICB-based therapy and could inform strategies to target AML vulnerabilities. Disclosures DiNardo: Takeda: Honoraria; Novartis: Consultancy; AbbVie: Consultancy, Honoraria, Research Funding; Syros: Honoraria; MedImmune: Honoraria; Jazz: Honoraria; Agios: Consultancy, Honoraria, Research Funding; ImmuneOnc: Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees. Kadia:Pfizer: Honoraria, Research Funding; Cyclacel: Research Funding; Incyte: Research Funding; Novartis: Honoraria; Abbvie: Honoraria, Research Funding; Astellas: Research Funding; Cellenkos: Research Funding; Ascentage: Research Funding; Amgen: Research Funding; JAZZ: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Astra Zeneca: Research Funding; Celgene: Research Funding; Genentech: Honoraria, Research Funding; Pulmotec: Research Funding. Ravandi:Celgene: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Astellas: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding. Borthakur:Xbiotech USA: Research Funding; BioLine Rx: Research Funding; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; Incyte: Research Funding; Novartis: Research Funding; Jannsen: Research Funding; Abbvie: Research Funding; Cyclacel: Research Funding; Argenx: Consultancy; FTC Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; PTC Therapeutics: Research Funding; Polaris: Research Funding; BMS: Research Funding; Oncoceutics: Research Funding; Nkarta Therapeutics: Consultancy; BioTherix: Consultancy; GSK: Research Funding; Curio Science LLC: Consultancy; AstraZeneca: Research Funding. Konopleva:Ascentage: Research Funding; Eli Lilly: Research Funding; Rafael Pharmaceutical: Research Funding; Forty-Seven: Consultancy, Research Funding; Ablynx: Research Funding; Amgen: Consultancy; F. Hoffmann La-Roche: Consultancy, Research Funding; AstraZeneca: Research Funding; AbbVie: Consultancy, Research Funding; Calithera: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Kisoji: Consultancy; Cellectis: Research Funding; Sanofi: Research Funding; Genentech: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Agios: Research Funding. Garcia-Manero:Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Jazz Pharmaceuticals: Consultancy; Acceleron Pharmaceuticals: Consultancy, Honoraria; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Amphivena Therapeutics: Research Funding; Novartis: Research Funding; AbbVie: Honoraria, Research Funding; H3 Biomedicine: Research Funding; Onconova: Research Funding. Green:KDAc Therapeutics: Current equity holder in private company. Sharma:Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Constellation: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAb: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Oncolytics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Infinity Pharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Glympse: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Allison:Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAB: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Daver:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; ImmunoGen: Research Funding; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Background: Blockade of PD-1/PD-L1 pathways enhances anti-leukemic responses in pre-clinical studies. PD1 inhibition alone had limited clinical activity in AML. CLTA4 inhibition demonstrated encouraging single-agent CR's in postASCT patients (pts), especially for extra-medullary (EMD) relapses (Davis M et al, NEJM 2016). AZA+Nivo up-regulated CTLA4 on bone marrow (BM) CD8 cells in both responders (R) and non-responders (NR) on treatment (Daver N, et al, Cancer Discovery 2019), suggesting a triplet of AZA+Nivo+Ipi may abrogate PD-1 mediated resistance. Methods: Pts were eligible for the AZA+Nivo (cohort 1, n=59) if they had R/R AML, ECOG ≤ 2, and adequate organ function. This cohort has completed enrollment. A cohort of AZA+Nivo+Ipi was opened (cohort 2), with the same eligibility criteria. Ipi 1mg/kg Q6 weeks was added to the established AZA+Nivo schedule and found to be safe in a lead-in dose cohort. Results: Cohort 1 (59 R/R AML) pts were treated with Aza+Nivo (Daver et al., Cancer Discovery 2019). CR/CRi and OS were superior to contemporary historic HMA-based clinical trial controls at MDACC (Table 1). Pts with low pretherapy BM blasts ( Cohort 2 (36 R/R AML) pts were treated with Aza+Nivo+Ipi, with med age 67 years (25-83), secondary AML (50%), ELN unfavorable cytogenetics (67%), TP53 (36%), med salvage 2 (range, 1-3), and prior HMA based therapies in 67%. All 36 pts are evaluable. Per ELN 2017, CR/CRi was noted in 7 (19%) and PR in 1 (3%). Five (14%) pts had durable stable disease (SD) (defined as absence of CR, CRi, PR; with SD on treatment for ≥6 months), and 23 (64%) were NRs (Table 1). Interestingly, 4 pts with EMD were enrolled and 3 had CR/PR [med DOR 8 (5-13) mos]. The 4- and 8-week mortalities were 0 and 6%, respectively. Grade 3/4 immune toxicities noted in 8 pts (19%), including rash, pneumonitis, colitis, pyrexia. One pt required ICU stay, but no deaths attributed to immune toxicity. Other grade ≥2 toxicities were as expected for R/R AML population and were mostly infections/febrile neutropenia. Converse to AZA+Nivo, on CYTOF, R did not have a higher frequency of pre-therapy BM CD8+ infiltration, but did have progressive BM CD8+ infiltration on therapy, compared with NRs, demonstrating that Ipi (unlike Nivo) may be able to mobilize peripheral T-cells to the BM (Fig 1B). Expansion of a cluster of antigen experienced CD8+ T cells was associated with response (Fig 1B). In all salvage the med OS with Aza+Ipi+Nivo versus Aza+Nivo versus contemporary HMA-controls in R/R AML, were 7.6, 5.9, and 4.6 mos, respectively (P=0.01) (Fig 1C). The 1-year OS in R/R AML pts with AZA+Nivo+Ipi was 25%. The med OS with Aza+Ipi+Nivo was comparable to med OS 6-8 mos reported with HMA+VEN salvage in numerous studies. Conclusion: The OS with Aza+Nivo+Ipi was modestly improved over AZA+Nivo and HMA-controls in R/R AML. Single-cell cytokine profiling and single-cell RNA-seq from Aza+Nivo showed striking pre- and on-treatment differences among R and NR not only in T-cell fitness and clonality, but also in the tumor microenvironment. Ipi may be uniquely able to mobilize peripheral T-cell to BM and EMD. This underappreciated immune diversity suggests a critical need for biomarker-based trials (as we are doing with molecular therapies) for immunotherapies in AML. Disclosures Daver: Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Garcia-Manero:Merck: Research Funding; Onconova: Research Funding; Novartis: Research Funding; Jazz Pharmaceuticals: Consultancy; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; H3 Biomedicine: Research Funding; AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Amphivena Therapeutics: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Konopleva:Eli Lilly: Research Funding; Rafael Pharmaceutical: Research Funding; Genentech: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Agios: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Sanofi: Research Funding; Kisoji: Consultancy; Amgen: Consultancy; F. Hoffmann La-Roche: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Ablynx: Research Funding; Forty-Seven: Consultancy, Research Funding. Kadia:Pulmotec: Research Funding; Astellas: Research Funding; Cellenkos: Research Funding; Amgen: Research Funding; Genentech: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Cyclacel: Research Funding; JAZZ: Honoraria, Research Funding; Celgene: Research Funding; Incyte: Research Funding; Astra Zeneca: Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria; Abbvie: Honoraria, Research Funding. DiNardo:AbbVie: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Agios: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Jazz: Honoraria; MedImmune: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Syros: Honoraria; Notable Labs: Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria; Novartis: Consultancy. Borthakur:Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding; PTC Therapeutics: Research Funding; Curio Science LLC: Consultancy; FTC Therapeutics: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; Oncoceutics: Research Funding; Xbiotech USA: Research Funding; Polaris: Research Funding; AstraZeneca: Research Funding; BMS: Research Funding; BioLine Rx: Research Funding; Cyclacel: Research Funding; GSK: Research Funding; Jannsen: Research Funding. Pemmaraju:AbbVie: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Stemline Therapeutics: Honoraria, Research Funding; DAVA Oncology: Honoraria; Incyte Corporation: Honoraria; Celgene: Honoraria; Novartis: Honoraria, Research Funding; SagerStrong Foundation: Other: Grant Support; Plexxikon: Research Funding; LFB Biotechnologies: Honoraria; Blueprint Medicines: Honoraria; Samus Therapeutics: Research Funding; Affymetrix: Other: Grant Support, Research Funding; Pacylex Pharmaceuticals: Consultancy; MustangBio: Honoraria; Roche Diagnostics: Honoraria; Cellectis: Research Funding. Jabbour:Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding. Sasaki:Novartis: Consultancy, Research Funding; Otsuka: Honoraria; Pfizer Japan: Consultancy; Daiichi Sankyo: Consultancy. Yilmaz:Pint Pharma: Honoraria; Pfizer: Research Funding; Daicho Sankyo: Research Funding. Issa:Syndax: Research Funding; Celegene: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Short:AstraZeneca: Consultancy; Amgen: Honoraria; Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding. Andreeff:Amgen: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy. Cortes:Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sun Pharma: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Telios: Research Funding; Astellas: Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Immunogen: Research Funding; Merus: Research Funding. Ravandi:Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Macrogenics: Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Xencor: Consultancy, Honoraria, Research Funding. Allison:BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAB: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Kantarjian:Cyclacel: Research Funding; BMS: Research Funding; Takeda: Honoraria; Agios: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Astex: Research Funding; AbbVie: Honoraria, Research Funding; Jazz Pharma: Research Funding; Amgen: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immunogen: Research Funding; Novartis: Research Funding; Ariad: Research Funding. Sharma:Achelois: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Apricity Health: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioAlta: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Codiak BioSciences: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Constellation: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Dragonfly Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc.: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Hummingbird: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; ImaginAb: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Jounce Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Lava Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Lytix Biopharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Oncolytics: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Infinity Pharma: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; BioNTech: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Glympse: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Polaris: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Nivolumab and Ipilimumab based combinations for AML, will be discussed. These agents do not have an on label indication for AML at this time.

The inferior cure rate of T-cell acute lymphoblastic leukemia (T-ALL) is associated with inherent drug resistance. The activating NOTCH1 gene mutations have been reported to cause chemoresistance at the stem cell level1. Direct NOTCH1 inhibition has failed in clinical trials due to a narrow therapeutic window but targeting key oncogenic and metabolic pathways downstream of mutated NOTCH1 may offer novel approaches. We previously reported that rapid transformation of thymocytes at the DN3 differentiation stage into preleukemic stem cells (pre-LSC) requires elevated Notch1 in addition to the presence of Scl/Lmo11. Notably, we showed that cellular metabolism of NOTCH1-mutated T-ALLs depends on Oxidative Phosphorylation (OxPhos) and that OxPhos inhibition using the complex I inhibitor IACS-010759 (OxPhos-i) is efficacious in NOTCH1-mutated T-ALL patient derived xenografts (PDXs)2. Here, we investigated the link between NOTCH1-mutated chemoresistance and OxPhos in pre-leukemic and leukemic cells, utilizing comprehensive molecular and functional assays. We hypothesized that chemotherapy aided by OxPhos-i overcomes chemoresistance, depletes LSCs and combats T-ALL. First, we analyzed the role of OxPhos in downstream Notch1 targets at the pre- and leukemic stage considering four stages of thymocyte differentiation (D1-D4), in a mouse model of human T-ALL1. Gene set enrichment analysis (GSEA) implicated increased expression of Notch1 target genes starting at DN1, and OxPhos target genes were the highest-ranked gene set at DN3. Next, activation of Notch1 by its ligand DL4 and inhibition of OxPhos reduced viability of pre-LSCs, indicating that ligand-dependent activation of Notch1 signaling upregulates the OxPhos pathway and sensitizes pre-LSCs to OxPhos-i. To clarify the role of Notch1 signaling, we examined the effect of IACS-010759 on pre-leukemic thymocytes harboring LMO1, SCL-LMO1, NOTCH1, LMO1-NOTCH1 and SCL-LMO1-NOTCH1 with and without DL4 stimulation. We found that in the absence of DL4, only thymocytes harboring the Notch1 oncogene responded to OxPhos-i, whereas all DL4-stimulated thymocytes responded regardless of Notch1 status (Fig. 1a). In addition, at the leukemic stage, we found elevation of the OxPhos pathway driven by oncogenic Notch1 when we compared transcriptomes of SCL-LMO1 induced T-ALL in the presence or absence of the NOTCH1 oncogene. In line with the murine T-ALL NOTCH1 model, we performed transcriptome analysis of two independent T-ALL patient cohorts prior to chemotherapy, COG TARGET ALL (n=263) and AALL1231 (n=75), comparing transcriptomes of NOTCH1-mutated vs NOTCH1-wt T-ALLs. We found co-segregation of NOTCH1 mutations with significant upregulation of OxPhos and TCA cycle genes and downregulation of apoptosis signaling. Aiming to reverse the NOTCH1-controlled anti-apoptotic program and chemoresistance, we next tested the combination of Vincristine, Dexamethasone and L-Asparaginase (VXL) with IACS-010759. When compared to vehicle, OxPhos-i or VXL alone, only the VXL-OxPhos-i treatment caused an energetic crisis indicated by decreased OCR and ECAR (Seahorse), which translated to a profound reduction of viability (CTG, flow cytometry) in T-ALL cell lines (n=9) and primary T-ALL samples (n=5). Additionally, the IACS-VXL combination in vivo resulted in pan-metabolic blockade, which caused metabolic shut-down and triggered early induction of apoptosis in leukemic cells in peripheral blood, spleen and bone marrow (Fig. 1b). Single cell Proteomic analysis (CyTOF) of spleen showed reduced expression of cell proliferation marker -ki67, c-myc, ERK and p38 proteins, and reduction in number of leukemic cells. Finally, this combination therapy resulted in reduced leukemia burden and extension of overall survival across all three aggressive NOTCH1-mutated T-ALL PDX models (p Disclosures Jabbour: Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding. Teachey:Sobi: Consultancy; Amgen: Consultancy; Janssen: Consultancy; La Roche: Consultancy. Rezvani:Takeda: Other: Licensing agreement; GemoAb: Membership on an entity's Board of Directors or advisory committees; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Virogen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Other: Educational grant; Affimed: Other: Educational grant; Formula Pharma: Membership on an entity's Board of Directors or advisory committees. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Lorenzi:Precision Pathways: Consultancy. Konopleva:Calithera: Research Funding; Kisoji: Consultancy; AbbVie: Consultancy, Research Funding; Sanofi: Research Funding; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Cellectis: Research Funding; Rafael Pharmaceutical: Research Funding; Eli Lilly: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Agios: Research Funding; AstraZeneca: Research Funding; Ablynx: Research Funding; Forty-Seven: Consultancy, Research Funding; Amgen: Consultancy; Stemline Therapeutics: Consultancy, Research Funding; Ascentage: Research Funding.

Background : AML is a life-threatening, rapidly progressive malignancy that frequently presents with uncontrolled leukocytosis, organ infiltration, and the need for urgent chemotherapy. Recent advances in genomic profiling have identified significant heterogeneity in AML, that is best addressed with individualized, targeted approaches, often on clinical trials. The requisite cytogenetic and molecular data to inform definite treatment, however, is not rapidly available. Studies have suggested that delaying initial therapy in newly diagnosed AML may worsen OS. Implementing formal cytoreduction strategies may allow time for treatment selection and clinical trial enrollment without adversely affecting outcomes. Methods: We piloted an approach with our frontline clinical trials in AML to allow cytoreductive therapy with hydroxyurea (HA) and/or higher doses of Cytarabine (Ara-C) for disease control prior to definitive therapy. 3 frontline chemotherapy protocols were designed to allow HA and up to 2 grams/m2 of Ara-C for urgent disease control prior to starting therapy. We reviewed the feasibility and outcomes of this approach in older and younger pts with newly diagnosed AML treated between April 2014 and May 2020. Results: We reviewed 276 patients, 97 (35%) which received cytoreductive therapy prior to starting definitive therapy. Baseline characteristics of patients who did or did not receive cytoreductive therapy are summarized in Table 1. The median time from presentation to definitive treatment was 6 days (range 1-21 days) and 6 days (1-46 days) in patients with or without cytoreduction, respectively. Patients with cytoreduction had higher median peripheral blasts 44% (Interquartile Range, IQR : 46-79) vs. 6% (IQR: 4-7) than patients without cytoreduction. More patients with cytoreduction were female (64%; p=0.007), ECOG performance status (PS) >1 (27%; p 1(OR 3.5, 95% CI 1.6-8.0), FLT3 mutation (OR 2.7, p=0.006), female gender (OR 2.4, CI 1.3-4.3) were also associated with a higher likelihood to get cytoreductive therapeutics. Response rates and outcome are summarized in Table 2. There was no difference in rate of CR/CRi (89% vs. 87%; P=0.72) among patients with or without cytoreduction, respectively. Similarly, there was no difference in 30- and 60-day mortality between the groups. When stratified with cytoreduction treatment regimen, there was no significant difference in CR and/or CRi. Of the 16 patients who died within 60 days of diagnosis, only 5 (31%) had documented CR or CRi at the time of death. Median overall survival among patients with or without cytoreduction was 11.3 vs. 11.5 months, respectively (P=0.57) (Figure 1). There remained no difference in OS after adjustment of age, secondary AML, ECOG, ELN, TP53, and type of frontline treatment: Hazard Ratio of 1.1 (95% CI 0.7-1.7). Similarly, there was also no difference in progression free survival between the 2 groups (p=0.59). Conclusions: Pretreatment cytoreductive therapy was safe and feasible in pts with newly diagnosed AML who are in need of urgent therapy, allowing collection of genomic data and enrollment on clinical trials. Despite having higher baseline WBC, blast %, incidence of FLT3 mutations, advanced PS, and higher ELN risk among pts who received cytoreduction, there was no difference in OS, PFS, or early mortality between the 2 groups. These data suggest that urgent cytoreduction may be reasonable alternate option to immediate induction. Disclosures Konopleva: AstraZeneca: Research Funding; AbbVie: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Ascentage: Research Funding; Amgen: Consultancy; Kisoji: Consultancy; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Cellectis: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Sanofi: Research Funding; Rafael Pharmaceutical: Research Funding; Agios: Research Funding; Genentech: Consultancy, Research Funding; Ablynx: Research Funding; Calithera: Research Funding; Eli Lilly: Research Funding; Forty-Seven: Consultancy, Research Funding. DiNardo:MedImmune: Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; ImmuneOnc: Honoraria; Takeda: Honoraria; Calithera: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Jazz: Honoraria; Novartis: Consultancy; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Honoraria, Research Funding; Syros: Honoraria. Borthakur:Treadwell Therapeutics: Consultancy; Nkarta Therapeutics: Consultancy; AstraZeneca: Research Funding; FTC Therapeutics: Consultancy; PTC Therapeutics: Research Funding; Incyte: Research Funding; Abbvie: Research Funding; Jannsen: Research Funding; GSK: Research Funding; BioLine Rx: Research Funding; BMS: Research Funding; Xbiotech USA: Research Funding; Oncoceutics: Research Funding; Curio Science LLC: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; BioTherix: Consultancy; Polaris: Research Funding; Cyclacel: Research Funding; Novartis: Research Funding. Garcia-Manero:Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Consultancy; Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Amphivena Therapeutics: Research Funding; Novartis: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Pemmaraju:Affymetrix: Other: Grant Support, Research Funding; MustangBio: Honoraria; Pacylex Pharmaceuticals: Consultancy; Novartis: Honoraria, Research Funding; Incyte Corporation: Honoraria; Stemline Therapeutics: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; Cellectis: Research Funding; Blueprint Medicines: Honoraria; DAVA Oncology: Honoraria; Plexxikon: Research Funding; SagerStrong Foundation: Other: Grant Support; Roche Diagnostics: Honoraria; Samus Therapeutics: Research Funding; AbbVie: Honoraria, Research Funding; Celgene: Honoraria; Daiichi Sankyo: Research Funding. Daver:Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees. Jabbour:Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding. Yilmaz:Pfizer: Research Funding; Pint Pharma: Honoraria; Daicho Sankyo: Research Funding. Jain:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; ADC Therapeutics: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cellectis: Research Funding; BMS: Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Aprea Therapeutics: Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Short:Astellas: Research Funding; Amgen: Honoraria; Takeda Oncology: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy. Ravandi:Astellas: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Celgene: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Kantarjian:BMS: Research Funding; Pfizer: Honoraria, Research Funding; Astex: Research Funding; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding; Cyclacel: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Research Funding; Novartis: Research Funding; Agios: Honoraria, Research Funding; Ariad: Research Funding; Amgen: Honoraria, Research Funding; Takeda: Honoraria; AbbVie: Honoraria, Research Funding. Kadia:JAZZ: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Cellenkos: Research Funding; Novartis: Honoraria; Amgen: Research Funding; Pulmotec: Research Funding; Astra Zeneca: Research Funding; Abbvie: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Astellas: Research Funding; Pfizer: Honoraria, Research Funding; Celgene: Research Funding; Incyte: Research Funding; Ascentage: Research Funding; Cyclacel: Research Funding.

RUNX1 transcription factor regulates normal and malignant hematopoiesis. Somatic or germline mutant RUNX1 (mtRUNX1) is associated with poorer outcome in acute myeloid leukemia (AML). Knockdown or inhibition of RUNX1 induced more apoptosis of AML expressing mtRUNX1 versus wild-type RUNX1 and improved survival of mice engrafted with mtRUNX1-expressing AML. CRISPR/Cas9-mediated editing-out of RUNX1 enhancer (eR1) within its intragenic super-enhancer, or BET protein BRD4 depletion by short hairpin RNA, repressed RUNX1, inhibited cell growth, and induced cell lethality in AML cells expressing mtRUNX1. Moreover, treatment with BET protein inhibitor or degrader (BET–proteolysis targeting chimera) repressed RUNX1 and its targets, inducing apoptosis and improving survival of mice engrafted with AML expressing mtRUNX1. Library of Integrated Network–based Cellular Signatures 1000–connectivity mapping data sets queried with messenger RNA signature of RUNX1 knockdown identified novel expression-mimickers (EMs), which repressed RUNX1 and exerted in vitro and in vivo efficacy against AML cells expressing mtRUNX1. In addition, the EMs cinobufagin, anisomycin, and narciclasine induced more lethality in hematopoietic progenitor cells (HPCs) expressing germline mtRUNX1 from patients with AML compared with HPCs from patients with familial platelet disorder (FPD), or normal untransformed HPCs. These findings highlight novel therapeutic agents for AML expressing somatic or germline mtRUNX1.

Background: Acute myeloid leukemia (AML) is an epigenetically heterogeneous disease. The intensity of treatment is currently guided by cytogenetic and molecular genetic risk classifications; however these incompletely predict outcomes, requiring additional information for more accurate predictions. We aimed to identify potential prognostic implications of epigenetic modification of histone proteins, with a focus of H3K27 methylation in relation to mutations in chromatin, splicing and transcriptional regulators. Material and methods: Histone methylation mark expressions were evaluated in a cohort of 241 AML bone marrow (BM) and peripheral blood (PB) samples from patients admitted at the MD Anderson Cancer Center relative to their expression in CD34+ BM derived samples from healthy donors. Simultaneous analysis of 230 proteins was performed using the reverse phase protein array - a high-throughput, quantitative proteomic platform that enables identification of aberrant expressed proteins and the pathways they act in. Additional mutational analysis was performed on 65 BM samples. Results:H3K27Me3 was significantly lower in both BM and PB leukemic-derived samples compared to their expression in normal BM (figure 1A). A greater loss of H3K27Me3 associated with increased proliferative potential and shorter overall survival (OS) in the whole patient population (n=241, HR=0.64, 95% CI=0.47-0.87, p A total of 78 AML patients had molecular data available for the major methylation affecting genes, i.e. IDH1, IDH2, DNMT3A and TET2. The level of H3K27Me3 was not prognostic in patients without any DNA methylation affecting mutation present, but patients with at least one mutation in any of these had better outcome when H3K27Me3 levels were high (highest tertile, figure 1A) compared to those with lower levels (median OS 7.1 vs. 24.1 months, HR=0.42, 95% CI=0.21-0.83, p=0.01, figure 1B). Mutations in U2AF1 and SRSF2 affect the spliceosome and are frequently found in antecedent hematological disorders (AHD), as well as are mutations in chromatin regulating genes ASXL1 and BCOR. We observed significant decreased H3K27Me3 in patients with these mutations corresponding with observed lower levels of H3K27Me3 in patients with AHD than those without (p=0.035). BCOR, SRSF2, U2AF1 and ASXL1 mutations confer poor prognosis in myeloid malignancies, however, in our cohort of 65 sequenced AML patients; not individual or a combination of these mutations were independent prognostic factors, but the degree of H3K27Me3 in these patients (HR= 0.49, 95% CI=0.25-0.95, p=0.03). To recognize dysregulated pathways in AML patients with the identified loss of H3K27Me3, we examined correlations of H3K27Me3 with the other 229 proteins on the array. H3K27Me3 is catalyzed by the polycomb group protein EZH2 and is linked to transcriptional repression via the formation of heterochromatin regions. To identify upregulated proteins and pathways upon the loss of H3K27Me3, we focused on significant negatively correlated proteins with H3K27Me3 leading us to the identification of 20 total and 6 phospho-proteins that showed increased expression upon decreased H3K27Me3. Functional enrichment analysis of this protein set revealed an upregulated anti-apoptotic phenotype. Conclusion:This study shows that proteomic profiling of epigenetic modifications on the histone level have clinical implications in AML and support the idea that epigenetic patterns contribute to a more accurate picture of the leukemic state complementing cytogenetic and molecular genetic subgrouping. Figure 1. A) Lower H3K27Me3 in BM and PB derived AML samples compared to normal CD34+. **** represents p Figure 1 Disclosures No relevant conflicts of interest to declare.

Background: DEC10-VEN is an effective regimen and offers better outcomes compared to intensive chemotherapy in older pts with newly diagnosed (ND) or relapsed/refractory (R/R) AML (Maiti. Am J Hematol 2021; Maiti. Cancer 2021). We report long term outcomes in major genomic subgroups. Methods: Pts received decitabine 20 mg/m 2 on D1-10 until CR/CRi, followed by 5-day cycles. VEN dose was 400 mg daily but held on C1D21 if D21 bone marrow (BM) had ≤5% blasts. VEN could be reduced to Concomitant TKIs included gilteritinib (18), sorafenib (13), midostaurin (5), enasidenib (3) and ponatinib (1). Eligible pts could proceed to stem cell transplantation (SCT) after response. Endpoints were defined per ELN2017. NGS targeting entire coding regions of 81 myeloid genes was performed on screening BM sample with an analytical sensitivity of 5%. Measurable residual disease (MRD) was tested by multiparametric flow cytometry (sensitivity 0.1%). Results: Between January 2018 and April 2021 we enrolled 199 pts with ND AML (n=83), untreated sAML (n=20), treated sAML (n=25), and R/R AML (n=71). Median age of treatment-naïve pts was 72 yrs (range 61-72) and of previously treated pts was 67 yrs (range 18-85, Table 1). No pts had favorable risk cytogenetics. Median no. of prior therapies in previously treated pts was 2 (range 1-8) and 24% pts (23/96) had prior SCT. 21 treatment-naïve and 20 previously treated pts underwent SCT after response. Median follow-up for all pts was 25.4 mo. Among treatment-naïve pts, CR/CRi rates were high in all mutations subgroups ranging from 70-88% in pts with NPM1mut, FLT3mut, IDH1/2mut, TP53mut, RUNX1mut, K/NRASmut. Pts with ASXL1mut had modest CR/CRi rate of 56% (Table 2). FLT3 TKI was used in 71% FLT3mut pts (n=15/21). MRD negative rate among responding pts were high across all mutational subgroups ranging from 62-91%, except 55% in pts with ASXL1mut and 50% in pts with TP53mut. Median overall survival (OS) for treatment-naïve pts with NPM1mut was not reached (NR), IDH1/2mut was 29.6 mo, FLT3mut was 24.5 mo, RUNX1mut was 16.2 mo, ASXL1mut was 15.2 mo, K/NRASmut was 12.1 mo and TP53mut was 5.4 mo (Fig 1a-b). The median relapse-free survival (RFS) among treatment-naïve pts with NPM1mut was NR, IDH1/2mut was NR, FLT3mut was 20.0 mo, RUNX1mut was 9.7 mo, ASXL1mut was 8.5 mo, K/NRASmut was 6.5 mo and TP53mut was 3.1 mo (Fig 1c-d). Among NPM1+FLT3 co-mutated pts, outcomes in treatment-naïve pts (n=26) included ORR of 96%, CR/CRi in 88%, MRD negative in 92% (22/24), median OS NR and median RFS NR. Among previously treated NPM1+FLT3 pts (n=9), ORR was 78%, CR/CRi in 56%, MRD negative in 86% (6/7), median OS 12.4 mo and median RFS 6.6 mo. Among NPM1+DNMT3A co-mutated pts, outcomes in treatment-naïve pts (n=28) included ORR of 93%, CR/CRi in 89%, MRD negative in 79% (19/24), median OS 15.2 mo and median RFS 9.0 mo. Among previously treated NPM1+DNMT3A pts (n=6), ORR was 75%, CR/CRi in 50%, MRD negative in 75% (3/4), median OS was 4.7 mo and median RFS was 5.2 mo. Among previously treated pts CR/CRi rates in pts with NPM1mut was 68%, IDH1/2mut 50%, FLT3mut 42%, RUNX1mut 45%, ASXL1mut 38%, TP53mut 30%, and K/NRASmut was 26% (Table 2). FLT3 TKI used in 95% of FLT3mut pts (n=18/19). MRD negative rate among responding pts were high for pts with NPM1mut, FLT3mut, IDH1/2mut, RUNX1mut and ASXL1mut ranging from 60-87%, but were low for pts with K/NRASmut at 56% and TP53mut at 37%. The median OS among previously treated pts with IDH1/2mut was 16.9 mo, RUNX1mut was 13.7 mo, NPM1mut was 12.4 mo, ASXL1mut was 9.0 mo, FLT3mut was 6.4 mo, K/NRASmut was 6.0 mo, and for TP53mut was 4.5 mo (Fig 1e-f). The median RFS among treatment-naïve pts with K/NRASmut was 18.9 mo, NPM1mut was 15.6 mo, IDH1/2mut was 15.3, RUNX1mut was 12.9 mo, ASXL1mut was 10.7 mo, TP53mut was 9.4 mo, and for FLT3mut was 6.6 mo (Fig 1g-h). Conclusions: DEC10-VEN offered high rates of CR/CRi, negative MRD, favorable OS and RFS across several genomic subgroups of treatment-naïve AML including NPM1, FLT3, IDH1/2 and modest outcomes in pts with these mutations in salvage setting. Outcomes in pts with TP53, RUNX1, ASXL1 and K/NRAS were suboptimal. Outcomes with FLT3 VEN HMA triplet was encouraging, particularly for frontline FLT3mut pts. Figure 1 Figure 1. Disclosures DiNardo: Novartis: Honoraria; Takeda: Honoraria; ImmuneOnc: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Agios/Servier: Consultancy, Honoraria, Research Funding; Foghorn: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Forma: Honoraria, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Pemmaraju: Affymetrix: Consultancy, Research Funding; Cellectis S.A. ADR: Other, Research Funding; Samus: Other, Research Funding; Blueprint Medicines: Consultancy; Celgene Corporation: Consultancy; Clearview Healthcare Partners: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Protagonist Therapeutics, Inc.: Consultancy; Aptitude Health: Consultancy; Incyte: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; LFB Biotechnologies: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Plexxicon: Other, Research Funding; CareDx, Inc.: Consultancy; Daiichi Sankyo, Inc.: Other, Research Funding; Springer Science + Business Media: Other; DAVA Oncology: Consultancy; Roche Diagnostics: Consultancy; MustangBio: Consultancy, Other; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Daver: Amgen: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Sevier: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Hanmi: Research Funding; Genentech: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Novimmune: Research Funding; Glycomimetics: Research Funding; Trillium: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Issa: Syndax Pharmaceuticals: Research Funding; Novartis: Consultancy, Research Funding; Kura Oncology: Consultancy, Research Funding. Borthakur: Astex: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; University of Texas MD Anderson Cancer Center: Current Employment; Ryvu: Research Funding; Protagonist: Consultancy; Takeda: Membership on an entity's Board of Directors or advisory committees; ArgenX: Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy. Ravandi: Taiho: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Xencor: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Prelude: Research Funding; AbbVie: Honoraria, Research Funding; AstraZeneca: Honoraria; Novartis: Honoraria; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding. Alvarado: BerGenBio: Research Funding; Jazz Pharmaceuticals: Research Funding; Sun Pharma: Consultancy, Research Funding; MEI Pharma: Research Funding; FibroGen: Research Funding; CytomX Therapeutics: Consultancy; Daiichi-Sankyo: Research Funding; Astex Pharmaceuticals: Research Funding. Kadia: BMS: Other: Grant/research support; Dalichi Sankyo: Consultancy; Cure: Speakers Bureau; Jazz: Consultancy; Liberum: Consultancy; Aglos: Consultancy; Amgen: Other: Grant/research support; Novartis: Consultancy; AbbVie: Consultancy, Other: Grant/research support; Genentech: Consultancy, Other: Grant/research support; Pfizer: Consultancy, Other; Pulmotech: Other; Sanofi-Aventis: Consultancy; Cellonkos: Other; Ascentage: Other; Genfleet: Other; Astellas: Other; AstraZeneca: Other. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Short: Novartis: Honoraria; Jazz Pharmaceuticals: Consultancy; NGMBio: Consultancy; Astellas: Research Funding; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Jain: Adaptive Biotechnologies: Honoraria, Research Funding; Janssen: Honoraria; Aprea Therapeutics: Research Funding; Genentech: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Precision Biosciences: Honoraria, Research Funding; Fate Therapeutics: Research Funding; Servier: Honoraria, Research Funding; ADC Therapeutics: Honoraria, Research Funding; TG Therapeutics: Honoraria; Beigene: Honoraria; Incyte: Research Funding; Cellectis: Honoraria, Research Funding; Pfizer: Research Funding; AstraZeneca: Honoraria, Research Funding; Pharmacyclics: Research Funding; AbbVie: Honoraria, Research Funding. Wierda: Juno Therapeutics: Research Funding; KITE Pharma: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Cyclacel: Research Funding; Loxo Oncology, Inc.: Research Funding; Acerta Pharma Inc.: Research Funding; Genzyme Corporation: Consultancy; Miragen: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Sunesis: Research Funding; GSK/Novartis: Research Funding; Genentech: Research Funding; Gilead Sciences: Research Funding; Xencor: Research Funding; Janssen: Research Funding; Karyopharm: Research Funding; AbbVie: Research Funding; AstraZeneca: Research Funding. Sasaki: Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees. Takahashi: GSK: Consultancy; Celgene/BMS: Consultancy; Symbio Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy. Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Burger: Beigene: Research Funding, Speakers Bureau; Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Verstovsek: Incyte Corporation: Consultancy, Research Funding; PharmaEssentia: Research Funding; Promedior: Research Funding; AstraZeneca: Research Funding; NS Pharma: Research Funding; Ital Pharma: Research Funding; Celgene: Consultancy, Research Funding; Protagonist Therapeutics: Research Funding; Roche: Research Funding; Sierra Oncology: Consultancy, Research Funding; Gilead: Research Funding; Genentech: Research Funding; CTI BioPharma: Research Funding; Blueprint Medicines Corp: Research Funding; Novartis: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy. Andreeff: Karyopharm: Research Funding; Syndax: Consultancy; Medicxi: Consultancy; Oxford Biomedica UK: Research Funding; Amgen: Research Funding; ONO Pharmaceuticals: Research Funding; Glycomimetics: Consultancy; Novartis, Cancer UK; Leukemia & Lymphoma Society (LLS), German Research Council; NCI-RDCRN (Rare Disease Clin Network), CLL Foundation; Novartis: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Research Funding; Breast Cancer Research Foundation: Research Funding; Aptose: Consultancy; Senti-Bio: Consultancy; AstraZeneca: Research Funding; Reata, Aptose, Eutropics, SentiBio; Chimerix, Oncolyze: Current holder of individual stocks in a privately-held company. Bose: CTI BioPharma: Honoraria, Research Funding; Incyte Corporation: Honoraria, Research Funding; Astellas: Research Funding; Kartos Therapeutics: Honoraria, Research Funding; Sierra Oncology: Honoraria; NS Pharma: Research Funding; Celgene Corporation: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Blueprint Medicines: Honoraria, Research Funding; Novartis: Honoraria; Constellation Pharmaceuticals: Research Funding; Pfizer: Research Funding; Promedior: Research Funding. Ferrajoli: BeiGene: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board ; AstraZeneca: Other: Advisory Board, Research Funding. Thompson: Gilead: Other: Institution: Advisory/Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Amgen: Other: Institution: Honoraria, Research Grant/Funding. Welch: Janssen: Research Funding; Notable Labs: Research Funding. Kantarjian: Ipsen Pharmaceuticals: Honoraria; Immunogen: Research Funding; Pfizer: Honoraria, Research Funding; Aptitude Health: Honoraria; Jazz: Research Funding; NOVA Research: Honoraria; KAHR Medical Ltd: Honoraria; Astellas Health: Honoraria; Daiichi-Sankyo: Research Funding; BMS: Research Funding; AbbVie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Astra Zeneca: Honoraria; Amgen: Honoraria, Research Funding; Ascentage: Research Funding; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. Konopleva: Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Ascentage: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Cellectis: Other: grant support; KisoJi: Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Sanofi: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding. OffLabel Disclosure: Off-label use - venetoclax in relapsed/refractory AML

Chronic myeloid leukemia (CML) accounts for 2-9% of leukemias in children and adolescents, and occurs with much greater frequency in adults. Compared to adults, children with CML tend to present with higher white blood cell counts and larger spleens, suggesting that the biology of pediatric CML is different from adult CML. We hypothesize that the differences in clinical presentation of pediatric CML are due to unique molecular characteristics that differ from adult CML. To test this hypothesis, we compared the transcriptomic signature of pediatric and adult CML CD34+ cells and healthy age-matched CD34+ cells. CD34+ cells were isolated by FACS from pediatric CML (n=9), adult CML (n=10), pediatric healthy (n=10), and adult healthy (n=10) bone marrow samples. Prepared libraries were sequenced on the Illumina HiSeq 4000 instrument. Raw sequences were trimmed and aligned to the hg38 reference genome with STAR/2.5.1b aligner. Gene level counts were determined with STAR -quantMode option using gene annotations from GENCODE (p5). Differential gene expression and pathway analysis were conducted with R/3.5.3. Counts were normalized with trimmed mean of M-values from the EdgeR/ 3.24.3 package and further transformed with VOOM from the Limma/ 3.38.3 package. A linear model using the empirical Bayes analysis pipeline also from Limma was then used to obtain p-values, adjusted p-values and log-fold changes. Four comparisons were performed: (1) pediatric CML vs pediatric healthy, (2) adult CML vs adult healthy, (3) pediatric CML vs adult CML, and (4) pediatric healthy vs adult healthy. A False Discovery Rate of ≤ .05 and absolute log2 fold-change > 1 was used to define differentially expressed genes (DEGs) in each comparison. To identify potentially unique pathways based on DEG, pathway over-representation was calculated with either goana from the limma package or clueGO. At diagnosis, pediatric patients had higher platelet counts (p=0.001) and larger spleen sizes (p=0.010) than adult patients. Median WBC counts were 273,000 and 143,000 in pediatric and adult patients respectively. A total of 1352 genes were differentially expressed in either adult or pediatric CML CD34+ cells compared to healthy CD34+ cells, 174 of which were expressed similarly in pediatric and adult CML CD34+ cells (54 up- and 120 down-regulated). There were 746 differentially expressed genes (325 up- and 421 down-regulated) in adult CML CD34+ cells compared to adult healthy CD34+ cells, and 432 differentially expressed genes (156 up- and 276 down-regulated) in pediatric CML CD34+ cells compared to pediatric healthy CD34+ cells. In direct comparison of pediatric and adult CML CD34+ cells, 446 genes (270 up and 176 down) were dysregulated in pediatric CML CD34+ cells. Pathway analysis showed that Rho signaling pathway was downregulated in pediatric CML CD34+ cells and several genes in Rho pathway were uniquely dysregulated. ARHGAP27 and VAV2 were significantly upregulated in adult CML CD34+ cells by 3.7-fold (p=0.0453) and 11-fold (p=0.0072), respectively, compared to pediatric CML CD34+ cells. In addition, several genes involved in the NADPH oxidase pathway, one of the best-characterized Rho GTPase-regulated systems, were differently expressed in CML. NCF1, CYBB, and S100A8 were significantly upregulated in adult CML CD34+ cells by 4-fold (p=0.0045), 3.26-fold (p These results demonstrate unique molecular characteristics of pediatric CML that may contribute to the clinical differences at presentation between adult and pediatric disease. A better understanding of the molecular biology of CML across the ages will provide new insights into the pathogenesis of pediatric CML and potentially inform future treatment decisions. Disclosures Davis: Jazz Pharmaceuticals: Research Funding; Novartis Pharmaceuticals: Honoraria. Hijiya: Novartis: Consultancy; Stemline Therapeutics: Consultancy.

Background: Inotuzumab ozogamicin (INO) and blinatumomab are effective in the treatment relapsed/ refractory B-cell acute lymphoblastic leukemia (ALL) and improve overall survival (OS) in this setting. The use of these agents in older adults with newly diagnosed B-cell ALL may allow for use of less chemotherapy and improve remission durations and OS compared to standard therapies. Methods: Patients (pts) ≥60 years of age with newly diagnosed Philadelphia chromosome (Ph)-negative pre-B-cell ALL were eligible. Pts were required to have a performance status of ≤3, total bilirubin ≤1.5 mg/dl, AST/ALT ≤3x ULN and creatinine ≤2 mg/dl. Pts received mini-hyper-CVD (cyclophosphamide and dexamethasone at 50% dose reduction, no anthracycline, methotrexate at 75% dose reduction, cytarabine at 0.5 g/m 2 x 4 doses) for up to 8 cycles. INO was given at a dose of 1.3-1.8mg/m 2 on day 3 of cycle 1 and 0.8-1.3mg/m 2 on day 3 of cycles 2-4. Rituximab (if CD20+) and prophylactic IT chemotherapy were given for the first 4 cycles. Responding pts received POMP maintenance for up to 3 years. In order to decrease the risk of veno-occlusive disease (VOD), the protocol was amended in 3/2017 (pts 50+) to give INO in fractionated doses each cycle (0.6 mg/m 2 on day 2 and 0.3 mg/m 2 on day 8 of cycle 1; 0.3 mg/m 2 on day 2 and 8 of cycles 2-4) and to administer 4 cycles of blinatumomab following 4 cycles of hyper-CVD plus INO, followed by maintenance with 12 cycles of POMP and 4 cycles of blinatumomab (1 cycle of blinatumomab after every 3 cycles of POMP). The cumulative dose of INO given before and after this most recent amendment was 4.3 mg/m 2 and 2.7 mg/m 2, respectively. Results: 75 pts have been treated. 6 pts were in complete remission (CR) at enrollment and unevaluable for morphological response. Pt characteristics are summarized in Table 1. Median age was 68 years (range, 60-87 years); 30 pts (40%) were ≥70 years. 39% were positive for TP53 mutation, 19% had Ph-like ALL (with 6 of the 8 Ph-like pts being CRLF2+ by flow), and 25% had adverse-risk karyotype. Among 69 pts evaluable for morphologic response, 68 (99%) responded (CR, n=61; CRp, n=6; CRi, n=1). MRD negativity by flow cytometry was achieved in 57/71 pts (80%) after 1 cycle and 71/74 pts (96%) overall. The 30-day and 60-day mortality rates were 0% and 3%, respectively. Among 74 pts who achieved remission, 10 (14%) relapsed, 4 (5%) underwent allogeneic SCT in first remission (1 of whom subsequently relapsed), 32 (43%) remain on treatment or have completed therapy, and 28 (38%) died in remission. Overall, 9 pts (12%) developed MDS/AML; in 7 of these cases the myeloid malignancy was TP53-mutated and in the 2 other cases, both the ALL and subsequent AML shared mutations in myeloid mutations (RUNX1, SRSF2, and TET2). Notably, 6 pts (8%) developed VOD, 1 after subsequent allogeneic SCT. The rate of VOD was 6/75 (8%) with no difference in VOD in pts who did or did not receive blinatumomab. With a median follow-up of 56 months (range, 1-111 months), the 5-year continuous remission and OS rates were 76% and 47%, respectively (Figure 1A). Outcomes were superior for those 60-69 years of age versus those who were ≥70 years (5-year OS rates: 58% and 31%, respectively; P=0.04) and for those without poor-risk cytogenetics (e.g. KMT2A rearranged, low hypodiploidy/near triploidy, complex cytogenetics) versus poor-risk cytogenetics (5-year OS rates: 56% and 25%, respectively; P=0.01). Pts ≥70 years of age were more likely to die in remission (20/29 [69%] vs. 19/45 [42%] in pts 60-69 years of age; P=0.03), which was a major driver of the poor survival in this age group. The 5-year OS for pts age 60-69 years with non-poor risk cytogenetics, age 60-69 with poor risk cytogenetics, age ≥70 with non-poor risk cytogenetics and age ≥70 with poor risk cytogenetics were 68%, 37%, 42% and 0% respectively (Figure 1B). Neither Ph-like ALL nor the presence of a TP53 mutation significantly impacted OS (P=0.26 and P=0.34, respectively). Conclusion: Low-intensity chemotherapy with hyper-CVD plus INO, with or without blinatumomab, in older adults with newly diagnosed Ph-negative ALL resulted in an overall response rate of 98% and a 5-year OS rate of 47%. Even with this relatively reduced-intensity regimen, deaths in remission (usually due to infection) occur, primarily in pts ≥70 years of age. A strategy using the combination INO and blinatumomab, without any chemotherapy, is being explored in this population. Figure 1 Figure 1. Disclosures Short: NGMBio: Consultancy; Astellas: Research Funding; AstraZeneca: Consultancy; Novartis: Honoraria; Jazz Pharmaceuticals: Consultancy; Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Kantarjian: BMS: Research Funding; Aptitude Health: Honoraria; NOVA Research: Honoraria; Astra Zeneca: Honoraria; AbbVie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Immunogen: Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Astellas Health: Honoraria; Jazz: Research Funding; Daiichi-Sankyo: Research Funding; Ipsen Pharmaceuticals: Honoraria; KAHR Medical Ltd: Honoraria; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. Ravandi: Novartis: Honoraria; AbbVie: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Xencor: Honoraria, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding; Astex: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Prelude: Research Funding; Amgen: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Taiho: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria. Jain: Janssen: Honoraria; TG Therapeutics: Honoraria; Beigene: Honoraria; Precision Biosciences: Honoraria, Research Funding; Servier: Honoraria, Research Funding; Incyte: Research Funding; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; AstraZeneca: Honoraria, Research Funding; ADC Therapeutics: Honoraria, Research Funding; Pfizer: Research Funding; Adaptive Biotechnologies: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Cellectis: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Pharmacyclics: Research Funding. Kadia: Genfleet: Other; AstraZeneca: Other; Genentech: Consultancy, Other: Grant/research support; Jazz: Consultancy; AbbVie: Consultancy, Other: Grant/research support; Cure: Speakers Bureau; Aglos: Consultancy; Sanofi-Aventis: Consultancy; Pulmotech: Other; Dalichi Sankyo: Consultancy; BMS: Other: Grant/research support; Cellonkos: Other; Pfizer: Consultancy, Other; Astellas: Other; Ascentage: Other; Novartis: Consultancy; Liberum: Consultancy; Amgen: Other: Grant/research support. Khoury: Kiromic: Research Funding; Stemline Therapeutics: Research Funding; Angle: Research Funding. Wang: Stemline Therapeutics: Honoraria. Alvarado: Astex Pharmaceuticals: Research Funding; MEI Pharma: Research Funding; Daiichi-Sankyo: Research Funding; FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; CytomX Therapeutics: Consultancy; BerGenBio: Research Funding; Sun Pharma: Consultancy, Research Funding. Burger: Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau; Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Beigene: Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Daver: Bristol Myers Squibb: Consultancy, Research Funding; Novimmune: Research Funding; Glycomimetics: Research Funding; Hanmi: Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy; Trovagene: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Borthakur: University of Texas MD Anderson Cancer Center: Current Employment; Astex: Research Funding; GSK: Consultancy; ArgenX: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Protagonist: Consultancy; Ryvu: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees. DiNardo: Bristol Myers Squibb: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; ImmuneOnc: Honoraria, Research Funding; Forma: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Foghorn: Honoraria, Research Funding; Agios/Servier: Consultancy, Honoraria, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Konopleva: AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Cellectis: Other: grant support; Calithera: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; KisoJi: Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Stemline Therapeutics: Research Funding; AstraZeneca: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Ascentage: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding. Pemmaraju: Daiichi Sankyo, Inc.: Other, Research Funding; Springer Science + Business Media: Other; LFB Biotechnologies: Consultancy; Celgene Corporation: Consultancy; Protagonist Therapeutics, Inc.: Consultancy; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Samus: Other, Research Funding; Plexxicon: Other, Research Funding; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; MustangBio: Consultancy, Other; Incyte: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; DAVA Oncology: Consultancy; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Cellectis S.A. ADR: Other, Research Funding; Affymetrix: Consultancy, Research Funding; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Clearview Healthcare Partners: Consultancy; Roche Diagnostics: Consultancy; Sager Strong Foundation: Other; Aptitude Health: Consultancy; CareDx, Inc.: Consultancy; Blueprint Medicines: Consultancy; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Wierda: Miragen: Research Funding; GSK/Novartis: Research Funding; Loxo Oncology, Inc.: Research Funding; Acerta Pharma Inc.: Research Funding; Karyopharm: Research Funding; Janssen: Research Funding; Juno Therapeutics: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Gilead Sciences: Research Funding; Genentech: Research Funding; AstraZeneca: Research Funding; Xencor: Research Funding; Cyclacel: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Sunesis: Research Funding; KITE Pharma: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding. O'Brien: Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding; Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. OffLabel Disclosure: Blinatumomab and inotuzumab as frontline therapy for B-cell ALL

Introduction: The endoplasmic reticulum (ER) is the major site of protein synthesis and folding in the cell. Three pathways are integrated to maintain ER homeostasis: ER-associated degradation (ERAD), unfolded protein response (UPR), and autophagy. One of the chief elements of ERAD is the highly conserved AAA-ATPase superfamily member valosin-containing protein (VCP, or p97). Various studies have reported an upregulation of VCP in cancer and an association between elevated VCP expression and unfavorable cancer outcome. A promising therapeutic approach relies on targeting the cellular stress response, and systemic functional genomic screens have identified VCP as potential target for inhibition in acute myeloid leukemia (AML). As clinical impact of VCP has not been studied, we wondered whether baseline protein expression levels were predictive of outcome in acute leukemia (AL). Methods: Reverse Phase Protein Array (RPPA) was performed with strictly validated antibodies, including antibodies against VCP, IRE1 and GRP78, to determine the protein expression levels of diagnostic leukemic cells from 500 pediatric AML, 818 adult AML, 268 pediatric T-ALL and 93 adult T-ALL patient samples. Pediatric patients participated on either the COG AAML1031 or AALL1231 clinical trial comparing standard therapy (ADE or AFBM) to standard therapy plus bortezomib (ADE+B or AFBM+B). Adults were treated under a variety of protocols. Pearson correlation analyses was used to identify significant protein-protein correlations. Estimates of survival was calculated using the Kaplan-Meier method. Results: VCP protein was expressed in both AML and T-ALL. Although VCP was slightly more highly expressed in AL vs normal CD34+ cells, the majority of patients had VCP expression within the normal range. In pediatric AML, VCP was more highly expressed in younger patients (< 2 y/o), KMT2A (formerly MLL)-rearrangement (p Conclusion: Using a proteomics approach we identified low-VCP as favorable prognostic indicator. This prognostic association was independent of treatment with a proteasome inhibitor, suggesting that the prognostic effect was potentially separate from the proteasome, and points toward a potential for VCP drug inhibition. Negative correlation with VCP and IRE1 and GRP78 might imply that cells with higher VCP rely on proteasomal degradation, whereas those with low VCP are more dependent on other pathways for protein degradation. Also, adaptation in VCP levels may not be a prominent feature of the stress response to chemotherapy. More information is needed to understand what is driving VCP expression. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: Addition of the FLT3 inhibitor midostaurin to intensive chemotherapy is the standard of care for newly diagnosed FLT3-mutated AML. Gilteritinib is a 2nd generation FLT-3 inhibitor approved for patients with relapsed/refractory (R/R) FLT3-mutated AML. We studied the combination of gilteritinib with a higher-dose araC-based regimen of Cladribine, Idarubicin, Cytarabine (CLIA) in patients with FLT3-mutated AML. Methods: Patients aged 18-65 years, fit for intensive chemotherapy, with newly diagnosed FLT3-mutated AML were enrolled. Induction was: Cladribine 5 mg/m 2 IV on days 1-5, Cytarabine 1.5-2.0 g/m 2 IV on days 1-5, Idarubicin 10 mg/m 2 IV on days 1-3 and gilteritinib on days 1-14. Consolidation consisted of up to 5 more cycles of CLIA: cladribine 5 mg/m 2 IV on days 1-3, Cytarabine 750 mg/m 2 IV on days 1-3, and idarubicin 8 mg/m 2 IV on days 1-2 with gilteritinib 120 mg continuously during cycle 2 onward. An additional cohort studied the addition of venetoclax CLIA + gilteritinib. In this cohort, venetoclax was added days 1-7 of each cycle at a target dose of 400mg daily, with dose adjustments for concomitant CYP3A inhibitors. Results: Eighteen patients were enrolled, with a median age of 56 years (range, 39-63). 15 pts (83%) had FLT3-ITD, 5 pts (27%) had FLT3 D835, and 2 pts (11%) had both. The median allelic ratio of FLT3-ITD was 0.36 (0.06-1.45) and of FLT3 D835 was 0.15 (.05-.084 Patient characteristics and outcomes are outlined in TABLE 1. Fifteen patients (83%) had diploid cytogenetics, one patient with -5, one with trisomy 8, one with Inv (16) and one patient with complex karyotype. The most commonly co-occurring mutations were: NPM1 (67%), TET2 (33%), ASXL1 (33%), and DNMT3A (33%), KDM6A (27%). Ten patients (56%) received CLIA + gilteritinib and 8 patients (44%) received CLIA + gilteritinib + venetoclax. 13 out of 18 pts (72%) achieved complete remission (CR). The rate of CR / CRi was 83%, including 8/10 pts (80%) in the CLIA + gilteritinib cohort and 7/8 pts (88%) in the CLIA + gilteritnib + venetoclax cohort. The median number of cycles to response was one (x-y). Patients received a median of 2 cycles (1-3) of therapy on protocol. The 4- and 8-week mortality rate was 6% (one patient in the venetoclax cohort, no early mortality with CLIA + gilteritinib). The most common adverse effects were: Neutropenic fever (12/18, 67%), Grade 2-3 ALT elevation in (3/18, 17%), grade 3 Headache (1/18, 6%) and grade 3 diarrhea (1/18, 6%). The median time to neutrophil ≥ 0.5 K/uL was 33 days (26-40) and 38 days (30-40) for the CLIA-gilteritinib and CLIA-gilteritinib-venetoclax cohorts. The median time to neutrophil ≥ 1 K/uL was 36.5 days (26-48) and 40 days (31-45) for the CLIA-gilteritinib and CLIA-gilteritinib-venetoclax cohorts, respectively. The median time to platelet ≥ 100 K/uL was 34.5 days (24-48) and 40 days (34-45) for 2 cohorts, respectively. Twelve of fifteen responding patients (80%) had undetectable minimal residual disease (MRD) tested by multiparameter flow cytometry by the time of response: 7/8 (88%) of the CLIA + Gilteritinib cohort and 5/7 patients (71%) of the CLIA + gilteritnib + venetoclax. Additionally, 13/15 patients (87%) had no detectable FLT3 mutation by PCR at time of response (7/8 patients (88%) of the CLIA + Gilteritinib cohort and 6/7 patients (86%) of the CLIA + gilteritnib + venetoclax cohort). The median overall survival for the entire cohort was 21.95 months (not reached for the CLIA + gilteritnib cohort and 22.4 months for the CLIA + gilteritnib+ venetoclax cohort) (Figures 1 and 2). Eleven of the 15 responding patients (73%) underwent to allogenic stem cell transplantation in CR1 (7 and 4 patients in the CLIA + gilteritnib and the CLIA + Gilteritinib + venetoclax cohort respectively). Conclusion: The combination of the FLT3 inhibitor gilteritinib to CLIA produced high rates of complete remission in patients with newly diagnosed FLT3-mutated AML. The addition of venetoclax to the backbone was associated with similar outcomes but prolonged count recovery. The combination resulted in high rates of MRD negativity by flow and molecular testing at the time of response. Further study of the combination of CLIA + gilteritinib in fit patients with newly diagnosed FLT3-mutated AML patients is planned. Figure 1 Figure 1. Disclosures Kantarjian: KAHR Medical Ltd: Honoraria; Astra Zeneca: Honoraria; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding; Novartis: Honoraria, Research Funding; NOVA Research: Honoraria; Pfizer: Honoraria, Research Funding; Jazz: Research Funding; Ascentage: Research Funding; Ipsen Pharmaceuticals: Honoraria; AbbVie: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Precision Biosciences: Honoraria; Aptitude Health: Honoraria; Astellas Health: Honoraria; BMS: Research Funding; Taiho Pharmaceutical Canada: Honoraria. Alvarado: Daiichi-Sankyo: Research Funding; MEI Pharma: Research Funding; Sun Pharma: Consultancy, Research Funding; CytomX Therapeutics: Consultancy; FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; BerGenBio: Research Funding; Astex Pharmaceuticals: Research Funding. Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Pemmaraju: LFB Biotechnologies: Consultancy; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; MustangBio: Consultancy, Other; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Plexxicon: Other, Research Funding; DAVA Oncology: Consultancy; Celgene Corporation: Consultancy; Roche Diagnostics: Consultancy; Affymetrix: Consultancy, Research Funding; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Sager Strong Foundation: Other; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Clearview Healthcare Partners: Consultancy; CareDx, Inc.: Consultancy; Samus: Other, Research Funding; Daiichi Sankyo, Inc.: Other, Research Funding; Springer Science + Business Media: Other; Incyte: Consultancy; Aptitude Health: Consultancy; Cellectis S.A. ADR: Other, Research Funding; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Daver: ImmunoGen: Consultancy, Research Funding; Hanmi: Research Funding; Genentech: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Abbvie: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Novartis: Consultancy; Bristol Myers Squibb: Consultancy, Research Funding; Glycomimetics: Research Funding; Novimmune: Research Funding; Pfizer: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Burger: TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau; Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; AstraZeneca: Consultancy; Beigene: Research Funding, Speakers Bureau; Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Jain: Aprea Therapeutics: Research Funding; Cellectis: Honoraria, Research Funding; Genentech: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Incyte: Research Funding; Janssen: Honoraria; Beigene: Honoraria; Servier: Honoraria, Research Funding; ADC Therapeutics: Honoraria, Research Funding; Fate Therapeutics: Research Funding; Adaptive Biotechnologies: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Pfizer: Research Funding; TG Therapeutics: Honoraria; Precision Biosciences: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Pharmacyclics: Research Funding. DiNardo: Takeda: Honoraria; ImmuneOnc: Honoraria, Research Funding; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Forma: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Foghorn: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Agios/Servier: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Borthakur: Ryvu: Research Funding; Protagonist: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; ArgenX: Membership on an entity's Board of Directors or advisory committees; Astex: Research Funding; University of Texas MD Anderson Cancer Center: Current Employment; GSK: Consultancy. Ravandi: Prelude: Research Funding; AbbVie: Honoraria, Research Funding; Astex: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Taiho: Honoraria, Research Funding; Xencor: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Honoraria; Novartis: Honoraria. Kadia: Ascentage: Other; Genfleet: Other; Cellonkos: Other; Pfizer: Consultancy, Other; AstraZeneca: Other; Novartis: Consultancy; Sanofi-Aventis: Consultancy; Astellas: Other; Pulmotech: Other; Liberum: Consultancy; Jazz: Consultancy; Genentech: Consultancy, Other: Grant/research support; Dalichi Sankyo: Consultancy; Cure: Speakers Bureau; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; Aglos: Consultancy; AbbVie: Consultancy, Other: Grant/research support.

Background: The outcomes in pts with newly diagnosed (ND) FLT3 mutated (m) AML ineligible for intensive chemotherapy (IC) and R/R FLT3 AML are poor. Quiz, a potent FLT3i, demonstrated synergy with VEN in AML cell lines and PDX models (Mali Haematologica 2020). We evaluated the Quiz, VEN, and DAC triple combination in pts with R/R or ND FLT3m AML. Methods: The ND cohort included pts ineligible for IC, and R/R cohort included pts with ≤ 5 prior treatments for AML (i.e. up to salvage 5). Pts had ECOG PS ≤2, adequate organ function, and QTcF 5% continued VEN for 21 days during cycle 1 (figure 1). Responses were per modified CRc criteria as used in the ADMIRAL and QUANTUM-R registration studies. Results: 31 pts were enrolled including 25 R/R and 6 ND (Table 1). Of 25 pts with R/R AML (median 3 [range 1-5] prior therapies), 80% had ≥1 prior FLT3i's (72% had prior gilteritinib), and 40% had prior ASCT. In this high-risk R/R Cohort, 2 pts were early to evaluate (still in the first cycle). CRc rate among remaining 23 pts was 65% (15/23) (including CR 13% and CRi 52%).MFC (sensitivity 10 -4) and FLT3-PCR (sensitivity 10 -2-10 -3) negativity rates among responders were 36% (5/14), and 42% (5/12), respectively. The median (med) number of cycles to response was 1 [range 1-2]. 30- and 60-day mortality rates were 4% (N=1) and 16% (N=4). With a med follow-up (f/u) of 7.1 months, the med OS was encouraging at 7.5 months and 1-year OS 34% in this predominantly gilteritinib (gilt) exposed, heavily pretreated R/R cohort. Although numbers were small, pts who received no prior gilt (n=7) had longer OS than pts who received prior gilt (n=18); 19.0 months vs. 7.1 months. In the ND cohort, 1 pt was not evaluable (switched therapy on Day 2 of Cycle 1). Of 5 evaluable ND AML, all achieved CRc (2 CR, 3 CRi) with 2/4 and 4/5 responders negative by FLT3-PCR and MFC, respectively. With a med f/u of 7 months the median OS was 14.5 months. No pts developed a dose-limiting toxicity (DLT) with 30 mg/day Quiz, however with the 40mg/day Quiz, the first 2 pts treated developed hematologic DLT (grade ≥3 neutropenia with a 5% included neutropenic fever (32%), pneumonia (32%), sepsis (11%), other infections (7%). No QTcF prolongations >480 msec were noted. 3/5 (60%) and 7/19 (37%) pts underwent ASCT in frontline and R/R cohorts, respectively. Of the 5 frontline pts at the last follow-up; 4 in CR and 1 died with relapsed AML at 14 months. Of 15 CRc pts in the R/R cohort, 8 are alive (7 CR, 1 relapse), and 7 died (6 relapsed, 1 died in CR). Baseline mutations in durable responders (>6m) vs. early relapse ( Conclusion: DAC + VEN + Quiz is active in heavily pretreated and prior FLT3i exposed (including 68% with prior gilteritinib) R/R FLT3-ITDm pts, with a CRc rate of 65% and a med OS of 7.5 months, 1-year OS 34%. Quiz 30mg QDay was established as the RP2D for the triplet. RAS/MAPK mutations continue to be associated with primary and secondary resistance even with this triplet. Accrual continues and updated clinical, NGS and mass cytometry data will be presented. Figure 1 Figure 1. Disclosures Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Kantarjian: BMS: Research Funding; Daiichi-Sankyo: Research Funding; Precision Biosciences: Honoraria; Astellas Health: Honoraria; Novartis: Honoraria, Research Funding; NOVA Research: Honoraria; Ascentage: Research Funding; Taiho Pharmaceutical Canada: Honoraria; Immunogen: Research Funding; KAHR Medical Ltd: Honoraria; Pfizer: Honoraria, Research Funding; Jazz: Research Funding; Ipsen Pharmaceuticals: Honoraria; Aptitude Health: Honoraria; AbbVie: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Astra Zeneca: Honoraria. DiNardo: Foghorn: Honoraria, Research Funding; Novartis: Honoraria; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Forma: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; ImmuneOnc: Honoraria, Research Funding; Agios/Servier: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Kadia: Genentech: Consultancy, Other: Grant/research support; Ascentage: Other; AstraZeneca: Other; Pfizer: Consultancy, Other; Pulmotech: Other; Cure: Speakers Bureau; Novartis: Consultancy; Liberum: Consultancy; Dalichi Sankyo: Consultancy; Sanofi-Aventis: Consultancy; Cellonkos: Other; Jazz: Consultancy; Amgen: Other: Grant/research support; Aglos: Consultancy; Genfleet: Other; Astellas: Other; BMS: Other: Grant/research support; AbbVie: Consultancy, Other: Grant/research support. Konopleva: Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; Calithera: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Stemline Therapeutics: Research Funding; Ablynx: Other: grant support, Research Funding; Cellectis: Other: grant support; Forty Seven: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Agios: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; AstraZeneca: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Sanofi: Other: grant support, Research Funding; KisoJi: Research Funding; Ascentage: Other: grant support, Research Funding. Borthakur: University of Texas MD Anderson Cancer Center: Current Employment; Protagonist: Consultancy; Takeda: Membership on an entity's Board of Directors or advisory committees; ArgenX: Membership on an entity's Board of Directors or advisory committees; Ryvu: Research Funding; GSK: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astex: Research Funding. Pemmaraju: ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; LFB Biotechnologies: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Samus: Other, Research Funding; Plexxicon: Other, Research Funding; Aptitude Health: Consultancy; Springer Science + Business Media: Other; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy; Blueprint Medicines: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Clearview Healthcare Partners: Consultancy; MustangBio: Consultancy, Other; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Daiichi Sankyo, Inc.: Other, Research Funding; Cellectis S.A. ADR: Other, Research Funding; Bristol-Myers Squibb Co.: Consultancy; Affymetrix: Consultancy, Research Funding; CareDx, Inc.: Consultancy; Roche Diagnostics: Consultancy; Sager Strong Foundation: Other; DAVA Oncology: Consultancy; Incyte: Consultancy; Protagonist Therapeutics, Inc.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Short: Jazz Pharmaceuticals: Consultancy; Novartis: Honoraria; NGMBio: Consultancy; Astellas: Research Funding; AstraZeneca: Consultancy; Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Alvarado: FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; BerGenBio: Research Funding; MEI Pharma: Research Funding; Astex Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; CytomX Therapeutics: Consultancy; Sun Pharma: Consultancy, Research Funding. Loghavi: Abbvie: Current equity holder in publicly-traded company; Curio Sciences: Honoraria; Gerson Lehrman Group: Consultancy; Guidepoint: Consultancy; Peerview: Honoraria; Qualworld: Consultancy. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Ravandi: Xencor: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Novartis: Honoraria; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Taiho: Honoraria, Research Funding; Prelude: Research Funding; Astex: Honoraria, Research Funding; AstraZeneca: Honoraria; Agios: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding. Andreeff: Novartis, Cancer UK; Leukemia & Lymphoma Society (LLS), German Research Council; NCI-RDCRN (Rare Disease Clin Network), CLL Foundation; Novartis: Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy; Daiichi-Sankyo: Consultancy, Research Funding; Breast Cancer Research Foundation: Research Funding; Karyopharm: Research Funding; ONO Pharmaceuticals: Research Funding; Medicxi: Consultancy; Amgen: Research Funding; Senti-Bio: Consultancy; Glycomimetics: Consultancy; AstraZeneca: Research Funding; Reata, Aptose, Eutropics, SentiBio; Chimerix, Oncolyze: Current holder of individual stocks in a privately-held company; Aptose: Consultancy; Oxford Biomedica UK: Research Funding. Daver: FATE Therapeutics: Research Funding; Sevier: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Hanmi: Research Funding; Novimmune: Research Funding; Glycomimetics: Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy; Genentech: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding.

Background: Older patients (pt) with acute myeloid leukemia (AML) and patients with high-risk myelodysplastic syndrome / chronic myelomonocytic leukemia (HR MDS/CMML) have poor outcomes. We showed that 10-day decitabine with venetoclax (DEC10-VEN) is a safe and effective strategy and offers potentially better outcomes compared to intensive chemotherapy in older pts with newly diagnosed (ND) AML, as well as relapsed or refractory (R/R) AML (DiNardo et al. Lancet Haematol 2020; Maiti et al. Am J Hematol 2021; Maiti et al. Cancer 2021). We here in present updated results of this prospective phase II trial (NCT03404193). Methods: Eligibility criteria included ECOG PS ≤3, WBC ≤10 x10 9/L, and adequate organ function. Decitabine dose was 20 mg/m 2 IV daily on D1-10 until CR/CRi, followed by 5-day cycles. Venetoclax was given on D1-28 in cycle 1 but was interrupted on C1D21 until count recovery if the D21 bone marrow (BM) had ≤5% blasts. Venetoclax dose was 400 mg PO daily or equivalent with concomitant azole antifungals as previously described (DiNardo et al. Lancet Haematol. 2020). Venetoclax duration could be reduced to 14 to 7 days in subsequent cycles in cases of prolonged myelosuppression. All pts received cytoreduction prior to start, tumor lysis syndrome (TLS) prophylaxis and antimicrobial prophylaxis. Concomitant FLT3 tyrosine kinase inhibitors were allowed in FLT3-mutated AML. Pts could proceed to allogeneic stem-cell transplantation (SCT) after response, if eligible. Primary objective was overall response rate and secondary objectives included safety and overall survival. Outcomes and endpoints were defined per ELN2017 criteria. Measurable residual disease (MRD) was assessed using multiparametric flow cytometry (sensitivity 0.1%) and reported for all responding pts with evaluable MRD sample. Results: Between January 2018 and April 2021 we enrolled 219 pts with ND AML (n=83), untreated sAML (n=20), treated sAML (n=25), R/R AML (n=71) and HR MDS/CMML (n=20). This high-risk cohort included 54% of pts ≥70 yrs (n=119), 57% pts were men, 29% pts had ECOG PS ≥2, and 57% pts had adverse-risk AML (Table 1). The 30 mortality was 1% for ND pts and 3.6% for all pts. There were 346 treatment-related adverse events in 181 patients including infections with grade 3/4 neutropenia (40%), febrile neutropenia (29%), and infection with unknown ANC (17%, Table 2). There were 11 grade 5 events including infections with grade 3/4 neutropenia (n=6), infections with unknown ANC (n=4), and renal failure (n=1). The CR/CRi rate in ND AML was 83%, in untreated sAML was 65%, in treated sAML was 40%, in R/R AML was 42% and in HR-MDS/CMML was 20% (Table 3). Rates of negative measurable residual disease (MRD) by flow cytometry (0.1%) in ND AML was 73%, in untreated sAML was 53%, in treated sAML was 65%, and in R/R AM was 58%. After a median follow-up of 24.7 months (mo), the median OS in ND AML was 16.2 mo, in untreated sAML was 10.7 mo, in treated sAML was 5.8 mo, in R/R AML was 7.8 mo, and in HR-MDS/CMML was 10.1 mo (Fig. 1a). The 1-yr OS in ND AML was 54%, in untreated sAML was 41%, in treated sAML was 36%, in R/R AML was 41%, and in HR MDS/CMML was 35%. Median RFS for pts with ND AML was 10.9 mo, in the untreated sAML was 6.7 mo, in treated sAML was 11.4 mo, and in R/R AML was 8.4 mo (Fig. 1b). 44 pts underwent SCT after achieving response including ND AML (n=17), untreated sAML (n=4), treated sAML (n=3), R/R AML (n=16), and HR-MDS/CMML (n=4). The 100-day post-SCT mortality was 9% (n=4). Median OS after SCT in pts with previously untreated AML was 31.1 mo and in previously treated AML was 15.0 mo (Fig. 1c) 199 pts (91%) have discontinued treatment and 69 pts (32%) are alive. The most common reasons for treatment discontinuation included refractory disease in 49 pts (22%), relapse in 45 pts (21%), SCT in 44 pts (20%). Conclusions: DEC10-VEN is an effective therapy for older pts with ND and R/R AML. Transition to SCT after response with DEC10-VEN may offer long-term survival advantage in this older/unfit population with both ND and R/R AML. The trial continues to accrue. Based on these findings we have initiated a phase II trial of 10-day oral decitabine (ASTX727) with venetoclax in R/R AML (NCT04975919). Figure 1 Figure 1. Disclosures DiNardo: GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria, Research Funding; Forma: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Agios/Servier: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; Novartis: Honoraria; Foghorn: Honoraria, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Pemmaraju: DAVA Oncology: Consultancy; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Cellectis S.A. ADR: Other, Research Funding; CareDx, Inc.: Consultancy; Springer Science + Business Media: Other; MustangBio: Consultancy, Other; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; LFB Biotechnologies: Consultancy; Daiichi Sankyo, Inc.: Other, Research Funding; Affymetrix: Consultancy, Research Funding; Roche Diagnostics: Consultancy; Samus: Other, Research Funding; Blueprint Medicines: Consultancy; Clearview Healthcare Partners: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Celgene Corporation: Consultancy; Incyte: Consultancy; Protagonist Therapeutics, Inc.: Consultancy; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Plexxicon: Other, Research Funding; Aptitude Health: Consultancy; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Daver: Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Trovagene: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Hanmi: Research Funding; Amgen: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Novimmune: Research Funding; Astellas: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Glycomimetics: Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Issa: Kura Oncology: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Syndax Pharmaceuticals: Research Funding. Borthakur: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy; ArgenX: Membership on an entity's Board of Directors or advisory committees; Ryvu: Research Funding; University of Texas MD Anderson Cancer Center: Current Employment; Astex: Research Funding; Protagonist: Consultancy. Ravandi: Astex: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Taiho: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Xencor: Honoraria, Research Funding; Agios: Honoraria, Research Funding; AstraZeneca: Honoraria; Prelude: Research Funding; Novartis: Honoraria; AbbVie: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz: Honoraria, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding. Alvarado: MEI Pharma: Research Funding; Astex Pharmaceuticals: Research Funding; FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; BerGenBio: Research Funding; CytomX Therapeutics: Consultancy; Sun Pharma: Consultancy, Research Funding. Kadia: AbbVie: Consultancy, Other: Grant/research support; Cure: Speakers Bureau; Genfleet: Other; Cellonkos: Other; Sanofi-Aventis: Consultancy; Liberum: Consultancy; Astellas: Other; AstraZeneca: Other; Jazz: Consultancy; Genentech: Consultancy, Other: Grant/research support; BMS: Other: Grant/research support; Dalichi Sankyo: Consultancy; Ascentage: Other; Pulmotech: Other; Novartis: Consultancy; Pfizer: Consultancy, Other; Aglos: Consultancy; Amgen: Other: Grant/research support. Short: Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria; Astellas: Research Funding; AstraZeneca: Consultancy; Jazz Pharmaceuticals: Consultancy; NGMBio: Consultancy; Novartis: Honoraria. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Jain: Bristol Myers Squibb: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; Pfizer: Research Funding; Servier: Honoraria, Research Funding; Janssen: Honoraria; Incyte: Research Funding; Adaptive Biotechnologies: Honoraria, Research Funding; Precision Biosciences: Honoraria, Research Funding; Aprea Therapeutics: Research Funding; Fate Therapeutics: Research Funding; Beigene: Honoraria; Cellectis: Honoraria, Research Funding; ADC Therapeutics: Honoraria, Research Funding; TG Therapeutics: Honoraria; Genentech: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Pharmacyclics: Research Funding. Wierda: Janssen: Research Funding; Karyopharm: Research Funding; Genentech: Research Funding; Xencor: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Acerta Pharma Inc.: Research Funding; AstraZeneca: Research Funding; Juno Therapeutics: Research Funding; Gilead Sciences: Research Funding; Cyclacel: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Miragen: Research Funding; Sunesis: Research Funding; GSK/Novartis: Research Funding; KITE Pharma: Research Funding; Loxo Oncology, Inc.: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding. Sasaki: Novartis: Consultancy, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees. Takahashi: Novartis: Consultancy; Celgene/BMS: Consultancy; GSK: Consultancy; Symbio Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Burger: AstraZeneca: Consultancy; Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau; Beigene: Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Verstovsek: CTI BioPharma: Research Funding; Ital Pharma: Research Funding; Incyte Corporation: Consultancy, Research Funding; Gilead: Research Funding; Genentech: Research Funding; PharmaEssentia: Research Funding; Promedior: Research Funding; Protagonist Therapeutics: Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Blueprint Medicines Corp: Research Funding; Celgene: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; AstraZeneca: Research Funding; Novartis: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy. Andreeff: Glycomimetics: Consultancy; Aptose: Consultancy; AstraZeneca: Research Funding; Oxford Biomedica UK: Research Funding; Amgen: Research Funding; Syndax: Consultancy; Medicxi: Consultancy; Novartis, Cancer UK; Leukemia & Lymphoma Society (LLS), German Research Council; NCI-RDCRN (Rare Disease Clin Network), CLL Foundation; Novartis: Membership on an entity's Board of Directors or advisory committees; Breast Cancer Research Foundation: Research Funding; Reata, Aptose, Eutropics, SentiBio; Chimerix, Oncolyze: Current holder of individual stocks in a privately-held company; ONO Pharmaceuticals: Research Funding; Karyopharm: Research Funding; Daiichi-Sankyo: Consultancy, Research Funding; Senti-Bio: Consultancy. Bose: Pfizer: Research Funding; Constellation Pharmaceuticals: Research Funding; Novartis: Honoraria; Sierra Oncology: Honoraria; Kartos Therapeutics: Honoraria, Research Funding; Blueprint Medicines: Honoraria, Research Funding; CTI BioPharma: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Incyte Corporation: Honoraria, Research Funding; Astellas: Research Funding; NS Pharma: Research Funding; Promedior: Research Funding. Ferrajoli: AstraZeneca: Other: Advisory Board, Research Funding; BeiGene: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board . Thompson: Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Janssen: Consultancy, Honoraria; Gilead: Other: Institution: Advisory/Consultancy, Honoraria; AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Amgen: Other: Institution: Honoraria, Research Grant/Funding. Kantarjian: AbbVie: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Immunogen: Research Funding; BMS: Research Funding; Jazz: Research Funding; Ascentage: Research Funding; Daiichi-Sankyo: Research Funding; Ipsen Pharmaceuticals: Honoraria; Astra Zeneca: Honoraria; KAHR Medical Ltd: Honoraria; Aptitude Health: Honoraria; Pfizer: Honoraria, Research Funding; Astellas Health: Honoraria; Novartis: Honoraria, Research Funding; NOVA Research: Honoraria; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. Konopleva: Agios: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; KisoJi: Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Cellectis: Other: grant support; Ascentage: Other: grant support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; Stemline Therapeutics: Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support.

Background: MDS is a clonal hematological disorder characterized by bone marrow dysplasia, ineffective hematopoiesis, and an increased risk of transformation to acute myeloid leukemia (AML). For the majority of high-risk MDS patients who are not eligible for curative allogeneic hematopoietic stem cell transplantation (aHSCT), hypomethylating agents (HMAs) such as 5-azacytidine (AZA) represent the standard of care. However, overall response rates (ORRs) with AZA monotherapy remain relatively low (28-48%) and the length of response is limited (median 8-10m). In patients who fail or relapse after HMA therapy, prognosis is dismal and therapeutic options are limited. Pre-clinical data suggest BCL-2 inhibitors such as Venetoclax (VEN) are synergistic with HMAs in MDS. We designed this phase I/II study (NCT04160052) to evaluate the safety, tolerability, and response rate of the AZA-VEN combination for the treatment of high-risk MDS and chronic myelomonocytic leukemia (CMML). Methods: Patients ≥ 18 years of age were eligible for enrollment if they were diagnosed with HMA-naïve high-risk MDS (IPSS Int-2/High), relapsed/refractory MDS after at least 4 cycles of HMA therapy, or CMML. Bone marrow (BM) blast count > 5% was required. Patients with prior BCL-2 inhibitor exposure and low risk MDS (IPSS Low/Int-1) were excluded. AZA 75 mg/m 2 IV/SC on days 1-5 and escalating doses (3+3 algorithm) of VEN PO on days 1-7 or 1-14 were administered every 28 days. VEN dosage was adjusted for concomitant CYP3A inhibitor use. The primary objective is safety and tolerability (phase I) and ORR (phase II). The incidence and severity of adverse events (AEs) were evaluated using CTCAE v 5.0. ORR was defined as the proportion of patients who achieved complete remission (CR), partial remission (PR), marrow CR (mCR), or hematological improvement (HI) lasting at least 4 weeks (Modified IWG Response Criteria for MDS, Cheson 2006). Overall survival (OS) and progression-free survival (PFS) were assessed as secondary objectives. Results: As of July 31 st 2021, 17 patients (median age 68, range 58-84) have been enrolled in the phase I portion of the study (8 HMA-naïve MDS, 4 MDS after HMA failure, and 5 CMML). The median BM blast count was 11% (6-19%). 13 patients (76%) were Int-2 and 4 patients (24%) were High risk by IPSS. Good, intermediate, and poor risk cytogenetics were observed in 6 (35%), 4 (24%), and 7 (41%) patients, respectively. 6 patients (35%) had complex karyotypes and 5 (29%) had TP53 mutations. Of the 7 previously treated patients, the median number of prior therapies was 1 (1-5). The median number of cycles of AZA-VEN completed on study at the time of data cutoff was 3 (0-10) and the median follow-up was 11.6m. VEN dose ranged from 20 to 400 mg daily. 5 (29%) patients went off study for aHSCT but continued to be followed for the survival analysis. The most common grade 3/4 AEs were thrombocytopenia (35%), lung infections (29%), and neutropenia (24%). 2 grade 5 AEs (sepsis) occurred on study, one in a patient whose best response was SD after 5 cycles and one in a patient who had completed only 2 days of cycle 1. 30-day mortality was 6%. 15 patients were evaluable for response because they had completed at least 1 cycle of the study drugs. The ORR was 93% (1 CR, 9 mCR, 4 mCR with HI). In responders, the median number of cycles to response was 1 (range 1-2) and median duration of response 6.3m. No patient responded beyond cycle 2. Median PFS and OS for the evaluable cohort were 8.4m and 13m, respectively. Transformation to AML occurred in 3 patients (20%). Of the 4 survivors beyond 10m, 3 (75%) have undergone consolidative aHSCT. Conclusions: AZA-VEN was a tolerable and effective treatment strategy in this high-risk group of patients. Notably, a very high ORR was observed in this phase I study. Responses were rapid compared to historical data with AZA alone. AZA-VEN was an effective bridge to aHSCT. Recruitment is ongoing to determine the MTD/RP2D. Figure 1 Figure 1. Disclosures Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Kantarjian: Novartis: Honoraria, Research Funding; Astra Zeneca: Honoraria; Amgen: Honoraria, Research Funding; Ipsen Pharmaceuticals: Honoraria; BMS: Research Funding; Daiichi-Sankyo: Research Funding; Jazz: Research Funding; Pfizer: Honoraria, Research Funding; Aptitude Health: Honoraria; Ascentage: Research Funding; AbbVie: Honoraria, Research Funding; Immunogen: Research Funding; NOVA Research: Honoraria; KAHR Medical Ltd: Honoraria; Astellas Health: Honoraria; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. DiNardo: Agios/Servier: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Takeda: Honoraria; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Research Funding; ImmuneOnc: Honoraria, Research Funding; Forma: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Foghorn: Honoraria, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Daver: Astellas: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Hanmi: Research Funding; Trillium: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Sevier: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy; Glycomimetics: Research Funding; Novimmune: Research Funding; Genentech: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Kadia: Sanofi-Aventis: Consultancy; Cellonkos: Other; Ascentage: Other; Novartis: Consultancy; Liberum: Consultancy; Genfleet: Other; Astellas: Other; AstraZeneca: Other; Jazz: Consultancy; Pulmotech: Other; Pfizer: Consultancy, Other; Aglos: Consultancy; Genentech: Consultancy, Other: Grant/research support; Dalichi Sankyo: Consultancy; Cure: Speakers Bureau; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; AbbVie: Consultancy, Other: Grant/research support. Takahashi: Celgene/BMS: Consultancy; Symbio Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; GSK: Consultancy. Short: Takeda Oncology: Consultancy, Research Funding; Astellas: Research Funding; Novartis: Honoraria; NGMBio: Consultancy; Jazz Pharmaceuticals: Consultancy; AstraZeneca: Consultancy; Amgen: Consultancy, Honoraria. Alvarado: Sun Pharma: Consultancy, Research Funding; Jazz Pharmaceuticals: Research Funding; BerGenBio: Research Funding; CytomX Therapeutics: Consultancy; Astex Pharmaceuticals: Research Funding; MEI Pharma: Research Funding; Daiichi-Sankyo: Research Funding; FibroGen: Research Funding. Thompson: Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Amgen: Other: Institution: Honoraria, Research Grant/Funding; Janssen: Consultancy, Honoraria; Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Gilead: Other: Institution: Advisory/Consultancy, Honoraria. Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Ravandi: Astex: Honoraria, Research Funding; Prelude: Research Funding; Taiho: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Novartis: Honoraria; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding; Xencor: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Pemmaraju: Plexxicon: Other, Research Funding; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Roche Diagnostics: Consultancy; MustangBio: Consultancy, Other; Aptitude Health: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Samus: Other, Research Funding; DAVA Oncology: Consultancy; CareDx, Inc.: Consultancy; Springer Science + Business Media: Other; Cellectis S.A. ADR: Other, Research Funding; Daiichi Sankyo, Inc.: Other, Research Funding; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; LFB Biotechnologies: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Incyte: Consultancy; Affymetrix: Consultancy, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Clearview Healthcare Partners: Consultancy; Blueprint Medicines: Consultancy; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. OffLabel Disclosure: Venetoclax is not currently approved for MDS but has promising pre-clinical activity data.

Introduction When added to cytarabine (Ara-c) or hypomethylating agents (HMA), the BCL2 inhibitor, venetoclax (VTX), has been reported to improve response and overall survival (OS) rates. However, resistance and relapse still occur in the majority, and, although alterations in MCL1 and BCLXL are noted at relapse, identification of prognostic features remain unknown, notably not correlating with expression of the BCL2 target. Identification of prognostic markers could guide VTX use in patients and/or post-remission therapy. We searched for protein expression targets individually and collectively to predict VTX response and relapse in AML. Methods Reverse Phase Protein Array (RPPA) was performed on diagnostic leukemia samples of 818 adults with AML, of which 143 received VTX including 33 in combination with high dose Ara-C, 5 with standard dose Ara-C, 50 with HMA, and 13 with HMA and targeted therapy. Protein expression levels were evaluated using 390 validated antibodies were analyzed in the context of clinical data compiled by retrospective chart review. Pearson correlation was used to identify significant protein-protein correlations. Survival curves were generated by the Kaplan-Meier method and survival data was analyzed by multivariate cox regression model. Protein expression signatures were identified by hierarchical clustering and predictive models of classifiers were determined by classification and regression trees (CART) analysis. Results We queried the 390 proteins assayed in the 143 VTX treated patients to identify proteins individually prognostic (p Discussion Protein expression patterns, individually and in combination, were very highly predictive of outcome to VTX containing combination chemotherapy. A group with lower response rates, higher relapse rates, shorter RD and inferior OS was defined. A kit to prospectively determine cluster membership is in development. If validated this could be used to triage high-risk patients to alternate therapies, such as transplant, in CR1. Many new targets for combination therapy to prevent VTX resistance were identified and need to be tested in the laboratory for clinical relevance. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: Blinatumomab is highly effective therapy for both the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (ALL) and persistent or recurrent measurable residual disease (MRD) after initial ALL therapy. We hypothesized that early incorporation of blinatumomab in patients (pts) with newly diagnosed Philadelphia chromosome (Ph)-negative B-cell ALL would lead to deeper and more durable responses, reduce relapses, and improve survival. Methods: Pts 14-59 years of age with newly diagnosed Ph-negative pre-B-cell ALL, including pts who had received no more than 1 prior cycle of chemotherapy, were eligible. Pts were required to have a performance status of ≤3, total bilirubin ≤2 mg/dl, creatinine ≤2 mg/dl, and no significant CNS pathology (with the exception of CNS leukemia). Pts received hyper-CVAD alternating with high-dose methotrexate and cytarabine for up to 4 cycles, followed by 4 cycles of blinatumomab at standard doses. Pts with CD20+ disease (≥1% cells) received 8 doses of ofatumumab (2000 mg) or rituximab (375 mg/m 2). Eight administrations of prophylactic IT chemotherapy were given in the first 4 cycles. Maintenance was with alternating blocks of POMP (given in maintenance cycles 1-3, 5-7, 9-11, and 13-15) and blinatumomab (given in maintenance cycles 4, 8, and 12). Beginning with pt #10, those with high-risk disease features (e.g. CRLF2+ by flow cytometry, complex karyotype, KMT2A rearranged, low-hypodiploidy/near triploidy, TP53 mutation, or persistent MRD) started blinatumomab after 2 cycles of hyper-CVAD. Results: 38 evaluable pts have been treated. 6 pts were in complete remission (CR) at enrollment and unevaluable for morphologic response. Pt characteristics of the 38 evaluable pts are summarized in Table 1. Median age was 37 years (range, 17-59 years). At least one high-risk feature was present in 21 pts (55%), including TP53 mutation in 27%, CRLF2+ in 19%, and an adverse-risk karyotype in 32%. 84% of pts received ofatumumab or rituximab. Among 32 pts with active disease at study entry, 100% achieved CR, with 81% achieving CR after the first cycle (Table 1). MRD negativity by 6-color flow cytometry was achieved in 22/26 responding pts (85%) after 1 cycle and 37/38 pts (97%) overall. The 60-day mortality rate was 0%. With a median follow-up of 27 months (range, 11-55 months), the 3-year continuous remission and OS rates were 80% and 83%, respectively (Figure 1). Overall, 5 pts (13%) relapsed, 13 (34%) underwent allogeneic SCT in first remission (including 2 additional pts who relapsed post-SCT), 1 died in CR (possible pulmonary embolism), and 19 (50%) remain in continuous remission and are currently on treatment or have completed maintenance. All relapses occurred in pts with established poor-risk features and no relapses have occurred beyond 2 years from the start of treatment. OS with hyper-CVAD plus blinatumomab compares favorably to a historical cohort of pts treated with hyper-CVAD plus ofatumumab (3-year OS 83% versus 66%, respectively; P=0.2). Treatment was overall well-tolerated. Four pts developed grade 2-3 cytokine release syndrome (grade 2, n=3; grade 3, n=1) which resolved with corticosteroids and interruption of blinatumomab. Overall, 16 (42%) pts had a neurological adverse event of any grade due to blinatumomab. Four pts (11%) developed grade 3 neurologic toxicity related to blinatumomab, all of which was transient and reversible. Only one pt discontinued blinatumomab due to blinatumomab-related adverse event (grade 2 encephalopathy and dysphasia). Conclusion: Hyper-CVAD with sequential blinatumomab is highly effective as frontline treatment of Ph-negative B-cell ALL, with an overall MRD negativity rate of 97% and a 3-year OS rate of 83%. This study shows the potential benefit of incorporating frontline blinatumomab into the treatment of younger adults with ALL and also shows that reduction of chemotherapy in this context is feasible. Figure 1 Figure 1. Disclosures Short: Novartis: Honoraria; AstraZeneca: Consultancy; Astellas: Research Funding; Jazz Pharmaceuticals: Consultancy; NGMBio: Consultancy; Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Kantarjian: Precision Biosciences: Honoraria; Immunogen: Research Funding; Jazz: Research Funding; Astra Zeneca: Honoraria; KAHR Medical Ltd: Honoraria; Novartis: Honoraria, Research Funding; Aptitude Health: Honoraria; Daiichi-Sankyo: Research Funding; Amgen: Honoraria, Research Funding; Ipsen Pharmaceuticals: Honoraria; Astellas Health: Honoraria; Ascentage: Research Funding; AbbVie: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; NOVA Research: Honoraria; BMS: Research Funding; Taiho Pharmaceutical Canada: Honoraria. Ravandi: Taiho: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Prelude: Research Funding; Xencor: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Research Funding; AstraZeneca: Honoraria; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding; Agios: Honoraria, Research Funding; Novartis: Honoraria; AbbVie: Honoraria, Research Funding. Thompson: Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Gilead: Other: Institution: Advisory/Consultancy, Honoraria; AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; Janssen: Consultancy, Honoraria; Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Amgen: Other: Institution: Honoraria, Research Grant/Funding. Ferrajoli: BeiGene: Other: Advisory Board, Research Funding; AstraZeneca: Other: Advisory Board, Research Funding; Janssen: Other: Advisory Board . Kadia: Astellas: Other; Genentech: Consultancy, Other: Grant/research support; Sanofi-Aventis: Consultancy; Cellonkos: Other; Pfizer: Consultancy, Other; Pulmotech: Other; Amgen: Other: Grant/research support; Cure: Speakers Bureau; Novartis: Consultancy; BMS: Other: Grant/research support; AstraZeneca: Other; Liberum: Consultancy; Ascentage: Other; Genfleet: Other; Jazz: Consultancy; Dalichi Sankyo: Consultancy; Aglos: Consultancy; AbbVie: Consultancy, Other: Grant/research support. Jain: Janssen: Honoraria; Precision Biosciences: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Adaptive Biotechnologies: Honoraria, Research Funding; Incyte: Research Funding; Servier: Honoraria, Research Funding; Beigene: Honoraria; Cellectis: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; ADC Therapeutics: Honoraria, Research Funding; Aprea Therapeutics: Research Funding; TG Therapeutics: Honoraria; Pfizer: Research Funding; Fate Therapeutics: Research Funding; Genentech: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Pharmacyclics: Research Funding. Alvarado: Sun Pharma: Consultancy, Research Funding; Astex Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; CytomX Therapeutics: Consultancy; FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; BerGenBio: Research Funding; MEI Pharma: Research Funding. Yilmaz: Daiichi-Sankyo: Research Funding; Pfizer: Research Funding. Khoury: Stemline Therapeutics: Research Funding; Angle: Research Funding; Kiromic: Research Funding. Wang: Stemline Therapeutics: Honoraria. Konopleva: KisoJi: Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Cellectis: Other: grant support; Calithera: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Stemline Therapeutics: Research Funding; Sanofi: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Forty Seven: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Ablynx: Other: grant support, Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; AstraZeneca: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding. Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. OffLabel Disclosure: Blinatumomab in the frontline setting for B-cell ALL

Acute lymphoblastic leukemia (ALL) is the most common malignancy in pediatric patients spanning both B- and T-cell lineages. ALL also occurs less commonly in adults but with cure rates of only around 30%. Past work has characterized ALL into molecular subtypes spanning a range of aberrant chromosomal rearrangements and oncogene chimeric fusions driving malignancy. While transcriptional profiling of these subtypes has been extensively examined, the accompanying chromatin accessibility landscape and corresponding gene regulatory repertoire is not well characterized for many subtypes. To better profile the ALL epigenomic and gene regulatory repertoire we examined chromatin accessibility of 12 distinct molecular subtypes (BCR-ABL1, ETV6-RUNX1, Hyperdiploid, Hypodiploid, KMT2A rearranged, Ph-Like, PAX5, DUX4/ERG, TCF3-PBX1, T-ALL, Early T Precursor and B-other) across 189 primary patient samples of pediatric ALL (n = 106) and adult ALL (n = 83) origin using ATAC-seq. To our knowledge, this represents the largest collection of chromatin accessibility data in primary ALL samples spanning multiple molecular subtypes to date. Collectively, we identified over 600,000 accessible chromatin sites in the ALL genome with over 50,000 regions of differentially accessible chromatin encompassing both common and subtype-specific modalities. Further, transcription factor (TF) footprint profiling of ATAC-seq yielded tens of thousands of candidate TF binding events and identified key TF drivers within distinct molecular subtypes. We additionally performed H3K27ac ChIP-seq in a subset of 12 primary ALL patient samples, with integration of these histone data for select patient samples allowing inferences about candidate super-enhancer drivers of ALL molecular subtypes. Overall, these analyses and data offer a window into the gene regulatory and epigenetic landscape of ALL, and further highlight the complexity and heterogeneity of accessible chromatin landscapes among distinct molecular subtypes of ALL. Disclosures Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Pui: Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Data Monitoring Committee. Evans: Princess Máxima Center for Pediatric Oncology, Scientific Advisory Board, Chair: Membership on an entity's Board of Directors or advisory committees; St. Jude Children's Research Hospital, Emeritus Member (began Jan 2021): Ended employment in the past 24 months; BioSkryb, Inc.: Membership on an entity's Board of Directors or advisory committees.

The availability of targeted therapy and improved molecular characterization of Chronic Lymphocytic Leukemia (CLL) require a re-evaluation of treatment paradigms. As CLL heterogeneity is dependent on molecular and environmental factors, there is a need to create a new classification based on the integration of several factors. Here, we accomplish this goal by identifying CLL signatures using Reverse Phase Protein Array. Protein expression for 384 total and post translationally modified proteins was assessed in 871 CLL and Mature Small B Cell Leukemia (MSBL: HCL, HCLV, LGL-T, MCL, MZL, PLL, Richter's, T-Cell PLL) patients and was integrated with clinical data to identify strategies for improving diagnostics and therapy, making this the largest CLL proteomics study to date. Proteins were categorized into 40 protein functional groups (PFGs) based on literature and intra-dataset protein correlations and patients clustered based on PFG expression patterns into 6 recurrent protein expression signatures (PES) (Figure 1A). Individual protein expression (58/384 proteins), PFG expression (32/40) and overall PES were all highly prognostic of survival (OS) and time to first or second treatment (TTFT, TTST) (Figures 1B-C). The adhesion, apoptosis-occurring, apoptosis-regulating, heat shock, histone1 (marks), histone 2 (modifiers) and the STP-regulation PFGs were prognostic for all 3 outcome measures. Notably SG-A contained most of the MSBL and 15/16 cases of hairy cell leukemia, but the CLL cases within this SG fared very poorly. For OS, groups A and C had markedly inferior survival (P Figure 1 Figure 1. Disclosures Ferrajoli: Janssen: Other: Advisory Board ; AstraZeneca: Other: Advisory Board, Research Funding; BeiGene: Other: Advisory Board, Research Funding. Thompson: Genentech: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Amgen: Other: Institution: Honoraria, Research Grant/Funding; Adaptive Biotechnologies: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding, Expert Testimony; Pharmacyclics: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding; Janssen: Consultancy, Honoraria; Gilead: Other: Institution: Advisory/Consultancy, Honoraria; AbbVie: Other: Institution: Advisory/Consultancy, Honoraria, Research Grant/Funding. Burger: Pharmacyclics LLC: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Beigene: Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Gilead: Consultancy, Other: Travel/Accommodations/Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel/Accommodations/Expenses, Speakers Bureau; AstraZeneca: Consultancy; Janssen: Consultancy, Other: Travel/Accommodations/Expenses, Speakers Bureau. Wierda: Xencor: Research Funding; Karyopharm: Research Funding; Gilead Sciences: Research Funding; Acerta Pharma Inc.: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; AstraZeneca: Research Funding; Juno Therapeutics: Research Funding; KITE Pharma: Research Funding; Sunesis: Research Funding; Miragen: Research Funding; Oncternal Therapeutics, Inc.: Research Funding; Cyclacel: Research Funding; Loxo Oncology, Inc.: Research Funding; Janssen: Research Funding; Genentech: Research Funding; GSK/Novartis: Research Funding; Genzyme Corporation: Consultancy; AbbVie: Research Funding.

To the editor: Pure erythroid leukemia[1][1] (PEL), or AML-M6b, is a rare form of leukemia characterized by proliferation of >80% undifferentiated or pronormoblastic immature cells committed exclusively to the erythroid lineage.[2][2] Previous reports have described the aggressive nature of

Background Anemia is common in patients (pts) with myeloproliferative neoplasm (MPN)-associated myelofibrosis (MF). Furthermore, anemia is an on-target effect of therapeutic Janus kinase 2 (JAK2) inhibition, and may be the most frequent cause of ruxolitinib (rux) discontinuation (d/c) in clinical practice (Kuykendall, Ann Hematol 2018). Current therapies for anemia of MF (erythropoietin and analogs, danazol, IMiDs®) are unsatisfactory. Sotatercept (ACE-011) is a first-in-class, activin receptor type IIA ligand trap that may improve anemia by sequestering stromal transforming growth factor beta superfamily ligands that suppress terminal erythropoiesis (Iancu-Rubin, Exp Hematol 2013). Methods This is a phase 2, investigator-initiated, open-label, single institution study of sotatercept, administered subcutaneously every 3 weeks, in 2 cohorts of anemic pts (Hgb Results A total of 53 pts have been treated; one pt received only 0.3 mg/kg of sotatercept and is not considered further. Thirty one pts received sotatercept alone and 21 in combination with rux. Baseline characteristics appear in Table 1, panel A. Sixteen TD and 15 non-TD pts received sotatercept alone for a median of 5 (1-67) cycles. Thirteen pts received 0.75 mg/kg and 18, 1 mg/kg. Seven of 24 (29%) evaluable pts responded. Of these, 4 were anemia responses; 3 TD pts achieved TI. Five responses occurred at the 0.75 mg/kg dose, and 2 at the 1 mg/kg dose. Median time to response (TTR) was 21 (1-22) days and median duration of response (DOR) 13 (3.9-56.4) months. Seven pts (22.6%) received The combination cohort comprised 15 non-TD pts and 6 TD pts. The median number of cycles was 8 (2-43). Five of 17 (29%) evaluable pts in the combination cohort responded, all non-TD pts. Median TTR was 14 (7-147) days and median DOR 34.6 (3.1-47.9) months. Four pts (19%) received Several non-response-evaluable pts in both cohorts achieved ≥1.5 g/dl increments in Hgb from baseline that were not sustained for ≥12 wks because of early d/c of sotatercept. An additional pt in the combination cohort required a rux dose increase, leading to failure to sustain a ≥1.5 g/dl Hgb improvement. Across both cohorts, several responding pts required multiple protocol-specified drug holidays because of Hgb levels ≥11.5 g/dl, with resumption of sotatercept once Hgb was Sotatercept was well-tolerated (Table 1, panel B). Grade 3 adverse events possibly related to sotatercept were HTN (n=7), limb (bone/muscle/joint) pain (n=3) and headache (1). Conclusions Sotatercept is safe and effective against anemia of MPN-associated MF, both in non-TD and TD pts, with a response rate of 29% both when used alone and in conjunction with a stable dose of rux. A total of 60 pts are planned to be treated on this trial (NCT01712308). Disclosures Bose: Blueprint Medicines Corporation: Honoraria, Research Funding; NS Pharma: Research Funding; Constellation Pharmaceuticals: Research Funding; Astellas Pharmaceuticals: Research Funding; Pfizer, Inc.: Research Funding; Incyte Corporation: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene Corporation: Honoraria, Research Funding; CTI BioPharma: Honoraria, Research Funding; Promedior, Inc.: Research Funding; Kartos Therapeutics: Honoraria, Research Funding. Pemmaraju:Samus Therapeutics: Research Funding; AbbVie: Honoraria, Research Funding; MustangBio: Honoraria; SagerStrong Foundation: Other: Grant Support; Roche Diagnostics: Honoraria; Pacylex Pharmaceuticals: Consultancy; Plexxikon: Research Funding; Daiichi Sankyo: Research Funding; Stemline Therapeutics: Honoraria, Research Funding; Celgene: Honoraria; Incyte Corporation: Honoraria; Cellectis: Research Funding; Blueprint Medicines: Honoraria; Affymetrix: Other: Grant Support, Research Funding; Novartis: Honoraria, Research Funding; LFB Biotechnologies: Honoraria; DAVA Oncology: Honoraria. Daver:Fate Therapeutics: Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Jabbour:BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding. Kadia:Astellas: Research Funding; Pulmotec: Research Funding; Incyte: Research Funding; Ascentage: Research Funding; JAZZ: Honoraria, Research Funding; Cyclacel: Research Funding; Amgen: Research Funding; Celgene: Research Funding; Cellenkos: Research Funding; Genentech: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria; Abbvie: Honoraria, Research Funding; Astra Zeneca: Research Funding. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Amgen: Research Funding; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees. Cortes:Bristol-Myers Squibb: Research Funding; Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Sun Pharma: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Telios: Research Funding; Astellas: Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Merus: Research Funding; Immunogen: Research Funding; Novartis: Consultancy, Research Funding. Jain:BMS: Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aprea Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Fate Therapeutics: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding. Borthakur:Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; PTC Therapeutics: Research Funding; Jannsen: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Incyte: Research Funding; Polaris: Research Funding; Xbiotech USA: Research Funding; Oncoceutics: Research Funding; Curio Science LLC: Consultancy; FTC Therapeutics: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; BioTherix: Consultancy; Cyclacel: Research Funding; GSK: Research Funding; BioLine Rx: Research Funding; BMS: Research Funding; AstraZeneca: Research Funding. Alvarado:Sun Pharma: Research Funding; Astex Pharmaceuticals: Research Funding; MEI Pharma: Research Funding; Daiichi-Sankyo: Research Funding; Tolero Pharmaceuticals: Research Funding; FibroGen: Research Funding; Jazz Pharmaceuticals: Research Funding; BerGenBio ASA: Research Funding. Huynh-Lu:Incyte Corporation: Speakers Bureau. Nguyen-Cao:Incyte Corporation: Speakers Bureau. Garcia-Manero:Acceleron Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Novartis: Research Funding; Onconova: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Merck: Research Funding; AbbVie: Honoraria, Research Funding; H3 Biomedicine: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amphivena Therapeutics: Research Funding. Kantarjian:Oxford Biomedical: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Delta Fly: Honoraria; Janssen: Honoraria; Ascentage: Research Funding; BioAscend: Honoraria; Amgen: Honoraria, Research Funding; Aptitute Health: Honoraria; Immunogen: Research Funding; Jazz: Research Funding; Novartis: Honoraria, Research Funding; Sanofi: Research Funding; Pfizer: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; BMS: Research Funding; Adaptive biotechnologies: Honoraria; Abbvie: Honoraria, Research Funding. Verstovsek:Sierra Oncology: Consultancy, Research Funding; Gilead: Research Funding; Celgene: Consultancy, Research Funding; CTI Biopharma Corp: Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Promedior: Research Funding; Novartis: Consultancy, Research Funding; AstraZeneca: Research Funding; ItalPharma: Research Funding; Protagonist Therapeutics: Research Funding; PharmaEssentia: Research Funding; Incyte Corporation: Consultancy, Research Funding; Blueprint Medicines Corp: Research Funding; Genentech: Research Funding.

Background: Malignant cells exploit cellular metabolism for their survival through various mechanisms. A significant dependency of malignant myeloid cells on glutamine metabolism has been demonstrated in vitro. Glutamine can be metabolized by glutaminase to form glutamate, a precursor for the citric acid cycle. CB-839 is an oral allosteric inhibitor of glutaminase that has been shown to reduce the level of glutamate in AML cells, with a consequent decrease in oxidative phosphorylation and survival. We report an updated interim analysis of a phase Ib/II clinical study evaluating the safety and efficacy of CB-839 in combination with azacitidine for the treatment of patients with MDS. Methods: This is a single arm phase Ib/II trial of CB-839 in combination with azacitidine (AZA) for patients with intermediate and high-risk MDS. Eligibility includes adult patients with high-risk MDS (IPSS Int-2 or high risk) or Int-1 risk MDS with high-risk mutations in TP53, ASXL1, EZH2, or RUNX1. Patients with prior hypomethylating agent (HMA) treatment were eligible. The primary outcome for the phase Ib portion was to identify the safety and recommended phase II dose of CB-839 in combination with AZA, confirmed as 600mg bid continuously with standard 7-day AZA dosing. The primary outcome for the phase II portion is clinical efficacy using IWG response criteria. Secondary endpoints include evaluation of pharmacokinetics (PK), drug exposure levels, and overall survival. Results: 23 patients with MDS were enrolled between December 2017 and June 2020. Baseline characteristics are listed in Table 1. The median age was 71 (range, 49-83). 7 patients had prior HMA exposure (median 6 prior cycles, range 4-9), and 1 patient was previously treated with a non-HMA regimen. 8 patients (34.7%) had therapy-related MDS. 9 patients (39.1%) had complex cytogenetics. The most frequent mutations were ASXL1 (43.5%), TET2 (43.5%), TP53 (34.8%), and RUNX1 (30.4%). The most common drug-related non-hematologic adverse events (AEs) of any grade were nausea (52.2%), constipation (39.1%), fatigue (26.1%), anorexia (17.4%), and generalized weakness (17.4%). The most common therapy-related grade >3 AEs were transaminitis (13%), thrombocytopenia (26%), and neutropenia (30.4%). Five patients (21.7%) required dose reduction(s) of CB-839, with reductions due to transaminitis (n=2), myelosuppression (n=2), weakness (n=2), nausea (n=1), and fatigue (n=1). 30 and 60 day mortality were 0% and 4.3%, respectively. Best responses are detailed in Table 2. Objective response was defined as CR, morphologic CR (mCR), or hematologic improvement (HI), and was achieved in 15 out of 23 (65.2%) patients, including 5 CR and 10 mCR with or without HI. CR/mCR/HI rate was 62.5% (5/8) in previously-treated patients. Median number of cycles received was 4 (range, 1-17). 5 patients proceeded to allogeneic stem cell transplant. At median follow-up of 10.3 months (range, 1.0-28.5), 6 patients remain on study. Median OS (mOS) has not been reached; 1 year overall survival is 53.1% (Figure 1). Patients with TP53 mutations had CR/mCR rate of 62.5% (5/8) and mOS of 8 months. Patients with complex cytogenetics had CR/mCR rate of 66.7% (6/9) and mOS of 10.1 months. Bone marrow samples from a subset of patients were analyzed by multiparameter flow cytometry to fractionate phenotypically defined malignant leukemic stem cells (LSCs) as well as blast populations. We isolated hematopoietic stem and progenitor cells (HSPC, Lin−CD34+CD38−) expressing at least one LSC marker (CD45RA, CD123, or IL1RAP). At the same time, we isolated HSPCs that were triple-negative for CD45RA, CD123, and IL1RAP to enrich for pre-malignant stem cells. Analysis of representative samples showed a reduction in LSCs after treatment. We also observed an increase in progenitor cells (Lin-CD34+CD38+), showing increased differentiation after CB-839 treatment. This pattern was seen in 5 responders examined. We did not observe a reduction in LSCs in patients that did not respond clinically. Conclusions: CB-839 in combination with AZA is a safe and effective regimen for patients with advanced MDS. Encouraging responses were seen in previously-treated and genomically high-risk patients. Of interest, CB-839 demonstrated in vivo activity against LSCs, with an increase in myeloid progenitor cells consistent with myeloid differentiation in responding patients. The trial continues to accrue. (NCT03047993) Disclosures Konopleva: Agios: Research Funding; Ablynx: Research Funding; Calithera: Research Funding; Cellectis: Research Funding; Eli Lilly: Research Funding; Kisoji: Consultancy; Amgen: Consultancy; Forty-Seven: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Rafael Pharmaceutical: Research Funding; Ascentage: Research Funding; AstraZeneca: Research Funding; Sanofi: Research Funding. Borthakur:PTC Therapeutics: Consultancy; GSK: Research Funding; PTC Therapeutics: Research Funding; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; Abbvie: Research Funding; Jannsen: Research Funding; Oncoceutics: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Curio Science LLC: Consultancy; FTC Therapeutics: Consultancy; Xbiotech USA: Research Funding; Polaris: Research Funding; AstraZeneca: Research Funding; BioLine Rx: Consultancy; Cyclacel: Research Funding; Argenx: Consultancy; BioLine Rx: Research Funding; BMS: Research Funding. Jabbour:Adaptive Biotechnologies: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding. Pemmaraju:Stemline Therapeutics: Honoraria, Research Funding; Celgene: Honoraria; Pacylex Pharmaceuticals: Consultancy; Affymetrix: Other: Grant Support, Research Funding; Samus Therapeutics: Research Funding; Cellectis: Research Funding; DAVA Oncology: Honoraria; Plexxikon: Research Funding; Incyte Corporation: Honoraria; SagerStrong Foundation: Other: Grant Support; Daiichi Sankyo: Research Funding; MustangBio: Honoraria; AbbVie: Honoraria, Research Funding; Roche Diagnostics: Honoraria; Blueprint Medicines: Honoraria; Novartis: Honoraria, Research Funding; LFB Biotechnologies: Honoraria. Kadia:Novartis: Honoraria; Cyclacel: Research Funding; Pfizer: Honoraria, Research Funding; Cellenkos: Research Funding; Genentech: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Celgene: Research Funding; Incyte: Research Funding; Amgen: Research Funding; BMS: Honoraria, Research Funding; Astellas: Research Funding; Ascentage: Research Funding; Pulmotec: Research Funding; Astra Zeneca: Research Funding. Short:Takeda Oncology: Consultancy, Honoraria, Research Funding; Amgen: Honoraria; Astellas: Research Funding; AstraZeneca: Consultancy. Burger:AstraZeneca: Consultancy; Pharmacyclics, an AbbVie company: Consultancy, Research Funding, Speakers Bureau; Gilead Sciences: Consultancy, Research Funding; Janssen Pharmaceuticals: Consultancy, Speakers Bureau; Beigene: Research Funding, Speakers Bureau; TG Therapeutics: Research Funding, Speakers Bureau. Daver:Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding. Kantarjian:Abbvie: Honoraria, Research Funding; Delta Fly: Honoraria; Janssen: Honoraria; Oxford Biomedical: Honoraria; Ascentage: Research Funding; Sanofi: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Research Funding; BioAscend: Honoraria; Adaptive biotechnologies: Honoraria; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Jazz: Research Funding; Immunogen: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; BMS: Research Funding; Aptitute Health: Honoraria. Garcia-Manero:AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Amphivena Therapeutics: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; H3 Biomedicine: Research Funding; Jazz Pharmaceuticals: Consultancy; Merck: Research Funding; Novartis: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding. Verma:Medpacto: Research Funding; acceleron: Consultancy, Honoraria; Janssen: Research Funding; BMS: Consultancy, Research Funding; stelexis: Current equity holder in private company. DiNardo:Jazz: Honoraria; ImmuneOnc: Honoraria; Agios: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Syros: Honoraria; Novartis: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; MedImmune: Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Takeda: Honoraria; AbbVie: Consultancy, Honoraria, Research Funding. OffLabel Disclosure: CB-839, glutaminase inhibitor, investigation for use in advanced MDS

Background Unplanned 30-day readmissions are a frequent complication of acute leukemia therapy. However, there is limited data in acute lymphoblastic leukemia (ALL), with reported readmission rates (RaR) of 36% for pediatric ALL. Methods We retrospectively reviewed hospitalizations for ALL for adult patients >/= 18 years at our institution between January 2018 and December 2018. Unplanned readmissions were defined as any hospitalization within 30-days after discharge from the index admission, excluding all elective re-admissions for scheduled chemotherapy. Patients >/= 55 years of age receiving their initial induction therapy remained hospitalized for at least 21 days until bone marrow analysis and neutrophil count above 500/mm3. The primary objective was to identify the 30-day unplanned readmission rates, cause of readmissions, and predicted factors for readmissions. The secondary outcome included 30-day readmission mortality rate and inpatient mortality rate. Results There were a total of 841 ALL hospitalizations, 94 admissions for 63 pts (average 1.49 re-admit/pt) during frontline induction, 443 for 123 pts (average 3.6) during consolidation and 304 for 92 pts (average 3.3) with relapsed/refractory ALL (R/R ALL). The median age was 43 years for the frontline induction, 45 years for the consolidation group, and 42 years for R/R ALL patients. Baseline characteristics are listed in Table 1. The median length of index admission was 11 days for induction, 4 days during consolidation, and 8 days for R/R ALL. The 30-day unplanned RaR was 32% for induction, 28% for consolidation, and 36% for R/R ALL, with a median time to readmission of 6 days, 6 days, and 5 days, respectively. The most common causes of readmissions were infections (60%, 60% and 29% during induction, consolidation and R/R ALL respectively), including 30% neutropenic fever of unknown origin (NF), pain 20%, gastrointestinal infections 13%, neurologic causes (altered mental status, headache and LE weakness) 13%, and 10% bacteremia for induction; 19% neurologic causes, 17% NF, 15% upper respiratory infections, and11% pain during consolidation; and 9% bleeding, 8% NF, and 6% bacteremia for R/R ALL. (Figure 1) The median length of readmission was 5 days, 4 days, and 7 days for induction, consolidation, and R/R ALL patients, with a rate of ICU stay of 7%, 2%, and 18%, respectively. (Figure 2) While no significant differences were seen in the rate of ICU stay between readmissions and non-readmission for the induction and consolidation groups, R/R ALL patients had an increased incidence of ICU stay (18% vs. 11%, p=.001) and 30-day mortality (13% vs. 5% p=.010). We performed a logistical regression analysis to determine risk factors associated with readmissions. The multivariate analysis identified COPD (OR 3.30, p=.016) as an independent predictor for readmissions and male sex was associated with a decreased risk (OR 0.58, p=.016) during consolidation therapy; meanwhile, Philadelphia positive ALL (Ph+ALL) was negatively associated with RaR for R/R ALL pts (OR 0.33, p=.014). (Table 2) There was no significant association between the commonly used L.A.C.E. score and the risk of readmissions among consolidation and R/R ALL pts. However, during induction, a higher L.A.C.E score was negatively associated with the risk of readmission (OR 0.30, p=.027), likely due to a longer duration of hospital stay for high-risk patients (18 days vs. 8 days, p=.000). The 30-day mortality rate and inpatient mortality rate was 3% for unplanned induction readmissions, 0% for consolidation, and 13% for R/R ALL. One patient (3%) died after readmission during induction due to infection. The 30-day mortality rate after readmission for R/R ALL patients was 13%, with 50% of deaths due to infections and 30% due to disease progression. Conclusions Unplanned 30-day readmissions were frequent among patients with ALL, with similar rates between each sequential line of therapy, and the most common cause was infections. The 30-day mortality remains low for induction and consolidation pts, with a significantly higher risk for ICU stay and 30-day mortality for R/R ALL pts. We identified COPD, female sex, and non-Ph+ ALL as independent predictors for readmission. However, the majority of the pts were younger, with only 24-34% above 55 years of age. Implementing more frequent monitoring and increased precautions in high-risk pts could help reduce mortality in ALL. Disclosures Jain: Aprea Therapeutics: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; ADC Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Fate Therapeutics: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Pfizer: Research Funding. Short:AstraZeneca: Consultancy; Astellas: Research Funding; Amgen: Honoraria; Takeda Oncology: Consultancy, Honoraria, Research Funding. Ravandi:Celgene: Consultancy, Honoraria; Orsenix: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Xencor: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding. Borthakur:Abbvie: Research Funding; Curio Science LLC: Consultancy; Polaris: Research Funding; Jannsen: Research Funding; PTC Therapeutics: Consultancy; Argenx: Consultancy; PTC Therapeutics: Research Funding; GSK: Research Funding; FTC Therapeutics: Consultancy; Treadwell Therapeutics: Consultancy; BMS: Research Funding; AstraZeneca: Research Funding; Novartis: Research Funding; Incyte: Research Funding; Cyclacel: Research Funding; BioLine Rx: Consultancy; Xbiotech USA: Research Funding; BioLine Rx: Research Funding; Oncoceutics: Research Funding; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy. Sasaki:Daiichi Sankyo: Consultancy; Novartis: Consultancy, Research Funding; Pfizer Japan: Consultancy; Otsuka: Honoraria. Cortes:Novartis: Consultancy, Research Funding; Merus: Research Funding; Immunogen: Research Funding; Bristol-Myers Squibb: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; Sun Pharma: Research Funding; Astellas: Research Funding; Telios: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Takeda: Consultancy, Research Funding. Kantarjian:Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria, Research Funding; Ariad: Research Funding; Amgen: Honoraria, Research Funding; Takeda: Honoraria; AbbVie: Honoraria, Research Funding; BMS: Research Funding; Novartis: Research Funding; Astex: Research Funding; Daiichi-Sankyo: Research Funding; Immunogen: Research Funding; Pfizer: Honoraria, Research Funding; Cyclacel: Research Funding; Jazz Pharma: Research Funding. Garcia-Manero:AbbVie: Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Merck: Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Amphivena Therapeutics: Research Funding. Jabbour:AbbVie: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding. Kadia:Incyte: Research Funding; Celgene: Research Funding; Cellenkos: Research Funding; Genentech: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Cyclacel: Research Funding; Novartis: Honoraria; Pulmotec: Research Funding; Abbvie: Honoraria, Research Funding; Ascentage: Research Funding; Astra Zeneca: Research Funding; Amgen: Research Funding; Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Astellas: Research Funding.

Mitochondrial metabolites affect epigenetic marks, but it is largely unknown whether mitochondrial metabolic enzymes can directly localize to the nucleus to regulate stem cell function in AML. Here, we discovered that the mitochondrial enzyme, Hexokinase 2 (HK2), localizes to the nucleus in AML and normal hematopoietic stem cells to maintain stem cell function. We searched for mitochondrial enzymes moonlighting in the nucleus using 8227 AML cells, a low passage primary AML culture model arranged in a hierarchy with functionally defined stem cells in the CD34+CD38-fraction. By immunoblotting and confocal microscopy, we detected HK2 in the nucleus of 8227 cells with higher expression in the nucleus of stem cells vs bulk cells. HK2 is the first and rate-limiting enzyme in glycolysis and phosphorylates glucose. In contrast, other metabolic enzymes including phosphofructokinase, fumarase, pyruvate kinase 2, glucose phosphate isomerase, enolase1, citrate synthase, aconitase 2, and succinate dehydrogenase were not detected in the nucleus of these cells. We also detected HK2, but not these other metabolic enzymes, in the nucleus of OCI-AML2, U937, NB4 and TEX leukemia as well as 8 of 9 primary AML samples. Next, we tested whether nuclear HK2 was functionally important to maintain stem cell function in AML. We over-expressed HK2 tagged with nuclear localizing signals (PKKKRKV and PAAKRVKLD) in 8227 and NB4 leukemia cells. We confirmed selective over-expression of HK2 in the nucleus of these cells without increasing levels in the cytoplasm or mitochondria. Over-expression of nuclear HK2 increased clonogenic growth and inhibited retinoic acid-mediated cell differentiation without changing basal proliferation. Over expression of HK2 also increased engraftment of 8227 cells into mouse marrow. We evaluated the selective inhibition of nuclear HK2 by over-expressing HK2 with an outer mitochondrial localization signal while knocking down total endogenous HK2 with shRNA targeting the 3'UTR of HK2. Selective depletion of nuclear HK2 reduced clonogenic growth, increased AML differentiation after treatment with retinoic, and decreased the percentage of CD34+CD38- 8227 stem cells without changing basal proliferation. To determine whether nuclear HK2 maintains stemness through its kinase activity, we over-expressed a kinase dead double mutant of nuclear HK2(D209A D657A). Nuclear kinase dead HK2 increased clonogenic growth and inhibited differentiation after retinoic acid treatment, demonstrating that HK2 maintains stemness independent of its kinase function. To understand nuclear functions of HK2, we used proximity-dependent biotin labeling (BioID) and mass spectrometry to identify proteins that interact with nuclear HK2 and identified proteins related to chromatin organization and regulation. Therefore, we examined the impact of nuclear HK2 on chromatin accessibility using ATAC-seq. Over expression of nuclear HK2 enhanced chromatin accessibility, whereas the selective knockdown of nuclear HK2 compacted chromatin. In summary, we discovered that HK2 localizes to nucleus of AML cells and functions independent of its kinase activity to maintain the stem/progenitor state of AML. Thus, we define a new role for mitochondrial enzymes in the regulation of leukemic stemness and differentiation. Disclosures Dick: Bristol-Myers Squibb/Celgene: Research Funding. Schimmer:Takeda: Honoraria, Research Funding; Novartis: Honoraria; Jazz: Honoraria; Otsuka: Honoraria; Medivir AB: Research Funding; AbbVie Pharmaceuticals: Other: owns stock .

Background: The TP53 gene is mutated in approximately half of human cancers and in up to 20% of acute myeloid leukemia (AML). TP53 mutations are associated with complex karyotype, high rates of resistance to standard treatment, and dismal outcome. However, new AML therapies are being developed that may potentially target these mutations (e.g. APR-246) or are largely ineffective in the context of mutated TP53 (e.g. MDM2 inhibitors). We sought to evaluate the frequency of treatment-emergent TP53 mutations in patients (pts) with TP53 wild type (WT) AML who relapsed or were refractory to therapy. Methods: This is a retrospective analysis of 1293 pts with WT TP53 AML who were treated at our institution with frontline therapy between December 2012 and March 2020. Pts with core binding factor (CBF) AML, those who did not have mutational data at baseline, or those in whom mutation profiling was not performed at relapse were excluded from the analysis. To identify TP53 mutations at baseline or relapse, a targeted next-generation sequencing (NGS) platform was performed. The analytical sensitivity of this NGS panel was established at 1-2% mutant reads in a background of WT reads. Mutations were manually reviewed to exclude any artifacts. Results: We identified 200 pts with non-CBF TP53 WT AML at diagnosis who relapsed after or were refractory to frontline therapy and are the subject of this analysis. Figure 1 shows the pt selection process. The baseline characteristics are shown in Table 1. At diagnosis, the median age was 69 years (range, 17-94 years). By ELN classification, 85 pts (43%) were adverse risk, 94 (47%) were intermediate risk, and 21 (11%) were favorable risk. Eighty-five pts (43%) were refractory to frontline therapy, and 115 (58%) relapsed after frontline therapy. Sixty-nine pts (35%) received intensive chemotherapy and 131 pts (66%) receiver low-intensity therapy. Overall, 29 pts (15%) developed a newly detectable TP53 mutation at some point over the course of therapy in the context of relapsed/refractory disease. Nineteen of these pts (66%) acquired a new detectable mutation after the first line of therapy, 6 pts (21%) after two lines of therapy, and 4 pts (14%) after three lines of therapy. Twenty-four pts (83%) acquired 1 TP53 mutation and 5 pts (17%) developed 2 TP53 mutations. The median variant allelic frequency (VAF) of the TP53 mutation was 15% (range 1.1% - 95.6%). Baseline factors associated with an increased likelihood of developing a new TP53 mutation included chromosome 5 abnormality (new TP53 mutation 40% vs. 12% in those without; P=0.02) and presence of an IDH2 mutation (28% vs. 12%, respectively; P=0.02). Development of a new TP53 mutation was more common after high-intensity therapy (23% vs. 10% after low-intensity therapy; P=0.02) and were also more common after hematopoietic stem cell transplant (HSCT) compared to those who did not undergo HSCT (36% vs. 12%, respectively; P=0.005). Thirteen (45%) of the new TP53 mutations occurred in the context of complex cytogenetics. Interestingly, in 7 of these cases, both the cytogenetic complexity and TP53 mutation emerged concomitantly and were not present at baseline. Among pts who developed new detectable TP53 mutations, the most common co-mutations were DDX41, DNMT3A, IDH2 and NRAS (each present in 15-20% of TP53-mutated cases). Seventeen (59%) of the 29 pts with new TP53 mutation responded to salvage therapy, and 7 underwent subsequent HSCT. Overall, survival was poor after development of newly detected TP53 mutation. The median overall survival (OS) after acquisition of TP53 mutation was 5.0 months, with a 1-year OS rate of 17% (Figure 2). Interestingly, we also identified a new detectable TP53 mutation in 5 pts (1%) out of the 555 pts who were in complete remission. The median VAF at the time of mutant TP53 acquisition was 2.5% (range 1.0% - 3.3%). With a median follow-up of 27 months since detection of the new TP53 mutation, none of these pts have developed hematologic relapse. Conclusion: We identified one or more newly detectable TP53 mutation(s) over the course of disease in 15% pts with relapsed/refractory AML. These mutations tended to be subclonal with a median VAF of 15%. New TP53 mutations were more common after intensive chemotherapy and/or HSCT. Our data suggest that these mutations may be acquired throughout the course of therapy, and therefore sequential monitoring may be relevant in the era of new potential TP53-targeting therapies. Disclosures Daver: Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Konopleva:Eli Lilly: Research Funding; Agios: Research Funding; Cellectis: Research Funding; Amgen: Consultancy; AbbVie: Consultancy, Research Funding; Rafael Pharmaceutical: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Ablynx: Research Funding; Kisoji: Consultancy; AstraZeneca: Research Funding; Ascentage: Research Funding; Genentech: Consultancy, Research Funding; Calithera: Research Funding; Forty-Seven: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Sanofi: Research Funding. Ravandi:Celgene: Consultancy, Honoraria; Xencor: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Macrogenics: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding. Kadia:Astellas: Research Funding; Abbvie: Honoraria, Research Funding; JAZZ: Honoraria, Research Funding; Amgen: Research Funding; Novartis: Honoraria; Incyte: Research Funding; Astra Zeneca: Research Funding; Pfizer: Honoraria, Research Funding; Cellenkos: Research Funding; Cyclacel: Research Funding; Ascentage: Research Funding; Celgene: Research Funding; BMS: Honoraria, Research Funding; Pulmotec: Research Funding; Genentech: Honoraria, Research Funding. DiNardo:MedImmune: Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; ImmuneOnc: Honoraria; Agios: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Calithera: Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Novartis: Consultancy; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; Syros: Honoraria; Jazz: Honoraria. Issa:Celegene: Research Funding; Syndax: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Borthakur:Oncoceutics: Research Funding; BioLine Rx: Research Funding; Treadwell Therapeutics: Consultancy; Xbiotech USA: Research Funding; BMS: Research Funding; AstraZeneca: Research Funding; PTC Therapeutics: Research Funding; Incyte: Research Funding; Polaris: Research Funding; Jannsen: Research Funding; GSK: Research Funding; Novartis: Research Funding; Abbvie: Research Funding; Curio Science LLC: Consultancy; FTC Therapeutics: Consultancy; Argenx: Consultancy; PTC Therapeutics: Consultancy; BioLine Rx: Consultancy; BioTherix: Consultancy; Nkarta Therapeutics: Consultancy; Cyclacel: Research Funding. Yilmaz:Daicho Sankyo: Research Funding; Pfizer: Research Funding; Pint Pharma: Honoraria. Maiti:Celgene: Research Funding. Kantarjian:Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Cyclacel: Research Funding; Daiichi-Sankyo: Research Funding; Astex: Research Funding; Immunogen: Research Funding; Jazz Pharma: Research Funding; Pfizer: Honoraria, Research Funding; BMS: Research Funding; AbbVie: Honoraria, Research Funding; Takeda: Honoraria; Amgen: Honoraria, Research Funding; Ariad: Research Funding; Agios: Honoraria, Research Funding; Novartis: Research Funding. Short:AstraZeneca: Consultancy; Amgen: Honoraria; Astellas: Research Funding; Takeda Oncology: Consultancy, Honoraria, Research Funding.

INTRODUCTION: Pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are heterogeneous diseases mediated by changes in protein expression. As most chemotherapeutic agents target proteins, and because overall survival of pediatric AML is far inferior to both pre-B and T-ALL, we aimed to compare the proteomic landscape of pediatric T-ALL and AML, with the goal of determining common AML-T-ALL pathways that are potentially targetable with novel agents. METHODS: Reverse phase protein arrays (RPPA) analysis was used to measure protein expression in 858 acute leukemia samples (358 T-ALL and 500 AML, 723 pediatric (< 18 yrs.), 135 adults (≥18 yrs.)) and 61 normal CD34+ samples using 270 validated antibodies. Expression levels were normalized against CD34+ cells. Proteins were allocated into 30 functionally related subgroups (Protein Functional Group (PFG)). A progeny clustering algorithm was applied to each PFG to search for strong correlations between proteins and to identify an optimal number of Protein Clusters (PC). Block clustering identified PC that recurrently co-occurred together (Protein Constellation (CON)) and patients that expressed similar combination of CON were defined as Protein Signature (SIG). Proteins that were differentially expressed were identified using the Student's t-test or ANOVA, with a Bonferroni adjusted p-value (0.05/ 270 = 0.00019)). RESULTS: Of the 270 analyzed proteins, 131 proteins (49%) were differentially expressed between T-ALL and AML; 60 were higher in T-ALL, 71 in AML. Similar to our previous analysis in adult AML and ALL, cell cycle regulators (CDKN1A, CDKN1B) and 2 of the 5 histone marks (H3K36Me3 & H3K4Me3) were higher expressed in T-ALL compared to AML. Heat shock proteins (HSP90AA1_B1, HSPA1A_L, HSPB1 and HSPB1-pSer82) were higher in AML as well as translation proteins EIF2S1, EIF4E and EIF4EBP1 and ribosomal proteins RPS6-pSer235_236 and RPS6KB1, while expression of the translation inhibitory proteins EIF2S1-pSer51 and EIF2AK2-pThr451 was lower in AML compared to T-ALL. Next, cluster analysis in the context of 30 PFG resulted in 133 PC. The majority (n=102) of PC were expressed in both diseases, 30 PC (22.6%) were AML-specific, and only one PC was specific to T-ALL (characterized by high CDKN1A, CDKN1B and CCND1, but low WEE1, CCNB1 and RB1-pSer). Co-clustering of the 133 PC identified 14 CON that formed 17 SIG. Three CON (5, 9, 10) were associated with AML, 2 with T-ALL (2, 13) and 8 CON were observed in both diseases. In contrast, 15 of SIG were associated with either T-ALL or AML, and two SIG (9, 10) included a mixture of both diseases (P < 0.001, annotation bar Figure 1 "Disease")). SIG were associated with gender (P < 0.001), but not with CNS-status and ethnicity (Hispanic vs. non-Hispanic). No age-specific (kids vs. adults) signatures were observed. For each SIG and CON, proteins significantly higher or lower expressed compared to the normal CD34+ cells were identified. CONCLUSIONS: This study provides support for our previous hypothesis that pediatric T-ALL and AML can be characterized by recurrent protein expression patterns. While most PC and CON were found in both diseases, SIG (i.e. combinations of protein expression patterns) were specific to either T-ALL or AML. We found similar results when comparing B-ALL to AML in adults. Shared CON indicate that there are common protein expression patterns between pediatric T-ALL and AML. Proteins or pathways with similar utilization (e.g. CON3, 5) in both diseases may allow for information on clinical utility from one disease to be applicable to the other. Those with differential utilization are likely to be uninformative with respect to clinical utility in the other disease. Figure. "MetaGalaxy" analysis for pediatric AML and T-ALL. Each row represents one protein clusters (n = 133), each column represents one patient (n = 858). Blue indicates membership for that particular protein cluster. Annotation bar shows strong correlation with disease (yellow = T-ALL, blue = AML). No associations were seen for age (blue = adult, pink = pediatric) or Ethnicity (blue = Hispanic, yellow = non-Hispanic). Figure 1 Disclosures No relevant conflicts of interest to declare.

Introduction Pediatric chronic myeloid leukemia (CML) accounts for 10-15% of pediatric myeloid leukemias and 2-9% of all pediatric leukemias. There are several unique characteristics of CML diagnosed in children, adolescents, and young adults, compared to adults. They present with higher white blood counts and larger spleens, suggesting that the biology of pediatric CML is different from adult CML. We hypothesize that the differences in clinical presentation of pediatric CML patients are due to unique molecular characteristics that differ from adult CML patients. To test this hypothesis, we studied the transcriptomic signature of pediatric CD34+ CML cells compared to adult CML and normal age-matched bone marrow CD34+ cells. Methods CD34+ cells were isolated by FACS from pediatric CML (n=9), adult CML (n=10), pediatric normal (n=10) and adult normal (n=10) bone marrow samples. Total RNA was isolated from cells, and cDNA libraries were generated. Prepared libraries were sequenced on the Illumina HiSeq 4000 instrument. Raw sequences were trimmed and aligned to the hg38 reference genome with STAR/2.5.1b aligner. Gene level counts were determined with STAR -quantMode option using gene annotations from GENCODE (p5). Differential gene expression and pathway analysis were conducted with R/3.5.3. Counts were normalized with trimmed mean of M-values (TMM) from the EdgeR/ 3.24.3 package and further transformed with VOOM from the Limma/ 3.38.3 package. A linear model using the empirical Bayes analysis pipeline also from Limma was then used to obtain p-values, adjusted p-values and log-fold changes (LogFC). We performed three comparisons: (1) Pediatric CML vs Normal, (2) Adult CML vs Normal, and (3) Pediatric CML vs Adult CML. A False Discovery Rate (FDR) of £ .05 and absolute log2 fold-change > 1 was used to define differentially expressed genes in each comparison. Over-representation analysis was used to identify potentially unique pathways based on differentially expressed genes. Clinical and demographic features at diagnosis were extracted for pediatric and adult CML patients and compared using Fisher's exact test (categorical variables) or Wilcoxon rank sum test (continuous variables). Results Pediatric patients were diagnosed with CML at a median of 11 years (interquartile range (IQR): 10-14) compared to 54 years (IQR: 33-62) for adult patients. At diagnosis, pediatric patients had higher platelet counts (p=0.001) and larger spleen sizes (p=0.010) than adult patients, whereas the white blood cell count and phase at diagnosis did not differ. We found 606 genes (210 up- and 396 down-regulated) differentially expressed in pediatric CML CD34+ cells compared to pediatric normal controls. Interestingly, transcriptional regulators involved in blood cell differentiation including GATA1, TAL1, and KLF1 were differentially enriched in pediatric CML. In comparing adult CML patients to normal adult CD34+ cells, we found 920 genes (379 up- and 541 down-regulated) differentially expressed. Among all dysregulated genes we identified (1352 genes), 174 genes (54 up- and 120-down-regulated) overlapped when comparing pediatric and adult CML patients. Significantly enriched pathways in both adult and pediatric CML cells included PI3K/AKT signaling, MAPK signaling, and Notch/Wnt signaling, which have been previously reported. We found 437 unique genes that were dysregulated only in pediatric CML (270 up- and 167 down-regulated). Notch/Wnt signaling and Rho signaling pathways were significantly enriched. DLC1, a tumor suppressor gene that encodes a RhoGTPase-activating protein, has been known to be downregulated in solid tumors and hematologic malignancies. Interestingly, our data showed that DLC1 is significantly upregulated by 3-fold (p=0.0238) in pediatric CML, but not adult CML CD34+ cells. In addition, we observed that ABR, an inducer of C/EBPa that encodes an activator of RhoGEF and GTPase, was significantly downregulated by 2-fold (p=0.0119) in pediatric but not in adult CML CD34+ cells. Conclusion These results demonstrate unique molecular characteristics of pediatric CML that may contribute to the clinical differences at presentation between adult and pediatric disease. A better understanding of the particular biology of pediatric CML might impact the treatment of those patients in the future. Disclosures Gotlib: Deciphera: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: co-chair of the Study Steering Committee and Research Funding; Blueprint Medicines Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Chair of the Response Adjudication Committee and Research Funding, Research Funding.

Disease relapse remains the major cause of treatment failure following hematopoietic transplantation for AML/MDS. A major goal is to develop more effective antileukemic regimens without excessive toxicity. Fludarabine (Flu) with IV Busulfan (Bu) recently has replaced TBI- and double alkylator regimens in pretransplant conditioning because of its improved safety. Post-transplant relapse is still a major concern. Clofarabine (Clo) has improved antileukemic activity compared with Flu, and cell line studies indicated that Flu and Clo with Bu may be synergistic and superior to Flu alone with Bu. We previously conducted a phase II study of different combinations of Flu and Clo with Bu; the best results were obtained with Flu 10 mg/m2 and Clo 30 mg/m2 daily, with Bu, in four daily doses. We then performed a phase III randomized controlled trial comparing Flu-Clo-Bu (FCB) with our standard Flu-Bu regimen. Busulfan was given with PK-guided dosing to an average daily AUC of 6000 mM-min for age ≤60 and 4000 mM-min for patient ages 61-70. GVHD prophylaxis was tacrolimus-mini methotrexate. Unrelated donor recipients received low-dose rabbit ATG, total dose of 4 mg/kg. Patients aged 3-70 with intermediate or high risk AML or MDS, with PS>70% and adequate organ function were eligible if they had an HLA identical related or 9/10 or 10/10 matched unrelated donor. There was no restriction for preexisting comorbid conditions. Patients were stratified based on disease status, complete remission (CR) vs. no CR (NCR). 250 patients were randomized; 120 received FCB and 130 got Flu-Bu. 95 had a matched sibling, 155 a matched unrelated donor. Median age was 51 yrs. 181 had AML, 69 MDS, and 92 (37%) had poor risk cytogenetics. 133 patients were in remission; 117 had active disease. Comorbidity indices (HCT-CI) varied from 0-10 and were evenly distributed between the groups. Performance status was >90% in 88%. All evaluable patients (n=249) achieved engraftment. 95 (38%) developed grade 2 and 16 (6%) grade 3-4 acute GVHD, while 93 (39%) got chronic GVHD. The median progression-free survival (PFS) for the FCB group was 39.3 mos and for the Flu-Bu group was 28.1 mos. There was a significantly lower risk of progression with FCB (p=0.025), but this benefit was offset by a higher risk of NRM (p=0.018) (Fig. a). There was no significant difference in PFS for patients in CR, but [NCR age ≤60 years] patients had median PFS of 28 mos with FCB vs. 8 mos with Flu-Bu (Fig. b). For patients age > 60 years, FCB yielded a median PFS ~25 mos compared with 6 mos with Flu-Bu (Fig. c). Additional analysis revealed that NCR patients with a low HCT-CI (0-2) benefited more from FCB than from Flu-Bu. The overall survival (OS) for the (NCR, HCT 0-2) group was also longer with FCB than with Flu-Bu (Fig. d). A Bayesian regression analysis including treatment-covariate interactions showed that most of the benefit of FCB was seen in this subgroup, while patients with HCT scores of ≥3 were less likely to benefit overall from FCB due to higher TRM with FCB. Our trial demonstrates the safety of the FCB regimen in patients with HCT 0-2 and better disease control with FCB compared with Flu-Bu in NCR patients. Patients with ≥3 comorbid conditions are at increased risk for TRM associated with FCB, somewhat offsetting the antileukemic benefit. Thus, clinical application of FCB should take CR status and performance status into account, and also include a personalized assessment of the risk for treatment-related complications based on the nature and number of preexisting comorbid conditions. Finally, age did not play a role for the use of FCB; it can be safely utilized in appropriate patients up to 70 years of age, and can be expected to yield better disease control. Figure Disclosures Alousi: Therakos: Research Funding; Incyte: Honoraria, Research Funding; Alexion: Honoraria. Bashir:Amgen: Other: Advisory Board; Purdue: Other: Advisory Board; KITE: Other: Advisory Board; Takeda: Other: Advisory Board, Research Funding; Celgene: Research Funding; Acrotech: Research Funding; StemLine: Research Funding. Ciurea:Kiadis Pharma: Current equity holder in publicly-traded company, Research Funding. Hosing:NKARTA Inc.: Consultancy. Kebriaei:Pfizer: Other: Served on advisory board; Ziopharm: Other: Research Support; Novartis: Other: Served on advisory board; Amgen: Other: Research Support; Kite: Other: Served on advisory board; Jazz: Consultancy. Oran:Celgene: Consultancy; ASTEX: Research Funding; Arog Pharmaceuticals: Research Funding. Rezvani:Pharmacyclics: Other: Educational grant; Formula Pharma: Membership on an entity's Board of Directors or advisory committees; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; GemoAb: Membership on an entity's Board of Directors or advisory committees; Virogen: Membership on an entity's Board of Directors or advisory committees; Affimed: Other: Educational grant; Takeda: Other: Licensing agreement. Shah:BMS, Janssen, Bluebird Bio, Sutro Biopharma, Teneobio, Poseida, Nektar: Research Funding; GSK, Amgen, Indapta Therapeutics, Sanofi, BMS, CareDx, Kite, Karyopharm: Consultancy. Shpall:Adaptimmune: Membership on an entity's Board of Directors or advisory committees; Zelluna: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Licensing Agreement; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Magenta: Membership on an entity's Board of Directors or advisory committees. Parmar:Cellenkos Inc.: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Popat:Bayer: Research Funding; Novartis: Research Funding. Nieto:Secura Bio: Other: Grant Support; Astra Zeneca: Other: Grant Support; Novartis: Other: Grant Support; Affimed: Consultancy, Other: Grant Support. Champlin:Omeros: Consultancy; Takeda: Patents & Royalties; Actinium: Consultancy; DKMS America: Membership on an entity's Board of Directors or advisory committees; Cytonus: Consultancy; Genzyme: Speakers Bureau; Johnson and Johnson: Consultancy. OffLabel Disclosure: The use of fludarabine and clofarabine is not approved by the FDA in pretranpslant conditioning therapy.

Venetoclax (VEN), a highly selective BCL-2 inhibitor with limited single-agent activity in AML, has shown encouraging efficacy in combination with hypomethylating agents (HMA). Nevertheless, patients relapse and have limited treatment options. Like BCL-2, MCL-1 plays critical roles in the survival of AML cells and AML stem/progenitor cells. MCL-1 is also a known resistance factor to VEN. Preclinical studies have demonstrated that combined inhibition of BCL-2 and MCL-1 is highly effective in VEN-resistant AML cells. Diverse mechanisms contribute to the resistance to VEN, and likely also to BH3 mimetics targeting MCL-1 that are currently under clinical development in AML. The effectiveness of co-targeting BCL-2 and MCL-1 in the setting of various resistance mechanisms has not been fully explored. We investigated combined inhibition of BCL-2 and MCL-1 in AML cells resistant to apoptotic stimuli through various mechanisms and demonstrate that co-inhibition of BCL-2 with VEN and MCL-1 with AMG176 synergistically targets AML cells that exhibit intrinsic or acquired resistance to BH3 mimetics in vitro and in vivo. We generated AML cells with acquired resistance to VEN (VEN-R) or AMG176 (AMG-R) by exposing the cells to increased doses of the drug and we also generated the cells genetically overexpressing BCL-2, MCL-1, or BCL-2A1. We found that both VEN-R and AMG-R MV4-11 cells expressed increased levels of MCL-1, BCL-2, and BCL2A1, but decreased BAX. Although BCL-XL levels decreased in AMG-R MV4-11 cells, BAK, PUMA, and BID levels were also markedly lower in these resistant cells compared to the parental controls. VEN or AMG176 as single agents had diminished activity against AML cells with acquired resistance not only to VEN, but also to AMG176 and AML cells genetically overexpressing MCL-1, BCL-2, or BCL2-A1. In addition, we found that TP53 mutated primary AML cells expressed low levels of BAX and that Molm13 cells acquired a TP53 mutation (R248W) expressed lower levels of BAX and were more resistant to VEN, consistent with clinical observations, and they were also more resistant to AMG176. However, when VEN and AMG176 were combined, synergy was observed (combination index < 1). We next treated AML patient samples and found that combined inhibition of BCL-2 and MCL-1 was synergistic in primary AML cells and stem/progenitor cells obtained from patients with various cytogenetics/mutations, including TP53 mutations, and from patients resistant to/relapsed from VEN- or VEN/HMA-based therapy, even when AML cells were co-cultured with bone marrow-derived mesenchymal stromal cells that mimic the bone marrow microenvironment. To demonstrate potential clinical relevance, we developed a PDX model from a clinically-acquired VEN/HMA resistant AML patient and treated the PDX-bearing mice with VEN, AMG176, and the combination. Remarkably, the combination of VEN and AMG176 demonstrated strong antileukemia activities, markedly diminished not only AML blasts but also AML stem/progenitor cells, as determined by CyTOF analysis, and significantly extended survival (median 336 vs 126 d for controls, P < 0001), while VEN (129 d) alone and even AMG176 (131 d) alone had minimal efficacy. Several mice in the combination group survived over 400 d and died probably from old age with only minimal residual leukemia. In conclusion, we demonstrate the alteration of multiple BCL-2 family proteins contributes to BH3 mimetic resistance that can be overcome by combined inhibition of MCL-1 and BCL-2. The striking effectiveness of co-targeting BCL-2 and MCL-1 in AML resistance to a BH3 mimetic via various mechanisms or to VEN/HMA suggests broad clinical applications of this strategy, and warrants clinical evaluations. Disclosures Carter: Amgen: Research Funding; Ascentage: Research Funding; Syndax: Research Funding; AstraZeneca: Research Funding. Hughes:Amgen: Current Employment. Chen:Amgen: Current Employment. Morrow:Amgen: Current Employment. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding.

Background: Heat shock factor 1 (HSF1) is a key-component of the heat shock response and plays a major role in cancer biology. The heat shock response is a highly conserved mechanism that is important for cell survival under stressful conditions. It facilitates normal protein folding and guards the proteome from misfolding and aggregation. Bortezomib (BTZ) is a reversible proteasome inhibitor and was recently tested in a phase 3 clinical trial for patients with de novo pediatric acute myeloid leukemia (pedi-AML). This trial compared standard therapy (cytarabine/daunorubicin/etoposide (ADE)) to ADE plus BTZ (ADE+B). As HSF1 and BTZ act in opposing circumstances, our goal was to globally assess the phosphorylation of HSF1 at serine 326 (HSF1.pS326) and to determine if baseline HSF1.pS326 was prognostic of clinical response to ADE+B and if we could identify a subset of patients that benefitted from ADE+B. Methods: Reverse phase protein array (RPPA) probed with 222 total antibodies and 69 specific post-translationally modified proteins was used to determine the protein expression levels in 505 bulk leukemic pedi-AML samples compared to 20 CD34+ samples from healthy pediatric donors. Patients participated in the Children's Oncology Group (COG) AAML1031 Phase 3 clinical trial that compared ADE to ADE+B. Survival curves were generated using the Kaplan-Meier method. Results: HSF1.pS326 protein expression levels in the pedi-AML patient samples. Based on the HSF1.pS326 expression levels, patients were classified into two clusters; high HSF1 326 (n = 216) and low HSF1.326 (n = 289). The median of the normal CD34+ samples was used as cut-off point. Expression of HSF1.pS326 was not prognostic for outcome in patients treated with ADE (event-free survival (EFS), p = 0.51) (Fig. 1A). In patients that were treated with ADE+B however, HSF1.pS326 levels were highly prognostic, with low HSF1.pS326 associated with a better EFS (p = 0.009) (Fig. 1B). Patients with high HSF1.pS326 did not benefit from BTZ addition (EFS, p = 0.77) (Fig. 1C), whereas patients with low HSF1.pS326 levels significantly improved (EFS, p = 0.004) (Fig. 1D). Between the two patient clusters, the NPM1 mutation state was higher in patients with high HSF1.pS326 levels (p = 0.042), and the CEBPA mutation state was higher in patients with low HSF1.pS326 (p = 0.011). No other patient or disease characteristics were different between the two clusters. To functionally validate our findings, we overexpressed wild type or mutant HSF1 in 293T cells and assessed its effect on BTZ sensitivity. The mutant HSF1 constructs contained amino acid substitutions at Ser326, resulting in either a phospho-mimic HSF1 (S326E), or a phospho-dead HSF1 protein (S326A). Cell viability analysis showed clear resistance to BTZ in cells with increased phosphorylation (HSF1 S326E) (Fig. 1E - blue curve). Cells that expressed reduced phosphorylation of HSF1 (HSF1 S326A), however were highly sensitive to BTZ (Fig. 1E, red curve). This confirms our observations from the pedi-AML patients. Conclusions: Using a proteomics approach, we identified a subgroup of pedi-AML patients that benefitted from BTZ addition to ADE therapy. We hypothesize that patients with low HSF1 activation are more susceptible to protein cell stress, and protein cell stress susceptibility is amplified by the addition of BTZ with ADE. The use of HSF1.pS326 as potential biomarker could identify patients that would benefit from ADE+B therapy. Patients with high HSF1 could potentially benefit from ADE+B in combination with a HSF1 (phospho) inhibitor, suggesting a novel combinational therapy. Figure 1. Kaplan Meier survival curves for EFS based on HSF1.pS326 expression. A. HSF1.pS326 did not affect outcome in ADE treated patients (high HSF1.PS326 shown in red, low HSF1.pS326 in blue). B. HSF1.pS326 was highly prognostic for EFS ADE+B. C. Patients with high HSF1.pS326 did not benefit from BTZ (ADE shown in blue, ADE+B in green). D. Patients that expressed low HSF1.pS326 did significantly better after ADE+B. E. To assess the effect of high and low HSF1.pS326 on BTZ sensitivity, 293T cells were transfected with two HSF1.pS326 mutants that mimicked high (blue) and low (red) HSF1.pS326 patients, in addition to wild type HSF1 (orange) and an empty vector as control (green). Cell viability assays showed resistance to BTZ in the phospho-mimic (blue) mutant, whereas the phospho-dead (red) mutant was sensitive to BTZ. Figure 1. Figure 1. Disclosures Kolb: Roche- Genentech: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees.

Acute myeloid leukemia (AML) with an FLT3 internal tandem duplication (FLT3-ITD) mutation is an aggressive hematologic malignancy with a grave prognosis. To identify the mutational spectrum associated with relapse, whole-exome sequencing was performed on 13 matched diagnosis, relapse, and remission trios followed by targeted sequencing of 299 genes in 67 FLT3-ITD patients. The FLT3-ITD genome has an average of 13 mutations per sample, similar to other AML subtypes, which is a low mutation rate compared with that in solid tumors. Recurrent mutations occur in genes related to DNA methylation, chromatin, histone methylation, myeloid transcription factors, signaling, adhesion, cohesin complex, and the spliceosome. Their pattern of mutual exclusivity and cooperation among mutated genes suggests that these genes have a strong biological relationship. In addition, we identified mutations in previously unappreciated genes such as MLL3, NSD1, FAT1, FAT4, and IDH3B. Mutations in 9 genes were observed in the relapse-specific phase. DNMT3A mutations are the most stable mutations, and this DNMT3A-transformed clone can be present even in morphologic complete remissions. Of note, all AML matched trio samples shared at least 1 genomic alteration at diagnosis and relapse, suggesting common ancestral clones. Two types of clonal evolution occur at relapse: either the founder clone recurs or a subclone of the founder clone escapes from induction chemotherapy and expands at relapse by acquiring new mutations. Relapse-specific mutations displayed an increase in transversions. Functional assays demonstrated that both MLL3 and FAT1 exert tumor-suppressor activity in the FLT3-ITD subtype. An inhibitor of XPO1 synergized with standard AML induction chemotherapy to inhibit FLT3-ITD growth. This study clearly shows that FLT3-ITD AML requires additional driver genetic alterations in addition to FLT3-ITD alone.

In spite of recent progress in AML therapy, the outcomes of TP53 mutated AML remain extremely poor. The FDA-approved combination of Bcl-2 inhibition by venetoclax (VEN) with hypomethylating agents is resulting in CR/CRi rates of 70-95% and good tolerability in elderly AML patients. However, patients with TP53 mutations achieve lower response rates (CR/CRi 47%) (DiNardo CD et al., Lancet Oncol 2018; DiNardo CD et al., Blood 2019) and invariably relapse. Combined Bcl-2 inhibition and p53 activation is synthetic lethal in TP53 wild-type AML in part through targeting Mcl-1 (Pan R et al., Cancer Cell 2016). In TP53 deficient/mutant AML, direct targeting of Mcl-1 may partially compensate for the TP53 defect. We therefore postulate that combined inhibition of Mcl-1 and Bcl-2 effectively induces apoptosis in TP53 deficient/mutant AML cells. Reverse phase protein array analysis of a large cohort of newly diagnosed AML patients (n=511) enabled us to stratify patients into various prognostic groups based on p53 pathway protein expression, which included 8 core proteins: TP53, TP53pS15, MDM2, MDM4, TRIM24, SFN, IRS1.pS1101, and YWHAZ. The group with p53 pathway dysfunction, defined by high p53 protein levels, is characterized by poor outcomes (Quintas-Cardama A et al., Leukemia 2017). This group, encompassing both TP53 wild-type and TP53 mutations, had significantly lower expression of Bax (p=0.0007), the chief executioner of intrinsic apoptosis. A survey of Bcl-2 family proteins in TP53 wild-type and mutant AML showed that only Bax was significantly lower in patients with TP53 mutations (p=0.0498). We next investigated the roles of p53 in response to BH3 mimetics in TP53 wild-type and knockdown (KD) OCI-AML3 cells and in TP53 wild-type and mutant Molm13 cells, generated by long-term exposure of TP53 wild-type Molm13 cells to RG7388 (idasanutlin). Western blot analysis showed that Bax protein was consistently decreased in both TP53 KD and mutant cell lines compared to their respective controls. p53 KD OCI-AML3 and TP53 mutant Molm13 cells exhibited decreased sensitivity not only to VEN, but also to Mcl-1 inhibitor AZD5991 compared to OCI-AML3 vector control and Molm13 parental cells, respectively. To investigate if combined inhibition of Bcl-2 and Mcl-1 could counter-balance the loss of TP53 activity, p53 KD and TP53 mutated AML cells were treated with VEN and AZD5991: like in their respective control cells, the combination synergistically induced cell death in these cells (Fig. 1). The EC50 levels of VEN required for the described synergism in OCI-AML3 cells can easily be reached/exceeded clinically. The combination was also synergistic in leukemia cell lines lacking wild-type TP53 such as KG-1 and U937. Importantly, the combined inhibition was more effective than each single agent in primary AML cells and stem/progenitor cells lacking wild-type TP53 due to deletion of chromosome 17 or mutations in TP53 gene. Conclusion: AML cells deficient in functional TP53 have decreased Bax protein expression, increased apoptotic threshold and are more resistant to individual BH3 mimetics. Combined inhibition of Bcl-2 and Mcl-1 is highly synergistic in p53 deficient/mutant AML. Disclosures Carter: Amgen: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding. Cidado:AstraZeneca: Employment. Drew:AstraZeneca: Employment. Andreeff:BiolineRx: Membership on an entity's Board of Directors or advisory committees; CLL Foundation: Membership on an entity's Board of Directors or advisory committees; NCI-RDCRN (Rare Disease Cliln Network): Membership on an entity's Board of Directors or advisory committees; Leukemia Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; German Research Council: Membership on an entity's Board of Directors or advisory committees; NCI-CTEP: Membership on an entity's Board of Directors or advisory committees; Cancer UK: Membership on an entity's Board of Directors or advisory committees; Center for Drug Research & Development: Membership on an entity's Board of Directors or advisory committees; NIH/NCI: Research Funding; CPRIT: Research Funding; Breast Cancer Research Foundation: Research Funding; Oncolyze: Equity Ownership; Oncoceutics: Equity Ownership; Senti Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eutropics: Equity Ownership; Aptose: Equity Ownership; Reata: Equity Ownership; 6 Dimensions Capital: Consultancy; AstaZeneca: Consultancy; Daiichi Sankyo, Inc.: Consultancy, Patents & Royalties: Patents licensed, royalty bearing, Research Funding; Jazz Pharmaceuticals: Consultancy; Celgene: Consultancy; Amgen: Consultancy.