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Purpose:A phase I/II study evaluating the safety and activity of memory-enriched CD19-directed chimeric antigen receptor (CD19-CAR) T cells in adults with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL).Patients and Methods:In phase I, we tested sequentially two cell populations for CAR transduction: (i) central memory (Tcm) or (ii) naïve, stem, and central memory (Tn/mem) T cells. The study employed an activity constrained for toxicity design to determine the recommended phase II dose (RP2D), which was tested in phase II.Results:The Tcm cohort was closed early due to lack of activity. The 200 ×106 Tn/mem-derived CD19-CAR T-cell dose was found to be safe and active, and was declared the RP2D. At RP2D, 58 participants underwent leukapheresis and 46 received CD19-CAR T cells. Median age for treated participants was 38 years (range, 22–72). Twenty-nine (63%) participants had relapsed post-allogeneic hematopoietic cell transplantation (alloHCT), 18 (39%) had Philadelphia-like (Ph-like) genotype, and 16 (35%) had extramedullary disease (EMD) at lymphodepletion (LD). Three (7%) participants had grade 3 cytokine release syndrome (CRS), and none had grade ≥ 4 CRS. Eight (17%) participants had grade ≥ 3 neurotoxicity, including one fatal cerebral edema. Forty (87%) patients achieved complete remission (CR)/CR with incomplete hematologic recovery, 2 (4%) progressed, and 4 (9%) were unevaluable for response. Among 42 response-evaluable participants, 16/17 with Ph-like ALL and 13/15 with EMD at LD responded. Twenty-one (53%) responders underwent alloHCT consolidation, which was associated with improved relapse-free survival (adjusted HR = 0.16; 95% confidence interval, 0.05–0.48; P = 0.001).Conclusions:Tn/mem-derived CD19-CAR T cells were safe and active, including in Ph-like ALL and EMD.See related commentary by El Marabti and Abdel-Wahab, p. 694

Toxicity management algorithms

Extramedullary disease at time of lymphodepletion

Purpose:A phase I/II study evaluating the safety and activity of memory-enriched CD19-directed chimeric antigen receptor (CD19-CAR) T cells in adults with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL).Patients and Methods:In phase I, we tested sequentially two cell populations for CAR transduction: (i) central memory (Tcm) or (ii) naïve, stem, and central memory (Tn/mem) T cells. The study employed an activity constrained for toxicity design to determine the recommended phase II dose (RP2D), which was tested in phase II.Results:The Tcm cohort was closed early due to lack of activity. The 200 ×106 Tn/mem-derived CD19-CAR T-cell dose was found to be safe and active, and was declared the RP2D. At RP2D, 58 participants underwent leukapheresis and 46 received CD19-CAR T cells. Median age for treated participants was 38 years (range, 22–72). Twenty-nine (63%) participants had relapsed post-allogeneic hematopoietic cell transplantation (alloHCT), 18 (39%) had Philadelphia-like (Ph-like) genotype, and 16 (35%) had extramedullary disease (EMD) at lymphodepletion (LD). Three (7%) participants had grade 3 cytokine release syndrome (CRS), and none had grade ≥ 4 CRS. Eight (17%) participants had grade ≥ 3 neurotoxicity, including one fatal cerebral edema. Forty (87%) patients achieved complete remission (CR)/CR with incomplete hematologic recovery, 2 (4%) progressed, and 4 (9%) were unevaluable for response. Among 42 response-evaluable participants, 16/17 with Ph-like ALL and 13/15 with EMD at LD responded. Twenty-one (53%) responders underwent alloHCT consolidation, which was associated with improved relapse-free survival (adjusted HR = 0.16; 95% confidence interval, 0.05–0.48; P = 0.001).Conclusions:Tn/mem-derived CD19-CAR T cells were safe and active, including in Ph-like ALL and EMD.See related commentary by El Marabti and Abdel-Wahab, p. 694

MiR-126 and miR-155 are key microRNAs (miRNAs) that regulate, respectively, hematopoietic cell quiescence and proliferation. Herein we showed that in acute myeloid leukemia (AML), the biogenesis of these two miRNAs is interconnected through a network of regulatory loops driven by the FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD). In fact, FLT3-ITD induces the expression of miR-155 through a noncanonical mechanism of miRNA biogenesis that implicates cytoplasmic Drosha ribonuclease III (DROSHA). In turn, miR-155 down-regulates SH2-containing inositol phosphatase 1 (SHIP1), thereby increasing phosphor-protein kinase B (AKT) that in turn serine-phosphorylates, stabilizes, and activates Sprouty related EVH1 domain containing 1 (SPRED1). Activated SPRED1 inhibits the RAN/XPO5 complex and blocks the nucleus-to-cytoplasm transport of pre-miR-126, which cannot then complete the last steps of biogenesis. The net result is aberrantly low levels of mature miR-126 that allow quiescent leukemia blasts to be recruited into the cell cycle and proliferate. Thus, miR-126 down-regulation in proliferating AML blasts is downstream of FLT3-ITD–dependent miR-155 expression that initiates a complex circuit of concatenated regulatory feedback (i.e., miR-126/SPRED1, miR-155/human dead-box protein 3 [DDX3X]) and feed-forward (i.e., miR-155/SHIP1/AKT/miR-126) regulatory loops that eventually converge into an output signal for leukemic growth.

Blinatumomab is a bispecific T cell-engaging antibody approved for treatment of relapsed/refractory (r/r) ALL, with 40%-50% complete response (CR)/CR with incomplete count recovery (CRi). Cytokine release syndrome (CRS) as a major adverse effect after blinatumomab therapy. Here, we evaluated the possible association between single-nucleotide polymorphisms (SNPs) in cytokine genes, disease response, and CRS in r/r ALL patients who received blinatumomab between 2012 and 2017 at our center (n = 66), using patients' archived DNA samples. With a median duration of 9.5 months (range: 1-37), 37 patients (56.1%) achieved CR/CRi, 54 (81.8%) experienced CRS (G1: n = 35, G2: n = 14, G3: n = 5), and 9 (13.6%) developed neurotoxicity. By multivariable analysis, after adjusting for high disease burden, one SNP on IL2 (rs2069762), odds ratio (OR) = 0.074 (95% CI: NE-0.43, P = .01) and one SNP on IL17A (rs4711998), OR = 0.28 (95% CI: 0.078-0.92, P = .034) were independently associated with CR/CRi. None of the analyzed SNPs were associated with CRS. To our knowledge, this is the first study demonstrating a possible association between treatment response to blinatumomab and SNPs. Our hypothesis-generated data suggest a potential role for IL-17 and IL-2 in blinatumomab response and justify a larger confirmatory study, which may lead to personalized blinatumomab immunotherapy for B-ALL.

Purpose This analysis evaluated the relationship between concentrations of quizartinib and its active metabolite AC886 and QT interval corrected using Fridericia’s formula (QTcF) in patients with relapsed/refractory acute myeloid leukemia (AML) treated in the phase 3 QuANTUM-R study (NCT02039726). Methods The analysis dataset included 226 patients with AML. Quizartinib dihydrochloride was administered as daily doses of 20, 30, and 60 mg. Nonlinear mixed-effects modeling was performed using observed quizartinib and AC886 concentrations and time-matched mean electrocardiogram measurements. Results Observed QTcF increased with quizartinib and AC886 concentrations; the relationship was best described by a nonlinear maximum effect (Emax) model. The predicted mean increase in QTcF at the maximum concentration of quizartinib and AC886 associated with 60 mg/day was 21.1 ms (90% CI, 18.3–23.6 ms). Age, body weight, sex, race, baseline QTcF, QT-prolonging drug use, hypomagnesemia, and hypocalcemia were not significant predictors of QTcF. Hypokalemia (serum potassium Conclusion QTcF increase was dependent on quizartinib and AC886 concentrations, but patient factors, including sex and age, did not affect the concentration–QTcF relationship. Because concomitant strong cytochrome P450 3A (CYP3A) inhibitor use significantly increases quizartinib concentration, these results support the clinical recommendation of quizartinib dose reduction in patients concurrently receiving a strong CYP3A inhibitor. Clinical Trial Registration NCT02039726 (registered January 20, 2014).

The combination of hypomethylating agents with the selective Bcl-2 inhibitor venetoclax (HMA-VEN) has emerged as a highly active regimen in patients with acute myelogenous leukemia (AML) in both the upfront and relapsed/refractory (r/r) settings. We report our early experience with a cohort of patients who were able to proceed to allogeneic hematopoietic cell transplantation (alloHCT) after HMA-VEN therapy. Thirty-two patients with AML (19 r/r and 13 de novo) with a median age of 62 years underwent alloHCT after HMA-VEN therapy. Twenty-two (68.8%) were in complete remission (CR)/CR with incomplete count recovery at time of HCT. With a median follow up of 14.4 months, the 1-year overall survival (OS) was 62.5%, and disease-free survival was 43.8%. The 1-year nonrelapse mortality rate was 18.8%, and the cumulative incidence of relapse was 37.5%. Among patients who underwent alloHCT in CR, the 1-year OS was 77.3%, and the cumulative incidence of nonrelapse mortality was 9.1%. The cumulative incidence of grade II-IV acute graft-versus-host disease was 43.8%. We conclude that alloHCT after HMA-VEN is therapy associated with favorable allogeneic HCT outcomes in newly diagnosed older patients with AML, as well as those with r/r AML.

Aberrant DNA methylation often silences transcription of tumor-suppressor genes and is considered a hallmark of myeloid neoplasms. Similarly, histone deacetylation represses transcription of genes responsible for cell differentiation/death. A previous clinical study suggested potential pharmacodynamic antagonism between histone deacetylase inhibitors (HDACi) and DNA hypomethylating agents (HMA). Herein, to determine such antagonism, we used MDS/AML lines and NHD13 transgenic mice, and demonstrated that treatment with the pan-HDACi suberoylanilide hydroxamic acid (SAHA) significantly decreased TET2 expression and global 5-hydroxymethylcytosine (5hmC) levels. Mechanistically, our RNAi screen revealed that HDAC4 was responsible for maintaining TET2 levels. Accordingly, HDAC4 knockout reduced expression levels of MTSS1, a known TET2 target, an event associated with decreased 5hmC enrichment on the MTSS1 enhancer. Retrospective analysis of GEO datasets demonstrated that lower HDAC4 levels predict worse prognosis for AML patients. In an MDS-L xenografted immunodeficient mouse model, vitamin C co-treatment prevented TET2 loss of activity seen following SAHA treatment. Accordingly, vitamin C co-treatment further reduced MDS-L cell engraftment relative to SAHA alone. In summary, our findings suggest that co-administration of a TET2 agonist with pan-HDACi treatment could effectively counter potential diminution in TET2 activity resulting from pan-HDACi treatment alone, providing a rationale for evaluating such combinations against high-risk MDS/AML.

FMS-like tyrosine kinase 3 (FLT3) mutations are prevalent in acute myeloid leukemia (AML), and their presence confers adverse risk. FLT3-mutated (FLT3m) AML is a challenging leukemia to manage, particularly in older and unfit patients as well as patients with relapsed/refractory (r/r) disease. We retrospectively analyzed the outcomes of 50 FLT3m AML patients (17 treatment-naïve, 33 r/r) treated with venetoclax (VEN) and hypomethylating agents (HMA). The overall CR/CRi rate with VEN-HMA was 60% (94% in treatment-naïve AML and 42% in r/r AML). Early (60-days) treatment related mortality was 2%. The r/r AML setting was an independent predictor of lower complete response (OR: 0.08; 95%CI: 0.00-0.60, P = .03). Cytogenetics-molecular risk, concurrent mutations, the type of FLT3 mutation (ITD vs TKD), the ITD allelic ratio, the type of HMA, age, prior exposure to HMA and receipt of prior allogeneic transplant did not independently impact response or leukemia-free survival (LFS). Concurrent IDH mutations were associated with lower CR/CRi (P = .01), while ASXL1 or TET2 mutations showed a non-significant association toward higher CR/CRi (P = .07, for both). However, none of the concurrent mutations were an independent predictor for response when adjusted to AML setting. In conclusion, VEN-HMA is associated with encouraging efficacy in FLT3m AML among both newly diagnosed unfit and r/r patients.

Quizartinib is an FMS‐like tyrosine kinase 3 (FLT3) inhibitor that has shown robust clinical activity in patients with FLT3‐internal tandem duplication–mutated relapsed/refractory acute myeloid leukemia (AML). This analysis evaluated the population pharmacokinetics (PK) of quizartinib and its active metabolite, AC886, in a pooled analysis of data from 649 healthy volunteers or patients with AML from 8 clinical trials including the phase 3 QuANTUM‐R study. Quizartinib was given as a single dose or multiple once‐daily doses of 20, 30, 60, or 90 mg. Nonlinear mixed‐effects modeling was performed using observed concentrations of quizartinib and AC886. Strong CYP3A inhibitor use resulted in an 82% increase in the area under the curve (AUC) and a 72% increase in the maximum concentration (Cmax) of quizartinib. Albumin level, age, and body surface area were statistically significant covariates on quizartinib PK. However, their individual effects on quizartinib AUC and Cmax were

The combination of venetoclax with hypomethylating agents (VEN-HMAs) showed promising activity in newly diagnosed and relapsed/refractory (r/r) acute myeloid leukemia (AML). Treatment with VEN-HMAs results in prolonged cytopenia, thereby exposing patients to invasive fungal infections (IFIs). Here, we retrospectively studied a cohort of 119 AML patients treated with VEN-HMAs and analyzed the occurrence of IFIs, as well as our practice of antifungal prophylaxis, with the aim to identify the nature and risk factors for IFIs and their association with the type of antifungal prophylaxis used. The intended antifungal prophylaxis was micafungin in 38% of patients, azoles in 41% of patients, and none in 21% of patients. Older age was associated with no antifungal prophylaxis or micafungin use and lesser use of azoles (P = .043). We recorded 15 (12.6%) patients who developed probable or proven IFIs, with a median onset of 72 days (range, 35-281) after starting therapy. IFIs were more common among nonresponders compared with responders to VEN-HMA therapy (22% vs 6%, P = .0132) and in r/r compared with newly diagnosed AML (19% vs 5%, P = .0498); however, the antifungal prophylaxis used, patient age, hypomethylating agent schedule, history of prior allogeneic transplant, and initial neutropenia duration did not influence the development of IFIs during therapy. We conclude that the overall risk of IFIs during VEN-HMA therapy is low. The risk of IFIs is higher in nonresponders and in those who were treated in the r/r setting; these patients need reevaluation of their antifungal prophylaxis to minimize the risk of IFIs during therapy.

Background: CTLA-4 blockade with ipilimumab (IPI) has modest activity in hematologic malignancies relapsed post allogeneic hematopoietic cell transplantation (allo-HCT) (Davids M, NEJM). Adding decitabine (DAC) to IPI may increase efficacy of this approach in myelodysplastic syndromes (MDS)/acute myeloid leukemia (AML), and we further asked the extent to which alloreactivity contributed to this activity. Here, we present safety (Table 1) and clinical activity (Figure 1) from a phase I, multicenter, investigator-initiated study (CTEP 10026) of DAC plus IPI in pts with R/R MDS/AML with (Arm A) and without (Arm B) prior HCT. Methods: Pts ≥ 18 y with R/R MDS (≥ 5% blasts), R/R AML or untreated secondary AML were eligible. Prior HMA was permitted but trial was later amended to exclude those with disease progression on HMA therapy within 12 weeks of study entry. Pts post allo-HCT (Arm A) were required to be > 3 mo from donor cell infusion, have no prior acute GVHD Gr III or higher, be > 2 weeks off of immunosuppression and have donor T-cell chimerism ≥ 20%. Treatment was given in 28-day cycles with a lead-in single agent DAC (cycle 0) followed by combination DAC + IPI for up to a year. DAC infusion was given at 20 mg/m2 days 1-5. IPI infusion was given at 3 mg/kg (DL0), 5 mg/kg (DL1) or 10 mg/kg (DL2) on day 1 of cycles 1-4, 5, 7, 9 and 11. DLT was defined as ≥ Gr 3 non-hematologic adverse event (AE), acute GVHD, and steroid-refractory immune-related AE within 8 weeks of first IPI dose. Results: At data cut-off, 32 of 39 enrolled pts received at least 1 dose of DAC+IPI; 4 of 7 did not move on to C1D1 due to AML-related complications. Median age was 72 y (range 29-85); 25 had AML and 7 had MDS. Median number of prior regimens was 2 (range, 0-5). Twenty of 32 pts had received prior HMA therapy. A median of 3 IPI doses were given (range, 1-8). NGS performed on screening marrows using an 88-gene panel revealed mutations most commonly in ASXL1 (n=9), RUNX1 and STAG2 (n=6 each), and DNMT3A, NRAS and TP53 (n=5 each). Arm A (Post allo-HCT): Sixteen pts received DAC+IPI across the 3 DLs (7 at DL0, 3 at DL1, 6 at DL2; dose-expansion is open at DL2). The most common treatment emergent Gr 3/4 AEs were febrile neutropenia (n=3) and AST elevation, lymphocytopenia, neutropenia, thrombocytopenia, leukopenia (n=2 each). Seven of 16 pts experienced immune-related AE, including 1 with late-onset acute GVHD Gr III (colon/liver), 4 with chronic GVHD (mild, n=2; moderate, n=1; severe n=1), and 2 with Gr 2/3 ipi-induced colitis. All immune-related AEs were reversible with steroids, except for one case of steroid refractory Gr III acute GVHD complicated by fatal septic shock (DLT at IPI 10 mg/kg). In total, 4 of 16 evaluable pts achieved response, including 3 with CR and 1 with marrow CR; 2 of 4 responders had immune-related AE. For these 16 pts, the median OS is 12.8 mo (95% CI: 7.6-NA). Arm B (transplant-naïve): Sixteen pts received DAC+IPI across the 3 DLs (4 at DL0, 3 at DL1, 6 at DL2; 3 are in dose-expansion at DL2). The most common treatment emergent Gr 3/4 AEs were lymphocytopenia, thrombocytopenia and leukopenia (n=5 each); neutropenia (n=4); and anemia, fatigue, lung infection, and febrile neutropenia (n=3 each). In 6 of 16 pts that had ≥ Gr 2 immune-related AEs, all were reversible with steroids (including Gr 3 colitis (n=1), Gr 3 dermatitis (n=2), Gr 2 pneumonitis (n=1), Gr 3 hypophysitis/Gr 2 arthritis (n=1)), except for a case of Gr 2 dermatitis (resolved)/Gr 4 immune thrombocytopenia (refractory to steroids, transfusions and IVIG) (n=1; DLT at IPI 10 mg/kg). No study treatment-related deaths were observed. Objective responses were detected in 8 of 16 evaluable pts with 3 CR, 2 CRi, and 3 marrow CR. Only 2 of 8 responders had immune-related AEs. For these 16 pts, the median OS is 18.3 mo (95% CI: 11.7-NA). Overall, 2 pts discontinued study treatment due to AE. Dose expansion continues at DL2 (MTD) in Arm A and Arm B to further establish safety and tolerability. Correlative science including immunophenotyping is ongoing and will be presented. Conclusion: In this ongoing phase 1 study in pts with R/R or secondary MDS/AML, DAC plus IPI had expected AE profile and exhibited encouraging clinical activity. The rate of immune-related toxicity was frequent but similar to prior observations with IPI 10 mg/kg for melanoma. Further, high clinical activity was observed amongst pts who did not receive allo-HCT, suggesting that an alloreactive environment may not be required to benefit from CTLA-4 blockade. Disclosures Garcia: Pfizer: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Eli Lily: Research Funding. Brunner:Astra Zeneca: Research Funding; Janssen: Research Funding; Xcenda: Consultancy; GSK: Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Jazz Pharma: Consultancy; Forty Seven, Inc: Consultancy; Celgene/BMS: Consultancy, Research Funding; Biogen: Consultancy; Acceleron Pharma Inc.: Consultancy. Neuberg:Celgene: Research Funding; Madrigal Pharmaceuticals: Current equity holder in publicly-traded company; Pharmacyclics: Research Funding. Steensma:Takeda: Consultancy; BMS/Celgene: Consultancy; Onconova: Consultancy; Arena: Current equity holder in publicly-traded company; CRISPR: Current equity holder in publicly-traded company; Aprea Therapeutics: Research Funding; Arrowhead Pharmaceuticals: Current equity holder in publicly-traded company; Astex Pharmaceuticals, Onconova Therapeutics, Pfizer, Stemline Therapeutics, Summer Road: Consultancy; H3 Biosciences: Research Funding. Rodig:Bristol Myers Squibb: Research Funding; Merck: Research Funding; Affimed: Research Funding; KITE/Gilead: Research Funding; Immunitas: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Lindsley:Takeda Pharmaceuticals: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding; Bluebird Bio: Consultancy; MedImmune: Research Funding. Davids:Research to Practice: Honoraria; Eli Lilly: Consultancy; Adaptive Biotechnologies: Consultancy; Novartis: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Merck: Consultancy; Gilead Sciences: Consultancy; Surface Oncology: Research Funding; MEI Pharma: Consultancy, Research Funding; Bristol Myers Squibb: Research Funding; Ascentage Pharma: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Sunesis: Consultancy; Zentalis: Consultancy; Syros Pharmaceuticals: Consultancy; Janssen: Consultancy; BeiGene: Consultancy; Celgene: Consultancy; Genentech: Consultancy, Research Funding; AbbVie: Consultancy; TG Therapeutics: Consultancy, Research Funding; Verastem: Consultancy, Research Funding. Wu:BionTech: Current equity holder in publicly-traded company; Pharmacyclics: Research Funding. Stone:Pfizer: Consultancy; Syros: Consultancy; Stemline: Consultancy; Actinium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gemoab: Consultancy; Syndax: Consultancy, Research Funding; Macrogenics: Consultancy; Trovagene: Consultancy; Biolinerx: Consultancy; Argenix: Other; Jazz: Consultancy; Aztra-Zeneca: Consultancy; Daiichi-Sankyo: Consultancy; Astellas: Consultancy; Syntrix: Other: DSMB; Novartis: Consultancy, Research Funding; Takeda: Other: DSMB; Arog: Consultancy, Research Funding; Agios: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Janssen: Consultancy; Celgene: Consultancy, Other. DeAngelo:Takeda: Consultancy; Blueprint Medicines Corporation: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Incyte Corporation: Consultancy; Abbvie: Research Funding; Glycomimetics: Research Funding; Shire: Consultancy; Autolos: Consultancy; Amgen: Consultancy; Agios: Consultancy; Pfizer: Consultancy; Forty-Seven: Consultancy; Jazz: Consultancy. Soiffer:Rheos Therapeutics: Consultancy; Celgene: Other; Juno: Other; Alexion: Consultancy; Novartis: Consultancy; VOR Biopharma: Consultancy; Mana Therapeutics: Consultancy; Precision Bioscience: Consultancy; Cugene: Consultancy; Gilead: Consultancy; Be The Match/National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: Decitabine plus Ipilimumab to be given in the context of a clinical trial

Efficacy of PTCy after mismatched unrelated donor (MMUD) HCT is unknown. In this pilot clinical trial, we enrolled 38 patients with hematologic malignancies scheduled to undergo MMUD-HCT (≥6/8 HLA-matched donors) onto 1 of 2 conditioning strata: myeloablative using fludarabine and fractionated total body irradiation (n = 19) or reduced intensity with fludarabine/melphalan (n = 19). Graft source was peripheral blood stem cells (PBSCs), and GVHD prophylaxis was PTCy, tacrolimus, and mycophenolate mofetil. Patients’ median age was 53 years (range, 21-72 years). Median number of HLA mismatches was 2 (range, 1-4) of 12 loci. Twenty-three patients (61%) were considered racial (n = 12) or ethnic (n = 11) minorities. Median time to neutrophil engraftment was 16 days (range, 13-35 days). With a median follow-up of 18.3 months (range, 4.3-25.0 months) for surviving patients, 1-year overall survival (OS) and GVHD-free/relapse-free survival (GRFS) were 87% (95% confidence interval [CI]: 71-94) and 68% (95% CI: 51-81), respectively. Cumulative incidence of nonrelapse mortality at 100 days and 1 year were 0% and 11% (95% CI: 4-27), respectively, whereas relapse/progression was 11% (95% CI: 4-27). Cumulative incidence of 100-day acute GVHD grades 2-4 and 3-4 and 1-year chronic GVHD were 50% (95% CI: 36-69), 18% (95% CI: 9-36), and 48% (95% CI: 34-68), respectively. The rate of moderate/severe chronic GVHD was 3% in the entire cohort. We showed highly promising OS/GRFS rates with an acceptable risk profile after PBSC-MMUD-HCT with PTCy. This trial was registered at www.clinicaltrials.gov as #NCT03128359.

Background Mutations in isocitrate dehydrogenase (IDH)1/2 genes result in nicotinamide adenine dinucleotide phosphate-dependent reduction of α-ketoglutarate and formation of 2-hydroxyglutarate, which blocks normal cellular differentiation and promotes leukemogenesis. Nearly 20% of acute myeloid leukemia (AML) patients carry IDH1/2 mutations. Although multiple investigators have described the prognostic implications of IDH mutations in AML patients receiving chemotherapy, the effect of these mutations on outcomes after allogeneic (allo) hematopoietic cell transplantation (HCT) is unknown. Patients and Methods We report on the clinical outcome of a cohort of AML patients, who were tested for IDH mutations and underwent alloHCT at City of Hope (2015-2017). Of a total of 317 screened patients, 99 (31%) underwent alloHCT, of whom 23 carried and 76 did not carry IDH mutations (control). Results No statistical significance was detected in patient’s overall survival (P = .84). With a median follow-up of 7.8 months, 1-year relapse rate of 29% and 13% was seen in the IDH-mutated and control group, respectively (P = .033). IDH1/2 mutation status remained significantly associated with relapse (hazard ratio, 2.8; P = .046) after inclusion of pre-HCT disease status in a multivariable model. Conclusion Our results, despite low patient numbers, indicate that IDH mutations are associated with higher relapse rate after alloHCT. Further prospective studies on post transplantation IDH inhibition is required to improve outcomes in AML patients who carry IDH mutations.

Pracinostat, a potent oral pan-histone deacetylase inhibitor with modest single-agent activity in acute myeloid leukemia (AML), has shown synergistic antitumor activity when combined with azacitidine. This single-group, multicenter phase 2 study assessed the safety and efficacy of pracinostat combined with azacitidine in patients who were at least 65 years old with newly diagnosed AML and who were ineligible for standard induction chemotherapy. Patients received pracinostat 60 mg/d, 3 d/wk, for 3 consecutive weeks, plus azacitidine 75 mg/m2 daily for 7 days in a 28-day cycle. Primary endpoints were complete remission (CR), CR with incomplete count recovery (CRi), and morphologic leukemia-free state (MLFS) rates of the combination. Secondary endpoints included safety, progression-free survival (PFS), and overall survival (OS) of the regimen. Fifty patients (33 de novo, 12 secondary, and 5 therapy-related AML) were enrolled. Twenty-six patients (52%) achieved the primary endpoint of CR (42%), CRi (4%), and MLFS (6%). Median OS and PFS were 19.1 months (95% confidence interval [CI], 10-26.5 months) and 12.6 months (95% CI, 10-17.7 months), respectively, with a 1-year OS rate of 62%. Forty-three patients (86%) experienced at least 1 grade 3 or worse treatment-emergent adverse event with the combination, with infections (52%), thrombocytopenia (46%), and febrile neutropenia (44%) reported as the most common toxicities. The 30- and 60-day all-cause mortality rates were 2% and 10%, respectively. DNA sequencing revealed somatic mutations at baseline, and clearance rates correlated with response to treatment. Pracinostat plus azacitidine is a well-tolerated and active regimen in the frontline treatment of older patients with AML unfit for intensive therapy. A larger controlled trial is ongoing. This trial was registered at www.clinicaltrials.gov as #NCT01912274.

Although allogeneic hematopoietic cell transplantation (allo-HCT) is the only curative treatment for myelofibrosis (MF), data are limited on how molecular markers predict transplantation outcomes. We retrospectively evaluated transplantation outcomes of 110 consecutive MF patients who underwent allo-HCT with a fludarabine/melphalan (Flu/Mel) conditioning regimen at our center and assessed the impact of molecular markers on outcomes based on a 72-gene next-generation sequencing panel and Mutation-Enhanced International Prognostic Scoring System 70+ v2.0 (MIPSS70+ v2.0). With a median follow-up of 63.7 months, the 5-year overall survival (OS) rate was 65% and the nonrelapse mortality (NRM) rate was 17%. In mutational analysis, JAK2 V617F and ASXL1 mutations were the most common. By univariable analysis, higher Dynamic International Prognostic Scoring System scores, unrelated donor type, and very-high-risk cytogenetics were significantly associated with lower OS. Only CBL mutations were significantly associated with lower OS (hazard ratio [HR], 2.64; P = .032) and increased NRM (HR, 3.68; P = .004) after allo-HCT, but CALR, ASXL1, and IDH mutations did not have an impact on transplantation outcomes. Patient classification per MIPSS70 showed worse OS for high-risk (HR, 0.49; P = .039) compared with intermediate-risk patients. Classification per MIPSS70+ v2.0 demonstrated better OS when intermediate-risk patients were compared with high-risk patients (HR, 0.291) and much lower OS when very-high-risk patients were compared with high-risk patients (HR, 5.05; P ≤ .001). In summary, we present one of the largest single-center experiences of Flu/Mel-based allo-HCT, demonstrating that revised cytogenetic changes and MIPSS70+ v2.0 score predict transplantation outcomes, and thus can better inform physicians and patients in making decisions about allo-HCT.

Myelodysplastic syndrome (MDS) is a heterogeneous hematological neoplasm with a wide range of clinical presentations from isolated anemia to pancytopenia and propensity to transform to acute myeloid leukemia. MDS is characterized by morphologic bone marrow dysplasia and ineffective hematopoiesis resulting from a range of cytogenetic abnormalities and somatic gene mutations. Disease management varies from observation alone for low-risk disease to hypomethylating agents and hematopoietic cell transplantation (HCT) for higher risk disease. In this chapter, we review the classification, risk stratification, and optimal management of patients with MDS.

We report here on a novel pro-leukemogenic role of FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) that interferes with microRNAs (miRNAs) biogenesis in acute myeloid leukemia (AML) blasts. We showed that FLT3-ITD interferes with the canonical biogenesis of intron-hosted miRNAs such as miR-126, by phosphorylating SPRED1 protein and inhibiting the "gatekeeper" Exportin 5 (XPO5)/RAN-GTP complex that regulates the nucleus-to-cytoplasm transport of pre-miRNAs for completion of maturation into mature miRNAs. Of note, despite the blockage of "canonical" miRNA biogenesis, miR-155 remains upregulated in FLT3-ITD+ AML blasts, suggesting activation of alternative mechanisms of miRNA biogenesis that circumvent the XPO5/RAN-GTP blockage. MiR-155, a BIC-155 long noncoding (lnc) RNA-hosted oncogenic miRNA, has previously been implicated in FLT3-ITD+ AML blast hyperproliferation. We showed that FLT3-ITD upregulates miR-155 by inhibiting DDX3X, a protein implicated in the splicing of lncRNAs, via p-AKT. Inhibition of DDX3X increases unspliced BIC-155 that is then shuttled by NXF1 from the nucleus to the cytoplasm, where it is processed into mature miR-155 by cytoplasmic DROSHA, thereby bypassing the XPO5/RAN-GTP blockage via "non-canonical" mechanisms of miRNA biogenesis.

Introduction of novel salvage therapies and expansion of the donor pool within the past decade have allowed more patients with relapsed/refractory (r/r) B cell acute lymphoblastic leukemia (B-ALL) to receive allogeneic hematopoietic cell transplantation (alloHCT). The impact of each salvage therapy on transplant outcomes have not been compared. Our primary objective was to determine post-HCT relapse-free survival (RFS) in adult patients with r/r Philadelphia-chromosome negative (Phneg) B-ALL. We retrospectively studied alloHCT outcomes in 108 adult patients with r/r Phneg B-ALL transplanted in morphological remission achieved by salvage therapy. Salvage therapies were chemotherapy-based combination (n = 45, 42%), blinatumomab (n=43, 40%), inotuzumab (n = 14, 13%), or CAR T cells (n = 6, 6%). The 2-year RFS and overall survival (OS) were 44% and 50%, respectively. In multivariable analysis, conditioning with reduced-intensity or non-myeloablative regimens (hazard ratio [HR] = 2.23, 95% confidence interval [CI], 1.31-3.80; P = .003), having received ≥3 lines of therapies prior to transplant (HR = 2.66, 95% CI, 1.56-4.54; P

Despite the substantial clinical activity of fms-related tyrosine kinase 3 (FLT3) inhibitors in relapsed or refractory (R/R) FLT3-ITD‒positive acute myelogenous leukemia (AML), durable remissions and prolonged survival in this population require allogeneic hematopoietic stem cell transplantation (allo-HSCT). Quizartinib, a once-daily oral, highly potent, and selective FLT3 inhibitor, significantly prolonged overall survival (OS) and improved clinical benefit compared with salvage chemotherapy (median OS, 6.2 months versus 4.7 months; hazard ratio [HR], .76; 95% confidence interval [CI], .58 to .98; P = .018; composite complete remission [CRc] rate, 48% versus 27%; median duration of CRc, 2.8 months versus 1.2 months; mortality rate, .8% versus 14% by day 30, 7% versus 24% by day 60) in patients with R/R FLT3-ITD AML in the phase 3 QuANTUM-R trial. In this post hoc analysis, we described the characteristics of and clinical outcomes in patients who underwent on-study HSCT in QuANTUM-R at the investigator's discretion and institutional practices. Of 367 randomized patients, 78 (32%) in the quizartinib arm and 14 (11%) in the salvage chemotherapy arm underwent on-study allo-HSCT without any intervening therapy for AML after quizartinib or study-specified salvage chemotherapy. Pooled data of patients from both treatment arms showed a longer median overall survival (OS) in transplant recipients versus those treated without allo-HSCT (12.2 months versus 4.4 months; HR, .315; 95% CI, .233 to .427). Pooled data also showed a longer median OS in patients with a last recorded response of CRc before allo-HSCT versus patients without a CRc (20.1 months versus 8.8 months; HR, .506; 95% CI, .296 to .864). By treatment arm, the median OS was 25.1 months with quizartinib and 20.1 months with salvage chemotherapy in patients with a last recorded response of CRc before allo-HSCT. Forty-eight patients in the quizartinib arm continued quizartinib treatment after allo-HSCT. In the 31 patients with a last recorded response of CRc before allo-HSCT who continued quizartinib after allo-HSCT, the median OS was 27.1 months. Continuation of quizartinib after allo-HSCT was tolerable, and no new safety signals were identified. These results suggest that post-transplantation survival following salvage chemotherapy and quizartinib treatment are similar. However, quizartinib response occurs more frequently than with salvage chemotherapy, potentially allowing more patients to undergo transplantation and achieve durable clinical benefit. In addition, post-transplant quizartinib was found to be tolerable and may be associated with prolonged survival in some patients, highlighting its potential value in the management of patients with FLT3-ITD R/R AML.

Acute lymphoblastic leukemia (ALL) is associated with poor survival in older adults, and allogeneic hematopoietic cell transplant (HCT) with reduced-intensity conditioning (RIC) has been an increasingly used strategy in this population. At City of Hope we conducted a retrospective analysis of 72 patients who underwent allogeneic HCT with fludarabine and melphalan (FluMel) as the conditioning regimen between 2005 and 2018, from either a matched sibling or fully matched unrelated donor while in complete remission. Tacrolimus and sirolimus (T/S) were used as graft-versus-host disease (GVHD) prophylaxis. Overall survival and progression-free survival at 4 years post-HCT were 58% and 44%, respectively. The cumulative incidences of relapse/progression and nonrelapse mortality at 4 years were 34% and 22%, respectively. Patients with Philadelphia chromosome–positive (Ph+) ALL had a significantly lower cumulative incidence of relapse/progression (20% versus 48% for patients with Ph-negative status, P = .007). In conclusion, RIC HCT with FluMel conditioning and T/S GVHD prophylaxis was associated with favorable outcomes in patients with Ph+ ALL and should be considered as a viable consolidative therapy for adult patients with ALL.

Chimeric antigen receptor T cell therapy is gaining clinical use in the management of B cell lymphomas. As the use of this unique treatment option increases, its associated toxicities will require recognition and treatment. In this review, we aim to discuss the cardiovascular toxicities of chimeric antigen receptor T cell therapy and our approach to their clinical management. Cardiotoxicity may be due to direct or indirect effects of infused chimeric antigen receptor T cells. The cytokine release syndrome has been described extensively in the literature. Studies have also reported cardiovascular dysfunction including hypotension, left ventricular dysfunction, heart failure, and cardiogenic shock in the setting of cytokine release syndrome. While there are no standardized guidelines for the treatment of cytokine release syndrome or associated cardiotoxicity, we present our current clinical practices. Further research is indicated into the pathophysiology of therapy-associated cardiac dysfunction and effective management strategies to optimize patient outcomes.

Historically, outcomes of adult patients with relapsed acute lymphoblastic leukemia (ALL) who fail to enter remission with conventional chemotherapy are very poor. Blinatumomab, a bispecific CD3/CD19 antibody, has shown remarkable activity in relapsed/refractory (r/r) ALL. Although allogeneic hematopoietic cell transplant (HCT) is the recommended consolidation therapy for patients with r/r ALL who respond to salvage therapy, HCT and toxicity outcomes for those who received blinatumomab salvage and HCT remain largely unknown. We treated 89 patients with r/r ALL with blinatumomab, of whom 43 patients (48%) achieved remission. Here we describe our single-center experience in the subset of patients who responded to blinatumomab salvage therapy for eradication of either gross (n = 24) or minimal residual disease (n = 11) before HCT. Overall survival at 1 and 2 years after allogeneic HCT was 77% and 52%, respectively. Leukemia-free survival at 1 and 2 years were 65% and 40%, respectively. Additionally, with blinatumomab administration pre-HCT, no unusual toxicities such as delayed neutrophil/platelet engraftment or graft failure were observed. Acute grades II to IV graft-versus-host disease (GVHD) at day +100 post-HCT was at 43% and 2-year chronic GVHD was 36%, both comparable with historic control subjects. Finally, results of our subset analysis based on pre-HCT minimal residual disease (MRD) status indicated no significant difference in survival outcomes among patients undergoing transplant in MRD-negative status and the entire cohort. In conclusion, based on results of this study, blinatumomab may be considered as a safe and effective agent for r/r ALL patients before HCT.

Therapy-related acute lymphoblastic leukemia remains poorly defined due to a lack of large data sets recognizing the defining characteristics of this entity. We reviewed all consecutive cases of adult acute lymphoblastic leukemia treated at our institution between 2000 and 2017 and identified therapy-related cases - defined as acute lymphoblastic leukemia preceded by prior exposure to cytotoxic chemotherapy and/or radiation. Of 1022 patients with acute lymphoblastic leukemia, 93 (9.1%) were classified as therapy-related. The median latency for therapy-related acute lymphoblastic leukemia onset was 6.8 years from original diagnosis, and this was shorter for patients carrying the MLL gene rearrangement compared to those with other cytogenetics. When compared to de novo acute lymphoblastic leukemia, therapy-related patients were older (P

Paroxysmal nocturnal hemoglobinuria (PNH) is frequently seen in the context of other aplastic anemia and myelodysplastic syndromes and is associated with hemolysis and increased thromboembolic events. Allogeneic hematopoietic stem cell transplantation (alloHCT) is the sole curative treatment but is associated with significant morbidity. The terminal complement inhibitor eculizumab reduces hemolysis and thromboembolic events and is the sole Food and Drug Administration-approved therapy for PNH. Prophylactic administration of this agent in the early post-transplantation setting to prevent hemolysis and thrombosis has not been described in the literature. We describe our institutional experience of 8 patients with PNH who underwent alloHCT and who received at least 1 dose of eculizumab within 30 days of alloHCT for prevention of thrombosis and hemolysis. One patient with underlying aplastic anemia who received bone marrow stem cells failed to engraft. Another patient experienced steroid-refractory grade IV acute graft-versus-host disease and died of a fungal infection. The other patients engrafted well; no hemolysis, thrombotic events, or infections associated with encapsulated bacteria occurred in any of the 8 patients.

Myelodysplastic syndromes (MDS) frequently progresses to acute myeloid leukemia (AML). Mechanisms underlying MDS transformation remain unclear. We showed that TET2 deficiency enhances MDS maintenance (PMID: 30146412). Besides frequent mutated in MDS/AML, TET2 levels were decreased during MDS progression (PMID: 23827711). Recently, we analyzed a dataset (GSE19429) and found lower TET2 levels correlated with shortened survival of patients with high-risk MDS. We thus assessed TET2 function in MDS leukemia transformation by deleting TET2 in a NHD13 knock-in mouse model, in which ~30% of mice develop AML. Therefore, we crossed conditional TET2-KO mice with NHD13 transgenic mice. NHD13/TET2-KO (NT) mice developed leukemia with shorter survival than did NHD13/TET2-WT (ctrl) mice (median days, NT: 219 vs. ctrl: 366, n=12, p2) in NT mice and ranked them based on their association with AML prognosis using PRECOG (http://precog.stanford.edu). We selected top three candidates SETD2, ARIH2, TET3 for further analysis. ChIP-qPCR revealed increased 5hmC modification at the mutant loci of these genes, consistent with a finding that the genomic regions with increased 5hmC modification are more subjective to occur mutations (PMID: 28440315). TET3 and SETD2, as tumor suppressors, exhibit frameshift-deletion. ARIH2 represents a single-nucleotide variant (ARIH2K440N). To test if ARIH2 loss-of-function accelerates proliferation, we transduced NHD13 c-kit+ cells with shARIH2 and performed CFC analysis. ARIH2 knockdown increased colony number relative to ctrl (shARIH2: 163±3.7 vs. shCtrl: 95±1.7, n=3, p Citation Format: Feiteng Huang, Jie Sun, Wei Chen, Lei Zhang, Xin He, Haojie Dong, Yuhui Wu, Hanying Wang, Zheng Li, Victor Huang, Samer Khaled, Ling Li. TET2 deficiency accelerates leukemogenesis in the NHD13 mouse model of MDS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2934.

Background: Allogeneic hematopoietic cell transplantation (alloHCT) is the approach that offers the highest curative rate for acute myelogenous leukemia (AML) with intermediate or high-risk cytogenetics. Graft versus host disease (GvHD) has remained the main cause of post-transplantation mortality and morbidity, despite advances in prophylaxis and therapy, adding significant economic burden and affecting quality of life. It would be desirable to reduce the rate of GvHD among patients in complete remission (CR) without increasing the risk of relapse. In this study, we have developed a novel conditioning regimen of total marrow and lymphoid irradiation (TMLI) at 2000 cGy, together with post-transplant cyclophosphamide (PTCy), to 1) reduce the possibly increased risk of relapse from PTCy, by using escalated radiation doses of TMLI, as increasing radiation doses has the potential to decrease the post-transplantation relapse rate (Blood, vol 76, pp. 1867-1871, 1990); and 2) reduce the risk of chronic GvHD by using PTCy. The major goal of this pilot study of TMLI and PTCy (clinicaltrials.gov: NCT03467386), was to thus improve GvHD-free/relapse-free survival (GRFS), reported to be 45% from total body irradiation (TBI) and tacrolimus/sirolimus prophylaxis (BBMT, vol 26(2), pp. 292-299, 2020), in patients with AML in remission. Patients and Methods: A total of 18 patients were enrolled and treated (see Table) between March 2018 and December 2019. Key criteria were ages 18 to 60, first or second CR, minimal residual disease negative by multi-color flow cytometry, and normal organ function. TMLI was administered on days -4 to 0 without addition of chemotherapy. The radiation dose for all patients (n=18) was 2000 cGy, delivered in 200 cGy fractions twice daily. The radiation dose delivered to the liver and brain was kept at 1200 cGy. Remaining organs were considered non-targeted. All patients received peripheral blood stem cells on day 0. Cyclophosphamide was given on days +3 and +4, 50 mg/kg each day for GVHD prevention. Tacrolimus, 1 mg continuous infusion adjusted to maintain levels from 5 to 10 ng/mL was given from day +5 to day +90, and G-CSF 5 µg/kg daily was administered at day +5 until recovery of neutrophil counts. Endpoints included toxicity, GRFS at 1 year, engraftment, overall survival (OS), and non-relapse mortality (NRM). Toxicities were defined according to the Bearman and CTCAE 4.03 scales, the latter for hematologic toxicity. A patient safety lead-in segment (n=6) was conducted to ensure that there were no unexpected toxicities, allowing for a dose de-escalation to 1800 cGy. GRFS was defined as grade 3-4 acute GvHD, chronic GvHD requiring systemic treatment, relapse, or death (from any cause), whichever occurred first. Results: Bearman toxicity data are available for all patients. Among these patients, grade 2 toxicities were bladder toxicity and stomatitis. No grade 3-4 toxicities or toxicity-related deaths were observed. Acute GVHD (aGVHD) developed in 2 of patients (100-day Grade II-IV aGVHD: 11.1%, 95%CI: 1.7-30.4); of those, only 1 patient developed Grades III-IV (100-day Grade III-IV aGVHD: 5.6%, 95%CI: 0.3-23.1). Five patients developed mild chronic GVHD (1-year cGVHD rate: 28.6%, 95%CI: 7.5%-54.7%). The GRFS rate at 1 year was 59.3% (95% CI: 28.8-80.3) (Figure). The median follow up was 11.3 months (range 4.7 to 25.4) for surviving patients (n=17). All patients engrafted. Time to neutrophil and platelet recovery were 14 days (range 13-32 days) and 20 days (range 11-49 days), respectively. One-year estimates of OS and relapse-free survival were 100% and 80.8% (95% CI: 50.5-93.6), respectively (Figure). Disease relapse at 1 year was 19.2% (95% CI: 4.1-42.6). The estimates of NRM at 100 days and 1 year were both 0%. Relapsed disease after transplant occurred in 3 patients (16.7%). One patient died after relapse. Conclusions: 1) This chemotherapy-free conditioning regimen, together with PTCy and tacrolimus, is safe and feasible, with no NRM. 2) All patients achieved engraftment. 3) Participants with ≥1 year follow-up have discontinued immunosuppressive therapy, reducing financial burden and leading to improved quality of life. The preliminary results suggest an improved GRFS rate. A larger phase 2 trial is in preparation to corroborate these data. Disclosures Stein: Amgen: Consultancy, Speakers Bureau; Stemline: Consultancy, Speakers Bureau. Al Malki:Neximmune: Consultancy; Jazz Pharmacuticals, Inc: Consultancy; Rigel Pharma: Consultancy. Ali:Incyte Corporation: Consultancy. Aribi:Seattle Genetics: Consultancy. Marcucci:Novartis: Speakers Bureau; Takeda: Other: Research Support (Investigation Initiated Clinical Trial); Pfizer: Other: Research Support (Investigation Initiated Clinical Trial); Abbvie: Speakers Bureau; Merck: Other: Research Support (Investigation Initiated Clinical Trial); Iaso Bio: Membership on an entity's Board of Directors or advisory committees. Nakamura:Alexion: Other: Support on a meeting presentation; Kyowa-Kirin: Other: Support on a meeting presentation; Merck: Other: advisory board meeting; Celgene: Other: Support on seminar; Magenta Therapeutics: Other: Advisory board meeting; Viracor: Consultancy; Kadmon Corporation: Other: Advisory board meeting; NapaJen Pharma: Consultancy. Pullarkat:AbbVie, Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genetech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Dova: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Salhotra:Celgene: Research Funding; Kadmon: Membership on an entity's Board of Directors or advisory committees.

The "7+3" regimen is recommended for treatment in patients with new diagnosis of acute myeloid leukemia (AML) who are fit for intensive chemotherapy. Patients with secondary AML (sAML) [i.e. AML evolving from antecedent hematologic disorders (AHD-AML) or after previous exposure to chemo/radiation therapy for unrelated cancer (t-AML)], have inferior outcomes with "7+3" regimen. A recent phase 3 study demonstrated superior CR rates and overall survival (OS) with upfront use of CPX-351 compared to "7+3" regimen in older patients (≥60 years) with sAML (Lancet et al JCO 2018). The combination of HMA+Ven is FDA approved for upfront treatment in newly diagnosed AML patients > 75 or those unfit for intensive chemotherapy based on CR+ CRi rates of 67% and median OS of 17.5 months. Herein, we compared the outcomes of older patients with sAML who received upfront treatment with either HMA+Ven or CPX-351 at our institution. Our analysis includes 47 consecutive patients with previously untreated sAML treated between 2018-2020 . Patients were treated with either HMA+Ven (n=27) or CPX-351 (n=20) based on physician preference. WHO criteria were used for the diagnosis AHD-AML and review of medical records for documenting exposure to leukemogenic agent for t-AML. Complete remission (CR) was defined by presence of 1000/µL and platelets ≥100,000/µL) were defined as CRh (hematologic recovery) and CR without blood count recovery as CRi (incomplete blood count recovery). Minimal residual disease (MRD) assessment was done on day-28 BM aspirate using multiparametric flow cytometric assay with lower limit of sensitivity of 0.01%. Patients demographic and disease features are summarized in Table 1. Mean age (p=0.39), mean blast percentage in BM aspirate (P=0.82), high-risk cytogenetics (P=0.37) and high-risk molecular mutations (P=0.737) were similar in both treatment groups. Of the 27 cases of sAML in HMA+Ven group, 8 were t-AML arising after prior chemotherapy (Hodgkin's Disease n=2; paraganglioma, desmoid tumor, breast cancer, NHL, multiple myeloma, ALL: one each) while 19 were AHD-AML. In CPX-351 group, 6 cases were t-AML arising after prior chemotherapy (NHL n=2, breast cancer n=2, T-Lymphoblastic Lymphoma and colon cancer one each) while 14 were secondary to AHD. The mean number of cycles were 3.3 (range 1-18) in HMA+Ven group and 1.45 (1-3) in CPX-351 group. Two-sample t test was used to compare continuous and normally distributed covariates, such as age and BM blasts, between HMA+Ven or CPX-351 arms. Pearson Chi-square or Fisher exact test was used to assess the associations between treatment and clinical outcomes. Kaplan-Meier method and log-rank test were used to assess OS or LFS. A P value of ≤ 0.05 was considered as statistically significant. The CR rate in patients treated on HMA+Ven group was 78% (n=21; 95% CI: 58-91%) vs 50% (n=10; 95% CI: 27-73%) in CPX-351 group (P=0.047). CRi was achieved in 52% (n=14) patients in HMA+Ven group compared to 25%(n=5) patients in CPX-351 group(p=0.064). MRD negative remission was achieved in 52% (n=14) patients in HMA+Ven group and in 25% (n=5) patients in CPX-351 group (p=0.064). In HMA+Ven group, 52% patients (n=14) achieved remission after one cycle of therapy compared to 45% (n=9) patients in CPX-351 arm (p=0.642). With a median follow-up of 6.7 months for all patients, the median leukemia free-survival (LFS) for HMA+Ven vs CPX-351 treatments is 16.2 vs NA months (P = 0.098) and the median OS is 13.2 vs NA months (P = 0.395). Ten patients in each group (37% in HMA+Ven and 50% in CPX-351; p=0.47) underwent allo-HCT. At last follow up, 14 patients (52%) have died in HMA+Ven group from: relapsed AML (n=10), sepsis (n=2), congestive heart failure (n=1) and unknown (UK) in one patient, whereas in CPX-351 group, 8 patients (40%) have died from relapsed AML in (n=5), respiratory failure (n=2) and UK causes in one patient. In patients resistant to initial therapy, the median OS is 3.5 vs 6.0 months between HMA+ Ven and CPX-351 groups (P = 0.224). Conclusion: In patients presenting with sAML, upfront treatment with HMA+Ven is feasible and associated with significantly better CR rates and a favorable trend for higher rates of negative MRD compared to CPX-351. A randomized prospective trial in patients with sAML is warranted to determine the most effective frontline regimen in this high-risk AML subgroup. Disclosures Salhotra: Celgene: Research Funding; Kadmon: Membership on an entity's Board of Directors or advisory committees. Al Malki:Rigel Pharma: Consultancy; Neximmune: Consultancy; Jazz Pharmacuticals, Inc: Consultancy. Aribi:Seattle Genetics: Consultancy. Ali:Incyte Corporation: Consultancy. Budde:Gilead Sciences: Consultancy; Merck: Research Funding; Amgen: Research Funding; Kite, a Gilead Company: Consultancy; Mustang Therapeutics: Research Funding; AstraZeneca: Research Funding; Roche: Consultancy. Dadwal:Ansun Biopharma: Research Funding; Karius: Research Funding; Shire/ Takeda: Research Funding; Gilead: Research Funding; Merck: Consultancy, Honoraria, Other: Advisory board meeting, Research Funding, Speakers Bureau; Chimerix: Research Funding; Janssen: Other: Advisory board meeting; Astellas: Speakers Bureau. Nakamura:NapaJen Pharma: Consultancy; Kadmon Corporation: Other: Advisory board meeting; Viracor: Consultancy; Magenta Therapeutics: Other: Advisory board meeting; Celgene: Other: Support on seminar; Kyowa-Kirin: Other: Support on a meeting presentation; Alexion: Other: Support on a meeting presentation; Merck: Other: advisory board meeting. Stein:Amgen: Consultancy, Speakers Bureau; Stemline: Consultancy, Speakers Bureau. Marcucci:Takeda: Other: Research Support (Investigation Initiated Clinical Trial); Merck: Other: Research Support (Investigation Initiated Clinical Trial); Iaso Bio: Membership on an entity's Board of Directors or advisory committees; Abbvie: Speakers Bureau; Novartis: Speakers Bureau; Pfizer: Other: Research Support (Investigation Initiated Clinical Trial). Pullarkat:Dova: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genetech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie, Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. OffLabel Disclosure: off label use of HMA+venetoclax in secondary AML

The use of post-transplant cyclophosphamide (PTCy) as graft-versus-host-disease (GvHD) prophylaxis after hematopoietic cell transplantation (HCT) has increased significantly over the past decade due to expansion of donor pool with haploidentical and mismatched unrelated donors. A recently completed phase 2 study, PROGRESS-2 (NCT02345850), has highlighted the efficacy of PTCy in the matched donor setting. Hemorrhagic cystitis (HC) is the most notable toxicity associated with high dose Cy. However, data specific to the incidence and severity of HC in the post HCT setting is sparse, with no consensus on best practices to prevent HC in patients receiving PTCy. Current strategies to prevent HC in PTCy setting have been adapted from data in pre-HCT Cy (conditioning setting), such as hyperhydration with forced diuresis, continuous bladder irrigation, mesna as an intermittent and continuous infusion, or a combination of these methods. The aim of our study was to describe the incidence and severity of HC in patients undergoing HCT with PTCy as GvHD prophylaxis, identifying potential risk factors and impact of HC on HCT outcomes. We retrospectively reviewed 194 consecutive patients who underwent their first HCT with PTCy from 2014 to 2018 at our center. More than half of the patients (53%) received myeloablative conditioning regimen with majority receiving peripheral blood stem cells (81%) from haploidentical donors (96%). GvHD prophylaxis was unified with PTCy (50 mg/kg on Days +3 and +4), in addition to MMF (1 gm 3x daily starting on Day +5) and tacrolimus (1 mg as a continuous infusion daily starting on Day +5). Standard HC prophylaxis was hyperhydration with forced diuresis and mesna at 320% the daily dose of PTCy. Incidence of HC was based on physician documentation or presence of blood in urinalysis up to Day +100. To determine severity of HC, CTCAE 5.0 grading system was used. Median age of patients was 45 years (range: 2-73), with 60% of patients being male. KPS was ≥80% in 83% of patient and 40% had HCT-CI of ≥2. The most common diagnoses included: AML (41%), ALL (24%) and MDS/MPN (19%). There were 55 patients who received ≥3 lines of therapy, 116 patients received In conclusion, hyperhydration with forced diuresis added to aggressive mesna dosing is an effective strategy in preventing severe HC in HCT patients receiving PTCy as GvHD prophylaxis. Incidence of Grade 3 or 4 HC was low and transient and did not impact HCT outcomes. Viral HC had a significantly later onset than non-viral HC, suggesting a different pathophysiology. Older age and myeloablative conditioning were independent factors for higher incidence of HC in our cohort. Disclosures Ali: Incyte Corporation: Consultancy. Salhotra:Celgene: Research Funding; Kadmon: Membership on an entity's Board of Directors or advisory committees. Aribi:Seattle Genetics: Consultancy. Pullarkat:Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie, Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genetech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Dova: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Stein:Amgen: Consultancy, Speakers Bureau; Stemline: Consultancy, Speakers Bureau. Marcucci:Merck: Other: Research Support (Investigation Initiated Clinical Trial); Pfizer: Other: Research Support (Investigation Initiated Clinical Trial); Abbvie: Speakers Bureau; Novartis: Speakers Bureau; Iaso Bio: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Research Support (Investigation Initiated Clinical Trial). Nakamura:NapaJen Pharma: Consultancy; Viracor: Consultancy; Kadmon Corporation: Other: Advisory board meeting; Magenta Therapeutics: Other: Advisory board meeting; Celgene: Other: Support on seminar; Kyowa-Kirin: Other: Support on a meeting presentation; Alexion: Other: Support on a meeting presentation; Merck: Other: advisory board meeting. Al Malki:Rigel Pharma: Consultancy; Jazz Pharmacuticals, Inc: Consultancy; Neximmune: Consultancy.

Therapy-related myelodysplastic syndrome is a long-term complication of cancer treatment in patients receiving cytotoxic therapy, characterized by high-risk genetics and poor outcomes. Allogeneic hematopoietic cell transplantation is the only potential cure for this disease, but the prognostic impact of pre-transplant genetics and clinical features has not yet been fully characterized. We report here the genetic and clinical characteristics and outcomes of a relatively large cohort of patients with therapy-related myelodysplastic syndrome (n=67) who underwent allogeneic transplantation, comparing these patients to similarly treated patients with de novo disease (n=199). The 5-year overall survival was not different between patients with therapy-related and de novo disease (49.9% versus 53.9%; P=0.61) despite a higher proportion of individuals with an Intermediate-2/High International Prognostic Scoring System classification (59.7% versus 43.7%; P=0.003) and high-risk karyotypes (61.2% versus 30.7%; P

The presence of FMS-like receptor tyrosine kinase-3 internal tandem duplication (FLT3-ITD) mutations in patients with acute myeloid leukemia (AML) is associated with poor clinical outcome. FLT3 tyrosine kinase inhibitors (TKIs), although effective in kinase ablation, do not eliminate primitive FLT3-ITD+ leukemia cells, which are potential sources of relapse. Thus, understanding the mechanisms underlying FLT3-ITD+ AML cell persistence is essential to devise future AML therapies. Here, we show that expression of protein arginine methyltransferase 1 (PRMT1), the primary type I arginine methyltransferase, is increased significantly in AML cells relative to normal hematopoietic cells. Genome-wide analysis, coimmunoprecipitation assay, and PRMT1-knockout mouse studies indicate that PRMT1 preferentially cooperates with FLT3-ITD, contributing to AML maintenance. Genetic or pharmacological inhibition of PRMT1 markedly blocked FLT3-ITD+ AML cell maintenance. Mechanistically, PRMT1 catalyzed FLT3-ITD protein methylation at arginine 972/973, and PRMT1 promoted leukemia cell growth in an FLT3 methylation–dependent manner. Moreover, the effects of FLT3-ITD methylation in AML cells were partially due to cross talk with FLT3-ITD phosphorylation at tyrosine 969. Importantly, FLT3 methylation persisted in FLT3-ITD+ AML cells following kinase inhibition, indicating that methylation occurs independently of kinase activity. Finally, in patient-derived xenograft and murine AML models, combined administration of AC220 with a type I PRMT inhibitor (MS023) enhanced elimination of FLT3-ITD+ AML cells relative to AC220 treatment alone. Our study demonstrates that PRMT1-mediated FLT3 methylation promotes AML maintenance and suggests that combining PRMT1 inhibition with FLT3 TKI treatment could be a promising approach to eliminate FLT3-ITD+ AML cells.

Allogeneic hematopoietic cell transplantation (alloHCT) is the only curative therapy for primary myelofibrosis (MF) as well as myelofibrosis secondary to other myeloproliferative neoplasms (MPN). Pulmonary hypertension (PH) is a known complication of MF and may occur in up to 50% of such patients. PH (defined as a mean pulmonary artery pressure ≥25 mmHg at rest) can eventually lead to right heart failure and may be associated with complications after alloHCT. We examined the association of PH with alloHCT outcome in patients with MF associated with MPN. Pre- and post-HCT echocardiograms were reviewed to estimate the peak pulmonary artery systolic pressure (PASP). Median PASP was 37.0 mmHg (range: 16.0-57.9) prior to HCT with 37 of 65 patients (57%) studied. With median follow-up of 35.0 months (range: 3.3–119.4) PH was significantly associated with inferior OS (58.9% vs. 88.8%, P = 0.025), primarily due to increased NRM (21.6% vs. 7.1%, P = 0.007). The majority of the deaths (8 of 14) in patients with PH occurred within 100 days after HCT. In patients with an available post-HCT echocardiogram (n = 33), the median PASP was 30 mmHg (range: 5.0–56.2); eight patients (24%) had persistent PH. Compared with pre-HCT values, PASP was significantly reduced after HCT (p

T cell-based therapies (blinatumomab and CAR T cell therapy) have produced unprecedented responses in relapsed and refractory (r/r) acute lymphoblastic leukemia (ALL) but is accompanied with significant toxicities, of which one of the most common and serious is cytokine release syndrome (CRS). Here we will review the pathophysiology, prevention, and treatment of CRS. Efforts have been initiated to define and grade cytokine release syndrome (CRS), to identify patients at risk, to describe biomarkers that predict onset and severity, to understand the pathophysiology, and to prevent and treat severe cases to reduce T cell immunotherapy-related morbidity and mortality. Optimizing the timing of T cell-based therapies in ALL, identifying new biomarkers, and investigating novel anti-cytokine agents that have anti-CRS activity are likely to be fruitful avenues of study.

Background Patients with relapsed or refractory FLT3 internal tandem duplication (FLT3-ITD)-positive acute myeloid leukaemia have a poor prognosis, including high frequency of relapse, poorer response to salvage therapy, and shorter overall survival than those with FLT3 wild-type disease. We aimed to assess whether single-agent quizartinib, an oral, highly potent and selective type II FLT3 inhibitor, improves overall survival versus salvage chemotherapy. Methods QuANTUM-R is a randomised, controlled, phase 3 trial done at 152 hospitals and cancer centres in 19 countries. Eligible patients aged 18 years or older with ECOG performance status 0-2 with relapsed or refractory (duration of first composite complete remission 30 days if suspected to be a treatment-related event) for quizartinib (241 patients) and chemotherapy (94 patients) were sepsis or septic shock (46 patients [19%] for quizartinib vs 18 [19%] for chemotherapy), pneumonia (29 [12%] vs eight [9%]), and hypokalaemia (28 [12%] vs eight [9%]). The most frequent treatment-related serious adverse events were febrile neutropenia (18 patients [7%]), sepsis or septic shock (11 [5%]), QT prolongation (five [2%]), and nausea (five [2%]) in the quizartinib group, and febrile neutropenia (five [5%]), sepsis or septic shock (four [4%]), pneumonia (two [2%]), and pyrexia (two [2%]) in the chemotherapy group. Grade 3 QT prolongation in the quizartinib group was uncommon (eight [3%] by central reading, ten [4%] by investigator report); no grade 4 events occurred. There were 80 (33%) treatment-emergent deaths in the quizartinib group (31 [13%] of which were due to adverse events) and 16 (17%) in the chemotherapy group (nine [10%] of which were due to adverse events). Interpretation Treatment with quizartinib had a survival benefit versus salvage chemotherapy and had a manageable safety profile in patients with rapidly proliferative disease and very poor prognosis. Quizartinib could be considered a new standard of care. Given that there are only a few available treatment options, this study highlights the value of targeting the FLT3-ITD driver mutation with a highly potent and selective FLT3 inhibitor.

The success of all-trans retinoid acid (ATRA) in acute promyelocytic leukemia (APL) pioneered the concept of differentiation therapy. However, comparable approaches to overcome differentiation blockage for non-APL acute myeloid leukemia (AML) are hampered by lack of an effective drug discovery platform. Recently, we analyzed gene signatures of compounds (ATRA, arsenic trioxide, zalcitabine, and sodium butyrate) that trigger myeloid differentiation in the NCI-60 collection datasets and identified CD38 as the top gene upregulated by differentiation induction. We next initiated an in silico screen in the DTP database of >20,000 compounds to identify compounds that increase CD38 levels. Among those retrieved from "CellMiner" with CD38 as input, we assessed the top 193 available from NCI (r>0.6, p=0) for effects on differentiation utilizing a conditional murine myeloid differentiation-arrest model overexpressing estrogen receptor-HoxA9 (ER-HoxA9) fusion proteins (Cell, 2016). We identified NSC755985 (Nelarabine, NEL) in that screen. NEL is an orphan drug approved to treat relapsed or refractory T-cell acute lymphoblastic leukemia (ALL). NEL at clinically achievable doses (Cmax: 6.73 μM~ 26.91 μM, at a proposed adult dosing schedule of 1,500 mg/m2/day) markedly induced primary AML cell differentiation and death while sparing normal hematopoietic cells (AML vs normal, IC50: 14.7 ± 4.3 μM, n=7, vs 45.3 ± 1.3 μM, n=3), suggesting a therapeutic window in AML. Ex vivo NEL treatment compromised BM engraftment of CD34+ cells from one primary AML specimen in immunodeficient NSG mice at 12 weeks post-transplant (human CD45+ cells in BM: NEL 0.73% vs vehicle 33.42%, n=6/group, p Transcriptome analyses in U397 cells and primary AML specimens revealed that NEL treatment upregulated RAS-related pathways. NEL-elicited RAS activation was confirmed by pull-down assay using a GST-Raf1-RBD affinity probe, followed by blotting with a pan-RAS antibody. We performed functional analysis by infecting ER-HoxA9 cells with lentiviral vector expressing oncogenic RAS and observed enhanced myeloid differentiation, as evidenced by increased CD11b/GFP levels relative to MOCK-infected controls. Given that NEL's active metabolite Ara-GTP perturbs guanine nucleotide metabolism, we asked if NEL-evoked RAS activation was associated with accrual of intracellular GTP. HPLC/MS analyses of U937 cells showed that NEL treatment resulted in a marked increase in GTP (approximately 5-fold higher than baseline at sub-millimolar levels) which was secondary to Ara-GTP. Importantly, either electroporation of GTP into U937 cells or indirect introduction of GTP by addition of guanine utilizing purine salvage pathways activated RAS and recapitulated differentiation induction phenotypes. To determine whether AML cells with higher RAS activity exhibited greater NEL sensitivity, we pretreated U937 cells with a RAS agonist KRA-553 or ectopically expressed RAS mutants and observed enhanced NEL inhibitory effects in both cases. We also observed enhanced vulnerability to NEL treatment in MLL-AF9 transformed murine hematopoietic cells from KrasLox-Stop-Lox (LSL) G12D/+/Vav-Cre mice (Blood, 2009) versus Cre+ counterparts. Relevant to AML line THP-1 which is poorly responsive to NEL (IC50>100 µM), we observed extremely low levels of Ara-GTP, no GTP increase or RAS hyperactivation after NEL treatment; Ara-GTP is inactivated by SAM domain and HD domain-containing protein 1 (SAMHD1), a dNTP hydrolase, whose high expression reportedly underlies NEL resistance in T-ALL. Indeed, SAMHD1 deletion remarkably increased RAS activity in THP-1 cells treated with NEL, thereby fully reversing NEL resistance. Our study provides a preclinical basis for testing NEL efficacy in a large cohort of AML patients, given that RAS activity is generally high in AML, or even against other malignancies harboring RAS mutations, which are considered "undruggable". Additionally, further study to test whether SAMHD1 inhibition enhances NEL efficacy against RAS active cancers is warranted. Disclosures Marcucci: Pfizer: Other: Research Support (Investigation Initiated Clinical Trial); Novartis: Speakers Bureau; Takeda: Other: Research Support (Investigation Initiated Clinical Trial); Iaso Bio: Membership on an entity's Board of Directors or advisory committees; Merck: Other: Research Support (Investigation Initiated Clinical Trial); Abbvie: Speakers Bureau. Sykes:Clear Creek Bio: Current equity holder in private company, Other: co-founder.

Allogeneic hematopoietic cell transplantation (HCT) may produce long-term survival in AML after relapse or primary induction failure (PIF). However, outcomes of HCT performed for AML not in remission are historically poor given high relapse rates and transplant-related mortality. Preliminary studies suggest conditioning with clofarabine and myeloablative busulfan (CloBu4) may exert significant anti-leukemic effects without excessive toxicity in refractory hematologic malignancies. A prospective multicenter phase II trial was conducted to determine the efficacy of CloBu4 for patients proceeding directly to HCT with AML not in remission. Seventy-one patients (median age: 56 years) received CloBu4. At day 30 after HCT, 90% achieved morphologic remission. The incidence of non-relapse mortality and relapse at 2 years was 25% and 55%, respectively. The 2-year overall survival (OS) and event-free survival (EFS) were 26% and 20%, respectively. Patients entering HCT in PIF had significantly greater EFS than those in relapse (34% vs 8%; P

Myeloablative autologous hematopoietic stem cell transplantation (HSCT) is a mainstay of therapy for relapsed intermediate-grade B-cell non-Hodgkin lymphoma (NHL); however, relapse rates are high. In phase 1 studies designed to improve long-term remission rates, we administered adoptive T-cell immunotherapy after HSCT, using ex vivo-expanded autologous central memory-enriched T cells (TCM) transduced with lentivirus expressing CD19-specific chimeric antigen receptors (CARs). We present results from 2 safety/feasibility studies, NHL1 and NHL2, investigating different T-cell populations and CAR constructs. Engineered TCM-derived CD19 CAR T cells were infused 2 days after HSCT at doses of 25 to 200 × 10(6) in a single infusion. In NHL1, 8 patients safely received T-cell products engineered from enriched CD8(+) TCM subsets, expressing a first-generation CD19 CAR containing only the CD3ζ endodomain (CD19R:ζ). Four of 8 patients (50%; 95% confidence interval [CI]: 16-84%) were progression free at both 1 and 2 years. In NHL2, 8 patients safely received T-cell products engineered from enriched CD4(+) and CD8(+) TCM subsets and expressing a second-generation CD19 CAR containing the CD28 and CD3ζ endodomains (CD19R:28ζ). Six of 8 patients (75%; 95% CI: 35-97%) were progression free at 1 year. The CD4(+)/CD8(+) TCM-derived CD19 CAR T cells (NHL2) exhibited improvement in expansion; however, persistence was ≤28 days, similar to that seen by others using CD28 CARs. Neither cytokine release syndrome nor delayed hematopoietic engraftment was observed in either trial. These data demonstrate the safety and feasibility of CD19 CAR TCM therapy after HSCT. Trials were registered at www.clinicaltrials.gov as #NCT01318317 and #NCT01815749.

Allelic variants of genes implicated in drug absorption, distribution, metabolism, and excretion (ADME) determine the pharmacokinetic variability of many medications and are increasingly recognized as important factors determining the success or failure of medical treatments. Both tacrolimus and sirolimus have narrow therapeutic ranges maintained by therapeutic drug monitoring (TDM). Using an ADME panel that covers >99% of the PharmaADME working group core list (188 single nucleotide polymorphism [SNP] and 12 copy number variant [CNV] assays in 36 pharmacogenetically relevant genes), we studied 177 patients who underwent allogeneic hematopoietic cell transplantation (HCT) using tacrolimus/sirolimus–based graft-versus-host disease (GVHD) prophylaxis. We tested for possible associations between ADME variants and tacrolimus/sirolimus drug levels, concentration/dose (C/D) ratio, and clinical endpoints, including acute GVHD. A total of 62 SNP and 6 CNV assays were evaluable after removing the variants, which were homozygous in (nearly) all samples. For sirolimus, rs2032582 (ABCB1) T-carriers versus non–T-carriers were associated with higher blood levels (P = .01), with similar results for C/D ratio. Generalized estimating equation analysis supported these findings. For tacrolimus, rs776746 CYP3A5*3/*3 and CYP3A5*3/*1 were associated with higher blood levels than CYP3A5*1/*1 (P = .002). By multivariable analysis, rs776746 CYP3A5*3/*3 and CYP3A5*3/*1 were independently associated with decreased acute GVHD compared with CYP3A5*1/*1, after adjustment for conditioning, donor type, race/ethnicity, and age. We demonstrated association of specific ADME genetic polymorphisms with blood levels of tacrolimus/sirolimus, and incidence of acute GVHD after HCT, in spite of TDM and dose adjustment. A larger ongoing study will determine whether these associations have clinical utility beyond TDM.

Introduction: We evaluated the impact of baseline (BL) co-mutations and FLT3-ITD VAF on overall survival (OS) and response (composite complete remission [CRc]) to quizartinib and SC in the phase III QuANTUM-R trial. Methods: We analyzed 37 recurrently mutated genes in AML in BL samples from 304 patients (pts) (83% of ITT population) with R/R FLT3-ITD-positive AML using next-generation sequencing and a customized Archer® Core Myeloid panel. Positive mutation status was defined as ≥1 mutation detected in the gene region using a VAF cutoff of 2.7%. FLT3-ITD VAF was measured by the Navigate BioPharma FLT3 Mutation Assay (polymerase chain reaction-based, VAF cutoff of 3%). Low and high FLT3-ITD VAF were defined as ≤25% and >25%, respectively. Results: In addition to FLT3-ITD, the prevalence of key BL co-mutations were 59.9% for DNMT3Amut and 55.3% for NPM1mut. Pts with DNMT3Amut treated with quizartinib had significantly longer OS vs SC (6.3 and 5.4 mos, respectively; hazard ratio [HR], 0.652), p Conclusions: Key co-mutations identified here potentially affect treatment response and OS with quizartinib vs SC. Our results suggest that molecular subsets of R/R AML pts may particularly derive clinical benefit from quizartinib. TableCRc, %Median OS, monthsQuizartinibSCQuizartinibSCHR95% CIITT Population (N = 367)a48276.24.70.760.58-0.98Single Gene Analyses (n = 304)bDNMT3Amut (n = 182)52376.35.40.6520.44-0.97DNMT3Awt (n = 122)40246.04.60.8490.53-1.37NPM1mut (n = 168)48395.14.70.9540.63-1.44NPM1wt (n = 136)47218.55.10.4850.31-0.76TET2mut (n = 98)34326.22.90.6640.38-1.16TET2wt (n = 206)54306.35.40.7280.51-1.05CEBPAmut (n = 46)44428.58.71.9220.80-4.62CEBPAwt (n = 258)48296.24.50.6130.45-0.84IDH1/2mut (n = 49)32275.53.70.4270.20-0.92IDH1/2wt (n = 255)51316.55.10.750.54-1.04Double Gene Analyses (n = 304)NPM1wt/DNMT3Amut (n = 44)61279.04.50.2390.09-0.61NPM1mut/DNMT3Amut (n = 138)50405.45.40.8370.52-1.34FLT3-ITD VAF AnalysesFLT3-ITD high VAF50195.53.90.6890.51-0.93FLT3-ITD low VAF43467.96.10.8570.53-1.40FLT3-ITD VAF Analyses in Selected MutationsDNMT3Amut high VAF53215.82.70.6260.40-0.98DNMT3Amut low VAF526910.26.40.7370.36-1.51NPM1wt/DNMT3Amut high VAF6409.01.50.01790.002-0.16NPM1wt/DNMT3Amut low VAF555011.36.20.3720.11-1.23aN = 367; quizartinib, n = 245; SC, n = 122bBaseline bone marrow samples were available and viable from 304 of 367 pts in the ITT population Citation Format: Alexander E. Perl, Jorge E. Cortes, Siddhartha Ganguly, Samer K. Khaled, Alwin Krämer, Giovanni Martinelli, Nigel H. Russell, Ken C. Chang, Kazunobu Kato, Yuhu Yan, Li-An Xu, Sergey Korkhov, Tobias Günnel, Hiroyuki Sumi, Arnaud Lesegretain, Flora Berisha, Derek Mires, Aziz Benzohra, Takeshi Isoyama, Cedric Dos Santos, Mark J. Levis. Effect of co-mutations and FLT3-ITD variant allele frequency (VAF) on response to quizartinib or salvage chemotherapy (SC) in relapsed/refractory (R/R) acute myeloid leukemia (AML) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 784.

7556 Background: Hypomethylating agents (HMA), such as azacitidine (AZA), are the standard of care for patients (pts) with higher-risk myelodysplastic syndromes (MDS). However, overall response rate (ORR=CR+PR) with HMA alone is approximately 30%, with a 2-year overall survival (OS) rate of 50.8%. Preclinical studies show that pracinostat (PRAN), an oral histone deacetylase inhibitor, synergizes with HMA. A study in pts with untreated IPSS intermediate-2/high-risk MDS receiving 60 mg PRAN plus AZA resulted in early discontinuations, mainly due to adverse events (AE), potentially leading to diminished clinical benefit. This follow-up phase II study evaluates a lower dose of PRAN (25% reduction) in combination with AZA in order to reduce toxicity, decrease early discontinuations, and improve outcomes. An interim analysis showed low discontinuation rate and promising efficacy, allowing trial expansion. Herein, we report preliminary safety and efficacy in the overall population. Methods: Open-label, II-stage, phase II trial (NCT03151304) in pts (≥18 years) naive to HMA therapy and with IPSS-R of high/very high-risk MDS. Planned enrollment was 60 pts. Pts received 45 mg PRAN 3 days/week for 3 consecutive weeks plus standard AZA dose for 7 days of each 28-day cycle. Primary objectives were to define the safety/tolerability of the combination and to assess the ORR (CR+PR). OS was a secondary endpoint. Results: Sixty-four pts were enrolled and received ≥1 dose of treatment. Most pts were male (67%), median age was 68 years (range 47–89), and the proportion of pts with high/very high-risk MDS was similar. After 17.6 months’ median follow-up, 31% of pts remain on treatment; 69% of pts discontinued treatment due to stem cell transplant (25%), disease progression (17%), AEs (11%), consent withdrawal (3%), pt noncompliance (3%), death (3%), lost to follow-up (2%), and other (5%). Most common nonhematologic AEs were constipation (55%), nausea (52%), fatigue (45%), decreased appetite (39%), peripheral edema (36%), diarrhea, and dyspnea (31% each). Frequent hematologic AEs were decreased neutrophil count (50%), anemia (39%), decreased platelet count (38%), febrile neutropenia (36%), and thrombocytopenia (30%). ORR was 33% (95% CI 22-46), with 33% achieving CR; 34% of pts had marrow CR. Median OS was 23.5 months (95% CI 16.4-nc), with an estimated 1-year OS of 77%. Conclusions: In pts with high/very high-risk MDS, a lower dose of pracinostat in combination with AZA demonstrated a tolerable safety profile and promising efficacy. Clinical trial information: NCT03151304 .

Introduction In QuANTUM-R, the once-daily, oral, highly potent and selective FLT3 inhibitor Q improved clinical benefit vs SC (median overall survival [mOS], 6.2 vs 4.7 mo [HR, 0.76 (95% CI, 0.58-0.98); P = .02]) in R/R FLT3-ITD AML (NCT02039726). Before randomization, 25% (Q) and 23% (SC) of pts had 1 prior HSCT. Objective To describe post hoc analyses in pts who underwent subsequent HSCT during QuANTUM-R. Methods Pts with FLT3-ITD R/R AML received Q (60 mg [30-mg lead-in]) or SC. Pts in the Q arm could resume Q 30-100 d after HSCT. Decisions to proceed to HSCT and resume Q after HSCT were made per investigator discretion/institutional policy. Results Of 367 randomized pts, 85 in the Q arm underwent any subsequent HSCT (allogeneic HSCT [allo-HSCT], 84 [6 with and 78 w/o additional AML therapy]; autologous HSCT, 1), and 19 in the SC arm underwent any HSCT (5 with and 14 w/o additional AML therapy]). Q + SC pooled data showed a longer mOS (95% CI) in 104 pts with any HSCT vs 263 w/o (12.2 [10.0-24.1] vs 4.4 [4.1-4.9] mo; P Regardless of treatment, mOS was longer with any HSCT vs w/o (Q, 11.9 [10.2-25.1] vs 4.5 [4.1-5.4] mo; SC, 12.7 [6.1-NA] vs 4.0 [2.7-5.0] mo); respective 1-year OS rates were 50% vs 13% and 51% vs 12%. In the Q arm, mOS (95% CI) was longer in pts with a best response of CRc who resumed Q after allo-HSCT (27.1 [18.2-NA] mo) vs pts not resuming Q (5.4 [4.7-11.4] mo; Fig 2). In 48 pts (62%) in the Q arm resuming Q after allo-HSCT, median time from allo-HSCT to Q resumption was 65 d (range, 30-106 d). Four pts (5%) in the Q arm died Conclusion Independent of HSCT, Q improved survival vs SC in pts with FLT3-ITD R/R AML in QuANTUM-R. Q + SC pooled analyses showed longer survival in pts with HSCT vs pts w/o and in pts with CRc before allo-HSCT. Survival in transplanted pts was similar in both arms, indicating that HSCT-eligible pts received transplants appropriately, and the higher HSCT rate in the Q arm was beneficial. In pts preselected for low-intensity SC at study entry, 13 were able to undergo HSCT after Q treatment. Q resumption after HSCT was associated with better survival outcomes and was tolerable. These data illustrate the value of using Q to target the FLT3-ITD mutation as a part of the overall treatment sequence in pts with FLT3-ITD R/R AML.

Despite of the continuous increase in the number of volunteer donors available through the registry, many patients who require an allogeneic hematopoietic cell transplantation (HCT) cannot find a fully-matched donor. While a mismatched unrelated donor (MMUD) is frequently available, it is associated with inferior outcomes and increased risk of graft-versus-host disease (GvHD). Post-transplant cyclophosphamide (PTCy) has been effective in haploidentical HCT, and increasingly used in matched donor HCTs. However, limited data exist in MMUD setting. We conducted a prospective single center trial (NCT 03128359) of PTCy for MMUD HCT with the primary objective of estimating 1-year GvHD-free relapse/progression-free survival (GRFS). As of October 2019, all planned 39 patients have been enrolled with a median follow up of 11 months (range: 1-23). Here we present the preliminary estimate of 1-year GRFS and other HCT outcomes in two strata; myeloablative conditioning (n=19) using Fludarabine (90 mg/m2) and FTBI (1200 cGy) or reduced intensity conditioning (n=19) using Fludarabine (100 mg/m2) and Melphalan (140 mg/m2 or 100 mg/m2 if >60 years old). Patients between 0 to 75 years of age and KPS of ≥70% with hematologic malignancies undergoing HCT from a 7/8 HLA-matched (A-, B-, C-, and DR-) donor were eligible. Patients with donor specific antibodies to the mismatched HLA-locus were excluded. All patient received PBMCs (3-5 × 106/kg) followed by GVHD prophylaxis consisting of PTCy (50 mg/kg for 2 days), Tacrolimus (1 mg), and mycophenolate mofetil (1 gr 3 × a day). Median age at the time of HCT was 53 years (range: 21-72), and 50% of patients were male. Disease risk was low in 47% (n=18), intermediate in 37% (n=14), and high in 16% of the patients (n=6). At transplant, 29 patients were in complete remission, and 9 had active disease. HCT-CI was 0 in six (16%) and 1-2 in 15 (39%) and >2 in 17 (45%) patients. Donors' median age was 32 years (range: 19-53) and donors were mismatched at HLA-A (n=14), -B (n=12), -C (n=8), or DR-loci (n=5). Median number of mismatches was 2 of 12 (range: 1-4). Female to male donor HCT was in 11% of recipients. Neutrophil engraftment occurred in all patients (median time to engraft: 16 days; range 13-35). One-year overall survival (OS) and GRFS were 92% (95% CI: 70-98) and 70% (95% CI: 51-83), respectively. Non-relapse mortality and relapse rate at 1 year were at 8% (95% CI: 2-29) and 13% (95% CI: 5-34), respectively. Cumulative incidence of day 100 acute GvHD grade 2-4 was 50% (95% CI: 35-71) and 1-year chronic GvHD was 56% (95% CI: 39-81). No severe chronic GvHD by the NIH criteria was observed. In conclusion, the data from our phase II trial of PTCy showed highly promising OS/GRFS in patients receiving 7/8 MMUD HCT, and that PTCy in MMUD setting offers an alternative and effective HCT approach for patients who do not have an available matched donor.

Introduction: In the phase 3 QuANTUM-R trial, once-daily, oral, highly potent and selective FLT3 inhibitor Q improved clinical benefits vs SC (median overall survival [mOS], 6.2 vs 4.7 mo [HR, 0.76 (95% CI, 0.58-0.98); P = .02]; composite complete remission [CRc], 48% vs 27%; median duration of CRc, 12.1 vs 5.0 wk) in 367 pts with R/R FLT3-ITD AML (Cortes et al. Lancet Oncol, 2019; NCT02039726). Prior to randomization, 25% (Q) and 23% (SC) of pts had 1 prior HSCT. An OS sensitivity analysis, with censoring at the time of any subsequent HSCT during QuANTUM-R, was supportive (mOS, 5.7 vs 4.6 mo [HR, 0.79 (95% CI, 0.59-1.05)]; P = .05). Post hoc analyses of characteristics and clinical outcomes in pts who underwent subsequent HSCT in QuANTUM-R are reported. Methods: Pts aged ≥ 18 y with FLT3-ITD R/R AML receiving Q (60 mg [30-mg lead-in]) or 1 of 3 prespecified high- or low-intensity SC regimens and underwent subsequent HSCT as part of the open-label, randomized QuANTUM-R trial were analyzed. Pts receiving HSCT in the Q arm could resume maintenance Q 30-100 days after HSCT. Decisions to proceed to HSCT and resume Q after HSCT were made per investigator discretion/institutional policies. Results: Of 367 randomized pts, 85 in the Q arm underwent any subsequent HSCT (allogenic HSCT [allo-HSCT], 84 [6 with and 78 w/o additional AML therapy]; autologous HSCT, 1) and 19 in the SC arm underwent any HSCT (5 with and 14 w/o additional AML therapy]). Median age (range) was lower in pts with any HSCT (Q, 49 [19-71] y; SC, 44 [23-67] y) vs pts w/o (Q, 58 [19-81] y; SC, 59 [18-78] y). Q + SC pooled data showed a longer mOS (95% CI) in 104 pts with any HSCT vs 263 w/o (12.2 [10.0-24.1] vs 4.4 [4.1-4.9] mo; P < .0001; Fig 1); 1-year OS probabilities (95% CI) were 50% (40%-60%) vs 13% (9%-18%). Among pts preselected for high-intensity therapy (Q [n = 188] + SC [n = 93]), mOS in the pooled high-intensity group was 11.9 (10.0-24.0) mo with any HSCT vs 4.6 (4.1-5.4) mo w/o. Among pts preselected for low-intensity therapy, 13/57 in the Q arm and 0/29 in the SC arm underwent any HSCT; mOS in the pooled low-intensity group was 32.4 (6.2-NA) mo with any HSCT vs 4.1 (2.7-4.6) mo w/o. In pts with CRc (last recorded response prior to allo-HSCT), mean time (range) to allo-HSCT was 13.3 (5.9-26.9) wk with Q and 12.1 (6.3-28.6) wk with SC. Q + SC pooled data showed that mOS (95% CI) was longer in pts with a CRc prior to allo-HSCT vs pts w/o CRc (20.1 [11.7-NA] vs 8.8 [7.0-11.4] mo). Survival outcomes by treatment were similar regardless of study treatment, with longer mOS in pts with any HSCT vs pts w/o (Q, 11.9 [10.2-25.1] vs 4.5 [4.1-5.4] mo; SC, 12.7 [6.1-NA] vs 4.0 [2.7-5.0] mo); respective 1-year OS probabilities (95% CI) were 50% (39%-60%) vs 13% (8%-20%) and 51% (26%-70%) vs 12% (6%-21%). In the Q arm, mOS (95% CI) was longer in pts with a best response of CRc who resumed Q after allo-HSCT (27.1 [18.2-NA] mo) vs pts not resuming Q (5.4 [4.7-11.4] mo; Fig 2). In 48 pts (62%) in the Q arm resuming Q after allo-HSCT, median time (range) from allo-HSCT to Q resumption was 65 (30-106) d. Four pts (5%) in the Q arm died < 30 days after allo-HSCT. As of 2/22/2018, 46 of 78 pts in the Q arm (59%) and 9 of 14 pts in the SC arm (64%) with allo-HSCT w/o additional AML therapy died, primarily due to AML disease progression (Q, 31 [40%]; SC, 7 [50%]). The frequency of treatment-emergent adverse events (TEAEs) was mostly lower in pts resuming Q after allo-HSCT than in the overall Q population (Table 1); TEAEs of interest were similar. Long-term survivor data will be presented. Conclusions: Independent of HSCT, Q improved survival vs SC in pts with FLT3-ITD R/R AML in QuANTUM-R. Q + SC pooled analyses showed longer survival in pts with HSCT vs pts w/o and in pts with CRc prior to allo-HSCT. Importantly, survival post-HSCT was similar in the Q and SC arms, indicating that pts eligible for HSCT were appropriately transplanted, and the higher HSCT rate in the Q arm was beneficial to pts. More pts treated with Q underwent HSCT, likely due to a higher rate and duration of CRc with Q vs SC and better overall fitness. In pts preselected for low-intensity SC at study entry, 13 were able to undergo HSCT after Q treatment. Resumption of Q after HSCT was associated with better survival outcomes and was tolerable. These data illustrate the value of using Q to target the FLT3-ITD mutation as a part of the overall treatment sequence in pts with FLT3-ITD R/R AML. Disclosures Ganguly: Seattle Genetics: Speakers Bureau; Janssen: Honoraria, Other: Advisory Board; Kite Pharma: Honoraria, Other: Advisory Board; Daiichi Sankyo: Research Funding. Cortes:Bristol-Myers Squibb: Consultancy, Research Funding; BiolineRx: Consultancy; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Sun Pharma: Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Forma Therapeutics: Consultancy, Honoraria, Research Funding; Biopath Holdings: Consultancy, Honoraria; Merus: Consultancy, Honoraria, Research Funding. Krämer:Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Bayer: Research Funding. Levis:Amgen: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Daiichi Sankyo Inc: Consultancy, Honoraria; Astellas: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Menarini: Consultancy, Honoraria; FUJIFILM: Consultancy, Research Funding. Martinelli:Daiichi Sankyo: Consultancy, Honoraria; Pfizer: Consultancy, Other: trial grant; Celgene: Consultancy, Honoraria, Other: trial grant; Janssen: Consultancy, Other: trial grant; Incyte: Consultancy, Other: trial grant; Amgen: Consultancy, Other: trial grant; Abbvie: Consultancy, Honoraria, Other: trial grant; Novartis: Consultancy, Other: trial grant; Roche: Consultancy, Other: trial grant; Ariad: Consultancy, Other: trial grant. Perl:Novartis: Honoraria, Other: Advisory board, Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of the data., Research Funding; Bayer: Research Funding; BioMed Valley Discoveries: Research Funding; FujiFilm: Research Funding; Takeda: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Astellas: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings as well as a medical writing company that assisted with manuscript preparation/submission and slide deck assembly for academic meeting presentations of trial data., Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Other, Research Funding; Arog: Consultancy, Other: Non-financial support included travel costs for advisory board meetings.; AbbVie: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; Actinium Pharmaceuticals: Consultancy, Honoraria, Other: Clinical Advisory Board member, Research Funding; Agios: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Non-financial support included travel costs for advisory board meetings.; Jazz: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.; NewLink Genetics: Consultancy, Honoraria, Other: Non-financial support included travel costs for advisory board meetings.. Russell:Astellas: Consultancy, Honoraria, Speakers Bureau; Pfizer Inc: Consultancy, Honoraria, Speakers Bureau; Jazz: Consultancy, Honoraria, Speakers Bureau; DSI: Consultancy, Honoraria, Speakers Bureau. Arunachalam:Daiichi Sankyo: Employment. Gammon:Daiichi Sankyo: Consultancy. Lesegretain:Daiichi-Sankyo Inc.: Employment, Equity Ownership. Mires:Daiichi Sankyo: Employment. Namuyinga:Daiichi Sankyo: Employment. Zhang:Daiichi Sankyo: Employment. Khaled:Omeros: Consultancy; Daiichi Sankyo: Other: Travel support; Alexion: Consultancy, Speakers Bureau.