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Haploidentical donors offer a potentially readily available donor, especially for non-White patients, for blood or marrow transplantation (BMT). In this collaboration across North America, we retrospectively analyzed outcomes of first BMT using haploidentical donor and posttransplantation cyclophosphamide (PTCy) in MDS/MPN-overlap neoplasms (MDS/MPN), an otherwise incurable hematological neoplasm. We included 120 patients, 38% of non-White/Caucasian ethnicity, across 15 centers with median age at BMT 62.5 years. The median follow-up is 2.4 years. Graft failure was reported in 6% patients. At 3-years, nonrelapse mortality (NRM) was 25%, relapse 27%, grade 3-4 acute graft versus host disease (GVHD) 12%, chronic GVHD requiring systemic immunosuppression 14%, progression-free survival (PFS) 48% and overall survival (OS) 56%. On multivariable analysis, statistically significant associations included older age at BMT (per decade increment) with NRM (sdHR 3.28, 95%CI 1.30-8.25), PFS (HR 1.98, 95% 1.13-3.45) and OS (HR 2.01, 95% CI 1.11-3.63), presence of mutation in EZH2/RUNX1/SETBP1 with relapse (sdHR 2.61, 95%CI 1.06-6.44), and splenomegaly at BMT/prior splenectomy with OS (HR 2.20, 95%CI 1.04-4.65). Haploidentical donors are a viable option for BMT in MDS/MPN, especially for those disproportionately represented in the unrelated donor registry. Disease-related factors including splenomegaly and high-risk mutations dominate outcomes following BMT.

We report the results from a multicenter retrospective study of 69 adult patients who underwent haploidentical blood or marrow transplantation (haplo-BMT) with post-transplantation cyclophosphamide (PTCy) for chronic phase myelofibrosis. The median age at BMT was 63 years (range, 41-74). Conditioning regimens were reduced intensity in 54% and nonmyeloablative in 39%. Peripheral blood grafts were used in 86%. The median follow-up was 23.1 months (range, 1.6-75.7). At 3 years, the overall survival, relapse-free survival (RFS), and graft-versus-host-disease (GVHD)-free-RFS were 72% (95% CI 59-81), 44% (95% CI 29-59), and 30% (95% CI 17-43). Cumulative incidences of non-relapse mortality and relapse were 23% (95% CI 14-34) and 31% (95% CI 17-47) at 3 years. Spleen size ≥22 cm or prior splenectomy (HR 6.37, 95% CI 2.02-20.1, P = 0.002), and bone marrow grafts (HR 4.92, 95% CI 1.68-14.4, P = 0.004) were associated with increased incidence of relapse. Cumulative incidence of acute GVHD grade 3-4 was 10% at 3 months and extensive chronic GVHD was 8%. Neutrophil engraftment was reported in 94% patients, at a median of 20 days (range, 14-70). In conclusion, haplo-BMT with PTCy is feasible in patients with myelofibrosis. Splenomegaly ≥22 cm and bone marrow grafts were associated with a higher incidence of relapse in this study.

Objective/Background A few case reports in the setting of coronavirus disease 2019 (COVID-19) and multiplex polymerase chain reaction (PCR)-based assays for common respiratory pathogens have shown a higher yield of bronchoalveolar lavage (BAL) samples than upper airway specimens in immunocompromised patients. Methods A retrospective study was conducted reviewing patients diagnosed with COVID-19 at the Medical College of Wisconsin (Milwaukee, WI, USA) between March 13, 2020 and June 11, 2020. All patients tested positive for SARS-CoV-2 via real-time reverse transcriptase PCR (RT-PCR), through a nasopharyngeal or a bronchoscopy specimen. Results During the study period, 53 bronchoscopy procedures were performed at the institution, of which five patients tested positive for COVID-19. Of the five patients, three underwent BAL testing based on high clinical suspicion for COVID-19 after the nasopharyngeal (NP) swab(s) was negative. All three patients had underlying cancers and had lymphopenia for a considerable duration prior to being diagnosed with COVID-19. Two patients had better outcomes that could be attributed to earlier BAL specimen testing resulting in timely medical intervention. Conclusion This study underscores the need for early lower respiratory tract sampling, whenever possible, in patients with cancer and prolonged lymphopenia. High clinical suspicion ought to supersede false-negative NP reverse transcriptase–PCR as early bronchoscopic evaluation in cancer patients, who are either receiving active treatment or are immunosuppressed, can allow timely institution of efficacious treatment, enrollment into clinical trials, as well as effective infection control. In the apt clinical setting in patients with cancer, presumptive treatment may also be considered to minimize exposure to healthcare providers and proceduralists.

Acute GVHD (aGVHD) is a significant complication after allogeneic hematopoietic cell transplantation (HCT), occurring in up to 70% of HCT recipients. Steroid-refractory aGVHD represents a subset of patients failing initial therapy and is particularly morbid, with only 30% of patients surviving long term. Better therapies are urgently required for these patients. Here, we discuss recent advancements in the management of SR-aGVHD. We review the currently available therapies for SR-aGVHD including the results of the REACH1 and REACH2 trials, which provide the basis for the use of ruxolitinib for the treatment of SR-aGVHD. We additionally discuss newer agents under clinical investigation and will highlight the niche these agents may fill to further improve outcomes in aGVHD patient care.

Chronic graft-versus-host disease (cGVHD) is major cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Ixazomib is an oral, second-generation, proteasome inhibitor that has been shown in preclinical models to prevent GVHD. We conducted a phase I/II trial in 57 patients to evaluate the safety and efficacy of ixazomib administration for cGVHD prophylaxis in patients undergoing allogeneic HCT. Oral ixazomib was administered on a weekly basis for a total of 4 doses, beginning days +60 through +90, to recipients of matched related donor (MRD, n = 25) or matched unrelated donor (MUD, n = 26) allogeneic HCT in phase II portion of the study, once the recommended phase II dose of 4 mg was identified in phase I (n = 6). All patients received peripheral blood graft and standard GVHD prophylaxis of tacrolimus and methotrexate. Ixazomib administration was safe and well tolerated, with thrombocytopenia, leukopenia, gastrointestinal complaints, and fatigue the most common adverse events (>10%). In phase II (n = 51), the cumulative incidence of cGVHD at 1 year was 36% (95% confidence interval [CI], 19% to 54%) in the MRD cohort and 39% (95% CI, 21% to 56%) in the MUD cohort. One-year cumulative incidence of nonrelapse mortality (NRM) and relapse was 0% and 20% (95% CI, 8% to 36%) in the MRD cohort, respectively. In the MUD cohort, the respective NRM and relapse rates were 4% (0% to 16%) and 34% (17% to 52%). The outcomes on the study were compared post hoc with contemporaneous matched Center for International Blood and Marrow Transplant Research (CIBMTR) controls. This post hoc analysis showed no significant improvement in cGVHD rates in both the MRD (hazard ratio [HR] = 0.85, P = .64) or MUD cohorts (HR = 0.68, P = .26) on the study compared with CIBMTR controls. B cell activating factor plasma levels were significantly higher after ixazomib dosing in those who remained cGVHD free compared with those developed cGVHD. This study shows that the novel strategy of short-course oral ixazomib following allogeneic HCT is safe but did not demonstrate significant improvement in cGVHD incidence in recipients of MRD and MUD transplantation compared with matched CIBMTR controls. This study is registered at www.clinicaltrials.gov as NCT02250300.

An increased risk of infections has been described after T cell-replete haploidentical cell transplantation (haploHCT). Cytokine release syndrome (CRS) after haploHCT is a known phenomenon, but the impact of CRS severity on the risk of infections remains unexplored. We retrospectively evaluated 78 consecutive adult haploHCT recipients from 2012 to 2018 for the development of CRS (graded based on the criteria of Lee et al) and examined the incidence and mortality due to infections in correlation with CRS severity. In our study cohort, which was stratified into 3 groups by severity of CRS, 80% of the patients developed infections within 180 days of HCT. Significantly higher proportions of patients with CRS grade 2 (89%) and grade ≥3 (90%) than patients with CRS grade 0-1 (68%) had at least 1 infection in the first 100 days (P = .04). Bloodstream infections (BSIs) were seen more frequently in patients with CRS grade 2 and grade ≥3 in the first 6 months. Multivariable analysis for time to infection showed that CRS grade ≥3 was independently associated with an elevated risk of any infection compared with CRS grade 0-1 (hazard ratio [HR], 3.05; P = .007). CRS grade ≥3 was also associated with a higher hazard of viral (HR, 3.42; P = .04) and bacterial infections (HR, 2.83; P = .03) compared with CRS grade 0-1. After adjusting for time to neutrophil engraftment as a time-dependent covariate, CRS grade ≥3 still had a significant effect on viral infections (HR, 2.49; P = .03), but not on bacterial infections (HR, 1.32; P = .57). CRS grade was also a significant predictor for infection density (overall, bacterial, and viral). The incidence of infection-related mortality by day +100 was higher in patients with severe CRS. Severe CRS developing after post-transplantation cyclophosphamide-based haploHCT is independently associated with viral infections and an increased risk of bacterial infections, likely through delayed neutrophil engraftment.

MAPK interacting kinase (MNK), a downstream effector of mitogen-activated protein kinase (MAPK) pathways, activates eukaryotic translation initiation factor 4E (eIF4E) and plays a key role in the mRNA translation of mitogenic and antiapoptotic genes in acute myeloid leukemia (AML) cells. We examined the antileukemic properties of a novel MNK inhibitor, SEL201. Our studies provide evidence that SEL201 suppresses eIF4E phosphorylation on Ser209 in AML cell lines and in primary patient-derived AML cells. Such effects lead to growth inhibitory effects and leukemic cell apoptosis, as well as suppression of leukemic progenitor colony formation. Combination of SEL201 with 5’-azacytidine or rapamycin results in synergistic inhibition of AML cell growth. Collectively, these results suggest that SEL201 has significant antileukemic activity and further underscore the relevance of the MNK pathway in leukemogenesis.

Introduction: Venetoclax (VEN), a novel BCL-2 inhibitor, received accelerated FDA approval for the treatment of newly diagnosed (ND) acute myeloid leukemia (AML) in adults aged 75 years or older, or who have comorbidities precluding use of intensive chemotherapy, in combination with hypomethylating agents (HMAs: azacitidine [AZA] or decitabine [DEC]), or low-dose cytarabine (LDAC). As Phase III trials have demonstrated relative efficacy of VEN combinations, this real-world initiative provides insight into the characteristics and outcomes of ND AML patients (pts) treated with VEN combinations vs non-VEN-based regimens in clinical practice. Methods: The AML Real world evidenCe (ARC) Initiative is a multicenter chart review study of adult pts with ND AML treated with VEN ≥ 4-11-2016 (VEN cohort) or non-VEN-based regimens ≥ 5-15-2015 (control cohort) from different academic sites in the US. Pts in the control cohort were matched to pts in the VEN cohort based on age ( Results: At time of interim data analysis, 33 VEN and 33 control ND AML pts were included. Combinations in the VEN cohort included HMA (AZA [26 pts, 78.8%], DEC [6 pts, 18.2%]) or LDAC (1 pt, 3.0%); the control cohort received high- (18 pts, 54.5%) or low-intensity regimens (15 pts, 45.5%; HMA: 12 pts; enasidenib: 2 pts; LDAC: 1 pt). Median age was 75 years in both VEN and control cohorts, 39.4% and 42.4% were female, respectively, and 63.6% had de novo AML in both cohorts. The majority had ECOG performance status of 1 (VEN: 66.7%; control: 63.3%) and adverse-risk ELN classification (66.7% in both cohorts). All pts with favorable-risk in the VEN cohort (100.0%) had mutated NPM1 without FLT3-ITD or with low allelic ratio ( In the high-intensity therapy matched subgroup (VEN: n=18; control: n=18), median age was 74 and 69 in VEN versus control, respectively. The majority of pts had ECOG performance status of 1 (VEN: 76.5%; control: 75.0%) and adverse-risk ELN classification (61.1% in both cohorts). High-intensity treatment regimens used for the control group were: CPX-351 (n=10; 55.6%), 7+3 (n=4; 22.2%), 7+3 + gemtuzumab ozogamicin (n=3; 16.7%), cytarabine + mitoxantrone (n=1; 5.6%). In the VEN matched high-intensity subgroup, 15 (83.3%) received VEN + AZA, 2 (11.1%) received VEN + DEC, and 1 (5.6%) received VEN + LDAC. Ten (55.6%) initiated VEN as an inpatient treatment. Outcomes for the full sample and subgroup are presented in Table 1. In the full sample, the overall response rate (ORR: CR+CRi+CRh) was 69.7% in the VEN cohort and 45.5% in the control cohort. The 1-year OS was 67.0% in the VEN cohort and 44.2% in the control cohort for the full sample; and 71.3% and 55.4%, respectively, in the high-intensity therapy matched subgroups. Conclusions: The ongoing ARC Initiative demonstrates real-world treatment effectiveness of VEN combinations in clinical practice. The real-world outcomes for VEN combinations for ND AML pts appear consistent with results reported from clinical trials, though a small number of pts were assessed. Further analyses of comparisons to matched controls, both overall and in the high-intensity therapy matched subgroup, and continuing data collection will allow a more robust assessment of the comparative effectiveness of VEN combinations in the real-world setting. Disclosures Pollyea: Syndax: Consultancy; Syros: Consultancy; Novartis: Consultancy; Karyopharm: Consultancy; Janssen: Consultancy; 47: Consultancy, Research Funding; Genentech: Consultancy; Takeda: Consultancy; Celgene/BMS: Consultancy; Agios: Consultancy; Glycomimetics: Other; Amgen: Consultancy; Abbvie: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Pfizer: Consultancy. Talati:BMS: Honoraria; Jazz: Speakers Bureau; AbbVie: Honoraria; Pfizer: Honoraria; Astellas: Speakers Bureau. Lai:Abbvie: Consultancy; Jazz: Speakers Bureau; Astellas: Speakers Bureau; Macrogenics: Consultancy; Agios: Consultancy. Abedin:Helsinn Healthcare: Honoraria; Agios: Honoraria; Jazz Pharmaceuticals: Honoraria; Pfizer: Research Funding; Helsinn Healthcare: Research Funding; Actinium Pharmaceuticals: Research Funding. Zeidner:Sumitomo Dainippon Pharma Oncology, Inc.: Research Funding; Merck: Research Funding; Forty-Seven: Other: Travel Reimbursement, Research Funding; AROG: Research Funding; AsystBio Laboratories: Consultancy; Daiichi Sankyo: Honoraria; Takeda: Consultancy, Honoraria, Other: Travel Reimbursement, Research Funding; Pfizer: Honoraria; Genentech: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; AbbVie: Honoraria, Other: Independent Review Committee; Agios: Honoraria. Xavier:Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Morphosys: Honoraria, Membership on an entity's Board of Directors or advisory committees; TG therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees; Acrotec: Consultancy, Speakers Bureau; Biegene: Speakers Bureau; Genentech: Speakers Bureau; Seattle Genetics: Speakers Bureau; Celgene/BMS: Speakers Bureau; Epizyme: Speakers Bureau; Astellas: Speakers Bureau; Incyte: Speakers Bureau. Wolach:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Fees for lectures and Consultancy, Research Funding; Pfizer: Consultancy, Honoraria; Janssen: Other: Fees for lectures and Consultancy; Amgen: Other: Fees for lectures and Consultancy; Astellas: Consultancy, Honoraria, Other: Fees for lectures and Consultancy; Novartis: Consultancy, Honoraria, Other: Fees for lectures and Consultancy. Moshe:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Lecturer; Astellas: Membership on an entity's Board of Directors or advisory committees, Other: lecturer; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Fee for lec. Choi:AbbVie: Current Employment, Current equity holder in publicly-traded company. Bui:AbbVie: Current Employment, Current equity holder in publicly-traded company. Svensson:AbbVie: Current Employment, Current equity holder in publicly-traded company. Kye:AbbVie: Current Employment, Other: may hold stock or other options. Burne:Analysis Group, Inc., which has received consultancy fees from AbbVie: Current Employment. Guerin:Abbvie: Consultancy, Other; Sanofi Genzyme: Consultancy, Other: Annie Guerin is an employee of Analysis Group, Inc. which received consultancy fees from Sanofi Genzyme.; Novartis Pharmaceuticals Corporation: Consultancy, Other: Annie Guerin is an employee of Analysis Group, Inc. which received consultancy fees from Novartis.. Ma:Genentech, Inc.: Current Employment, Current equity holder in publicly-traded company. Montez:Genentech, Inc.: Current Employment; F. Hoffmann-La Roche: Current equity holder in publicly-traded company. Goldberg:Dava Oncology: Honoraria; Pfizer: Research Funding; Celularity: Research Funding; AROG: Research Funding; Aprea: Research Funding; ADC Therapeutics: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aptose: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Aberrant activation of mTOR signaling in acute myeloid leukemia (AML) results in a survival advantage that promotes the malignant phenotype. To improve our understanding of factors that contribute to mammalian target of rapamycin (mTOR) signaling activation and identify novel therapeutic targets, we searched for unique interactors of mTOR complexes through proteomics analyses. We identify cyclin dependent kinase 9 (CDK9) as a novel binding partner of the mTOR complex scaffold protein, mLST8. Our studies demonstrate that CDK9 is present in distinct mTOR-like (CTOR) complexes in the cytoplasm and nucleus. In the nucleus, CDK9 binds to RAPTOR and mLST8, forming CTORC1, to promote transcription of genes important for leukemogenesis. In the cytoplasm, CDK9 binds to RICTOR, SIN1, and mLST8, forming CTORC2, and controls messenger RNA (mRNA) translation through phosphorylation of LARP1 and rpS6. Pharmacological targeting of CTORC complexes results in suppression of growth of primitive human AML progenitors in vitro and elicits strong antileukemic responses in AML xenografts in vivo.

The cure rate for several solid tumour malignancies including breast cancers, head and neck cancers, bone cancers, and sarcoma has improved remarkably with the advent of neoadjuvant and adjuvant therapies. Unfortunately, exposure to chemotherapy or radiation as a part of these treatments exposes patients to the risk of subsequent myeloid malignancies. Therapy related myeloid malignancies have certain characteristic findings. They typically arise within 10 years of treatment exposure, they are seen in younger patients, and the greatest risk is in patients who receive therapy with alkylating agents or topoisomerase II inhibitors. Solid tumours whose therapies utilize these agents at higher doses, namely bone/soft tissue cancers, testicular cancer, anal cancer, and brain tumours, appear to be the groups at highest risk for T-MN. Beyond these patients, emerging populations diagnosed with T-MN include prior platinum exposure, and patients requiring G-CSF support with chemotherapy.

We compared the outcomes of salvage chemotherapy in 146 patients with relapsed (57.5%) or refractory (42.5%) AML who received CLAG-M (51%), MEC (39%) or CLAG (10%). Minimal residual disease (MRD) was assessed by flow cytometry. Bivariate, Kaplan-Meier, and Cox regression analyses were conducted. Complete remission (CR) rate of 46% (CLAG-M 54% versus MEC/CLAG 40%

The full impact of the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), on the field of hematopoietic cell transplantation (HCT) is unknown. This perspective paper reviews the following: current COVID-19 epidemiology, diagnosis, and potential therapies; care considerations unique to HCT recipients; and the concept of a learning network to assimilate emerging guidelines and best practices and to optimize patient outcomes through facilitating shared learning and experience across transplantation centers.

Allogeneic transplantation represents a potentially curative procedure for various lethal conditions; however, it is associated with serious immune mediated complications. The most serious complication is graft-versus-host disease (GVHD). Acute GVHD (aGVHD) is unresponsive to initial corticosteroid therapy in ~40% of cases. Corticosteroid-refractory aGVHD (CR-aGVHD) represents a significant unmet need with nearly 60% mortality in patients developing this state.We review landmark trials which led to the US FDA approval of Ruxolitinb for the treatment of CR-aGVHD. Ruxolitinib phosphate is a Janus Kinase 1 and 2 inhibitor which inhibits pro-inflammatory signaling, and modulates T-cell subsets to an anti-inflammatory phenotype. Ruxolitinib was recently prospectively studied for the treatment of CR-aGVHD in the REACH1 trial, which added Ruxolitinib to corticosteroid therapy. This trial demonstrated favorable results with 73% of patients ultimately responding. Among responders, over 70% remained alive at 6 months. These results led to the US FDA to approve ruxolitinib as treatment for CR-aGVHD, the first approval of its kind.Ruxolitinib represents the standard option for CR-aGVHD. Future studies should identify patients less likely to respond to ruxolitinib and/or focus on a more targeted approaches to reduce infectious complications and cytopenias seen with this drug.

Introduction: Venetoclax (VEN) is a BCL-2 inhibitor FDA approved in combination with azacitidine (AZA), decitabine (DEC), or low-dose cytarabine (LDAC) for newly diagnosed (ND) acute myeloid leukemia (AML) in adults aged ≥75 or those with comorbidities precluding intensive chemotherapy. We explored real-world practices and clinical outcomes of patients (pts) treated with VEN-based vs. non-VEN-based regimens in the AML Real world evidenCe (ARC) Initiative. Methods: This multicenter chart review study includes adult pts with ND AML treated with VEN (VEN cohort) after 11 April 2016 matched to pts with non-VEN-based regimens (control cohort) after 15 May 2015 from 10 academic sites in the US and 4 in Israel. Pts were randomly selected and matched on age ( Results: Select results are shown in Table 1. 133 VEN and 133 control ND AML pts were included. Median age was 73 years (Range: 34-89) in the VEN cohort and 71 years (Range: 40-89) in the control cohort; 60.9% of matched pts were The mean duration of follow-up was 9.2 months in the VEN cohort and 14.6 months in the control cohort and the mean duration of treatment was 6.9 months and 4.3 months. Composite complete remission (CCR: CR+CRi) rate was 60.4% in the VEN cohort and 50.0% in the control cohort and rate of MLFS was 7.2% and 3.4%, respectively; among the pts who achieved a response (CR, CRi, CRh, or MLFS; 81 VEN and 68 control pts), median time to best response was 1.7 months and 1.3 months, respectively. The 1-year KM DOR for patients who achieved CCR was 57.7% in the VEN cohort and 53.1% in the control cohort. After initial therapy, 5.3% of pts in the VEN cohort and 15.0% of pts in the control cohort were referred to HCT. The 1-year KM OS was 62.6% in the VEN cohort and 49.8% in the control cohort and the 1-year KM EFS was 41.4% and 31.5%. In the Conclusions: The current analyses support real-world treatment effectiveness of VEN combinations and are consistent with data reported from clinical trials, despite the relatively short follow-up at the time of interim analyses. The outcomes, including OS at 1 year, for VEN combinations in ND AML pts appear similar to matched control pts, including the subgroup of pts Figure 1 Figure 1. Disclosures Garcia: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Pfizer: Research Funding; Prelude: Research Funding; AstraZeneca: Research Funding. Wolach: Neopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding. Vachhani: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees. Talati: Jazz: Speakers Bureau; BMS: Honoraria; Pfizer: Honoraria; AbbVie: Honoraria; Astellas: Speakers Bureau. Pollyea: Karyopharm: Consultancy; Syndax: Consultancy; Amgen: Consultancy; AbbVie: Consultancy, Research Funding; Novartis: Consultancy; Genentech: Consultancy; Janssen: Consultancy; Celgene/BMS: Consultancy; Pfizer: Consultancy; Takeda: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Glycomimetics: Other. Lai: Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Speakers Bureau; Macrogenics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Speakers Bureau; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees. Moshe: Astellas: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Lectures. Abedin: Astellas Pharma Inc.: Research Funding; Amgen: Honoraria; Pfizer: Research Funding; Actinium: Research Funding; AltruBio: Research Funding; Agios: Honoraria; Helsinn: Research Funding. Lavie: AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Fees for lectures; BMS: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Other: Fees for lectures; Roche: Other: Fees for lectures; Novartis: Other: Fees for lectures. Zuckerman: AbbVie: Honoraria; Orgenesis Inc.: Honoraria; BioSight Ltd: Honoraria; Janssen: Honoraria; Novartis: Honoraria; Gilead Sciences: Honoraria, Speakers Bureau; Cellect Biotechnology: Honoraria. Xavier: ADC Therapeutics: Speakers Bureau; Epizyme: Speakers Bureau; Celgene/BMS: Speakers Bureau; Seattle Genetics: Speakers Bureau; Morphosys/Incyte: Speakers Bureau; Beigene: Speakers Bureau; Acrotec: Consultancy; Genentech: Honoraria; Kite/Gilead: Honoraria; Jansen/Pharmacyclics: Honoraria; AstraZeneca: Honoraria, Speakers Bureau; Verastem: Honoraria; AbbVie: Consultancy, Speakers Bureau. Lee: AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bui: Abbvie: Current Employment, Other: May hold equity. Svensson: AbbVie: Current Employment, Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company. Burne: Analysis Group Inc: Current Employment, Other: Analysis Group Inc received consulting funds from AbbVie. Kye: AbbVie: Current Employment, Other: May hold equity. Maitland: Analysis Group Inc: Current Employment, Other: Analysis Group Inc received consulting funds from AbbVie. Ma: Genentech, Inc.: Current Employment, Other: May hold equity. Montez: Genentech, Inc: Current Employment, Other: May hold equity. Grunspan: AbbVie: Current Employment, Other: May hold equity. Goldberg: Aptose: Consultancy, Research Funding; Arog: Research Funding; Pfizer: Research Funding; Prelude Therapeutics: Research Funding; Aprea: Research Funding; Celularity: Research Funding; DAVA Oncology: Honoraria; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Background: Lintuzumab-Ac225 (Actimab-A) is a humanized CD33 antibody, lintuzumab, conjugated to an alpha emitting isotope, actinium (Ac225), with potent single agent activity against AML. We hypothesized that a low dose infusion of lintuzumab-Ac225, after salvage chemotherapy, would effectively eliminate residual leukemia and improve remission rates, and depth of remission. Patients and Methods: Adult patients with relapsed/refractory AML (RR-AML), and with adequate organ function and performance status were eligible for screening. On screening, we assessed CD33 expression, greater than 25% of leukemic blasts must have expressed CD33 antigen by flow cytometry for inclusion. Induction consisted of G-CSF, 300mcg/d, given D1-6, cladribine 5mg/m2, given D2-6, cytarabine 2g/m2, given D2-6, and mitoxantrone 10mg/m2, given D2-4. Lintuzumab-Ac225 was administered as a single dose on either day 7, 8, or 9. This trial enrolled to 4 cohorts, administering lintuzumab-ac225 at a dose of 0.25uCi/kg, 0.50uCi/kg, 0.75uCi/kg, and 1.0uCi/kg. Treatment consisted of one induction cycle. Disease assessment, including MRD assessment by flow, was performed between Days 29-42. Results: Sixteen patients with a median age of 64 yrs were evaluable for toxicity and response. Three pts were treated in cohort 1 (0.25uCi/kg), nine pts were treated in cohort 2 (0.5uCi/kg), three pts were treated in cohort 3 (0.75uCi/kg), and one pt was treated in cohort 4 (1.0uCi/kg). Patient characteristics include 63% (n=10) pts with adverse cytogenetics, mutations involving TP53 in 44% (n=7) pts, and secondary/therapy-related AML in 50% (n=8) of patients. Patients received a median 2 lines of therapy, and 50% (n=8) received a venetoclax combination regimen prior to enrollment. Table 1 summarizes patient characteristics. No undue non-hematologic toxicities were observed in this trial. Commonest AEs were neutropenic fever and infection. Among responders, an ANC>1000 was achieved in 9/10 patients, at a median of 33 days, and a platelet count >50k was achieved in 6/10 patients at a median of 37 days. Of note, two patients proceeded to HCT prior to platelet recovery. Overall, among patients enrolled in cohorts 1-3, CR/CRi was observed in 67% (n=10) pts. One patient enrolled in cohort 4 achieved an aplastic marrow by D+42, with subsequent stem cell boost and neutrophil recovery. Of responders, 70% (7/10) had no measurable disease (MRD(-)) by flow cytometry. Among patients receiving Conclusions: Lintuzumab-Ac225 at a low dose appears to be safe in combination with the salvage chemotherapy regimen CLAG-M. Furthermore, this combination has demonstrated promising efficacy results among high risk RR-AML patients, namely patients with adverse molecular/cytogenetic features and patients previously receiving venetoclax. Updated Cohort 4 results will be presented at ASH. Upon determination of MTD, we plan to explore the combination of lintuzumab-Ac225 with other salvage regimens (e.g. FLAG, FLAG-Ida, MEC) to determine whether adding this novel agent can generally improve salvage outcomes in hard to treat patients. Figure 1 Figure 1. Disclosures Abedin: Helsinn: Research Funding; Agios: Honoraria; AltruBio: Research Funding; Pfizer: Research Funding; Amgen: Honoraria; Actinium: Research Funding; Astellas Pharma Inc.: Research Funding. Guru Murthy: Guidepoint: Consultancy; Cancerexpertnow: Honoraria; Techspert: Consultancy; Qessential: Consultancy; Cardinal Health Inc.: Honoraria; TG therapeutics: Other: Advisory board. Hamadani: Sanofi, Genzyme, AstraZeneca, BeiGene: Speakers Bureau; Takeda, Spectrum Pharmaceuticals and Astellas Pharma: Research Funding; Janssen, Incyte, ADC Therapeutics, Omeros, Morphosys, Kite: Consultancy. Atallah: Pfizer: Consultancy, Research Funding; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Abbvie: Consultancy, Speakers Bureau; Amgen: Consultancy; Novartis: Consultancy, Honoraria, Research Funding.

Background: Mcl-1 is an anti-apoptotic protein in the Bcl-2 family that contributes to the pathophysiology of certain B-cell malignancies and AML. Dependence on Mcl-1 is associated with poor prognosis, and increased Mcl-1 levels is a common mechanism of resistance to venetoclax. Voruciclib (VORU), a potent oral CDK9 inhibitor (Ki Methods: Pts with relapsed B-cell lymphoma, chronic lymphocytic leukemia (CLL), or AML were eligible if age ≥18 years, ECOG performance status ≤1, disease progression after failure of standard therapies, adequate hepatic and renal function, and no prior CDK9 therapy. Dose escalation started at 50 mg, followed a 3+3 design, and DLTs were assessed in Cycle 1. Initially VORU was administered once daily continuously in a 28-day cycle (Group I). After 2 DLTs were observed at 100 mg, administration was changed to once daily on days 1 to 14 in a 28-day cycle (Group II), patients with prior allogeneic transplant were excluded, and dose escalation (100, 150, 200 mg) proceeded in separate cohorts for AML and B-cell malignancies. Disease response was assessed by the Lugano, iwCLL, and 2017 ELN criteria. Results: To date 28 pts have been enrolled: 14 AML, 7 diffuse large B-cell lymphoma (DLBCL), 3 follicular lymphoma (FL), 2 CLL and 2 mantle cell lymphoma. Group I enrolled 16 pts, 8 each at 50 mg and 100 mg. Group II enrolled 12 pts, 10 with AML administered VORU at 100, 150 or 200 mg and 2 pts with B-cell malignancies administered VORU at 100 mg. Dose escalation in AML is completed. Median age was 71 years (range 40-90) and 54% of pts were male. Pts were generally heavily pretreated, with a median of 3 prior therapies (range 1-8). Median number of VORU cycles administered was 2 (range 1-4). Drug-related serious adverse events (SAEs) were reported in Group I only and consisted of 2 DLT of Gr 3 pneumonitis at 100 mg, both in AML pts treated with allogeneic transplant followed by GVHD in the preceding 12 months, one of whom also had a concurrent Gr 3 differentiation syndrome (DS), and 1 SAE not meeting DLT criteria, a Gr 3 hypoxemic respiratory failure in Cycle 4 in a pt with DLBCL at 50 mg. One AML pt developed ischemic bowel thought to be due to disease progression. Symptoms consistent with DS were observed in 4 AML pts. In Group II, no DLTs have been observed to date and there were no Gr 3-5 drug-related adverse events reported. There is no evidence of significant drug-related neutropenia in pts with B-cell malignancies. To date, in Groups I and II combined, 1 AML pt achieved a morphologic leukemia-free state, 2 AML pts achieved stable disease (SD), and 3 pts with B-cell malignancies had a best response of SD, including 1 FL pt who achieved a 42% reduction in SPD, and 1 CLL pt with relapsed disease after chemoimmunotherapy, venetoclax, and ibrutinib who had stable blood counts. Conclusions: VORU at doses up to 200 mg administered on 14 consecutive days in a 28-day cycle was well tolerated with no DLTs observed. Consistent with the phase 1 studies in solid tumors, no significant myelosuppression was seen in pts with B-cell malignancies. The safety profile does not indicate overlapping toxicities with venetoclax. Disease stabilization was observed in heavily pretreated pts and differentiation syndrome was observed in AML indicating biologic activity. Enrollment at 200 mg will continue in an expansion cohort in AML. A forthcoming protocol amendment will evaluate VORU in combination with venetoclax in pts with relapsed AML to exploit the dual inhibition of Bcl-2 and Mcl-1. Disclosures Konopleva: Sanofi: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; KisoJi: Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Stemline Therapeutics: Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; AstraZeneca: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Cellectis: Other: grant support; Forty Seven: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. Brander: Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; BeiGene: Research Funding; DTRM: Research Funding; Genentech: Consultancy, Research Funding; Juno Therapeutics/Celgene/Bristol Myers Squibb: Research Funding; Pfizer: Consultancy, Other: Biosimilars outcomes research panel; TG Therapeutics: Consultancy, Research Funding; Ascentage: Research Funding; LOXO: Research Funding; AstraZeneca: Research Funding; MEI Pharma: Research Funding; ArQule: Research Funding; AbbVie: Consultancy, Other: informCLL registry steering committee, Research Funding; Verastem: Consultancy; Novartis: Research Funding; NCCN: Other: panel member; ArQule/Merck: Consultancy. Patel: TG Therapeutics: Consultancy, Speakers Bureau; Curis, Inc: Research Funding; Xencor: Research Funding; Kite: Consultancy, Research Funding, Speakers Bureau; Genentech/Roche: Consultancy, Research Funding, Speakers Bureau; Juno Pharmaceuticals: Consultancy; Fate Therapeutics: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding, Speakers Bureau; MEI Pharma: Consultancy, Research Funding; Trillium Therapeutics: Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Morphosys: Consultancy; Abbvie: Consultancy; Aptevo Therapeutics: Research Funding; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Sunesis Pharmaceuticals: Research Funding; Pharmacyclics/Janssen: Consultancy, Research Funding, Speakers Bureau; Velos Bio: Research Funding; Millenium/Takeda: Research Funding. Diefenbach: Celgene: Research Funding; Trillium: Research Funding; IMab: Research Funding; Merck Sharp & Dohme: Consultancy, Honoraria, Research Funding; Morphosys: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Incyte: Research Funding; Gilead: Current equity holder in publicly-traded company; AbbVie: Research Funding; Perlmutter Cancer Center at NYU Langone Health: Current Employment; IGM Biosciences: Research Funding; MEI: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Genentech, Inc./ F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding. Alvarado: BerGenBio: Research Funding; MEI Pharma: Research Funding; CytomX Therapeutics: Consultancy; Astex Pharmaceuticals: Research Funding; Jazz Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; FibroGen: Research Funding; Sun Pharma: Consultancy, Research Funding. Al Malki: Rigel Pharma: Consultancy; Neximmune: Consultancy; Jazz Pharmaceuticals, Inc.: Consultancy; Hansa Biopharma: Consultancy; CareDx: Consultancy. Danilov: Bayer Oncology: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Honoraria, Research Funding; Takeda Oncology: Research Funding; TG Therapeutics: Consultancy, Research Funding; Abbvie: Consultancy, Honoraria; SecuraBio: Research Funding; Astra Zeneca: Consultancy, Honoraria, Research Funding; Rigel Pharm: Honoraria; Bristol-Meyers-Squibb: Honoraria, Research Funding; Gilead Sciences: Research Funding; Pharmacyclics: Consultancy, Honoraria; Beigene: Consultancy, Honoraria. Abedin: Pfizer: Research Funding; Amgen: Honoraria; Helsinn: Research Funding; Astellas Pharma Inc.: Research Funding; Agios: Honoraria; Actinium: Research Funding; AltruBio: Research Funding. Ghalie: MEI Pharma: Current Employment, Current equity holder in publicly-traded company. Davids: Genentech: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Astra-Zeneca: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; MEI Pharma: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding; Ascentage Pharma: Consultancy, Research Funding; TG Therapeutics: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; Surface Oncology: Research Funding; AbbVie: Consultancy; Adaptive Biotechnologies: Consultancy; BeiGene: Consultancy; Celgene: Consultancy; Eli Lilly and Company: Consultancy; Janssen: Consultancy; MEI Pharma: Consultancy; Merck: Consultancy; Research to Practice: Consultancy; Takeda: Consultancy. OffLabel Disclosure: Vorucicilb is an investigational CDK inhibitor being evaluated in patients with hematologic malignancies, specifically relapsed AML and B-cell malignancies. The abstract submitted to ASH 2021 reports the results of the completed dose escalation portion of a phase 1 study.

Background: Outcomes of adults with relapsed/refractory T-cell acute lymphoblastic leukemia or lymphoma (T-ALL or T-LBL respectively) and acute myeloid leukemia (AML) have remained poor despite the availability of newer agents. CD38 is a 45 kDa transmembrane glycoprotein expressed by lymphoid and myeloid cells with several important functions including a role in immune escape from tumor cells [Chillemi A et al. Front Immunol 2017, Furano A et al. J Immunol 1990]. Several studies have demonstrated that CD38 is expressed in tumor cells of patients with T-ALL and AML and potentially targetable using CD38 blocking agents [Naik J et al. Haematologica 2019, Bride KL et al. Blood 2018, Tembhare et al. J Immunother Cancer 2020, Farber M et al. ASH 2018]. XmAb18968 is structurally distinct CD3-CD38 bi-specific T-cell engager with a full fragment crystallizable (Fc) domain modified to minimize Fcγ receptor binding and non-selective activation of T cells and other immune effector cells. XmAb18968 has optimized relative affinities for both CD3 and CD38 which results in reduced cytokine release without compromising target cell killing. We hypothesize targeting CD38 in relapsed/refractory- T-cell ALL/LBL and AML is safe and feasible using XmAb18968, a novel CD3-CD38 bispecific antibody. Study design and methods: This is an investigator-sponsored multi-institutional phase I study evaluating the safety and tolerability of XmAb18968. Patients aged 18 years or above with T-ALL, T-LBL or AML (including undifferentiated leukemia and bi phenotypic leukemia), in relapsed/refractory status (at least one line of prior therapy) including measurable residual disease relapse, CD38 expression ≥ 20%, and adequate organ function will be eligible. Major exclusion criteria are hematopoietic cell transplantation (HCT) within 6 months of enrollment, active acute GVHD, veno-occlusive disease, and acute promyelocytic leukemia. The study is planned to be conducted at 6 sites in United States. The primary endpoint is to determine the recommended phase 2 dose (RP2D) and toxicity profile of XmAb18968. The secondary endpoints include determination of response rates, duration of response, survival and pharmacokinetics. Exploratory endpoints include correlation of responses with genomic profile, assessment of serum cytokine response, identifying the changes in phenotypic expression of activated T-cells and leukemic cells, correlation of the phenotypic expression with changes in the transcriptome at the single-cell level, proteomics evaluation of cytokine secretion at the single-cell level and correlation of response with N-glycan profiling, quantitative site-occupancy and direct glycopeptide analysis. The study will follow 3+3 design for dose escalation and de-escalation in case of dose limiting toxicity (DLT). Dose escalation will proceed in two separate groups: Group A for subjects with T-ALL and T-LBL and Group B for subjects with AML. Patients will be entered sequentially to each dose level, starting with the first dose level. The DLT observation period for dose-escalation will be 28-days. RP2D will be defined as the highest dose level at which none of the first 3 treated subjects, or no more than 1 of the first 6 treated subjects experience a DLT. A minimum of 24 and a maximum of 60 patients will be needed for the dose escalation phase. Disclosures Guru Murthy: Curio Sciences: Honoraria; Techspert: Consultancy; Qessential: Honoraria; CancerExpertNow: Honoraria; DAVA Oncology: Honoraria; TG Therapeutics: Other: Advisory board meeting; Cardinal health: Honoraria; Guidepoint: Consultancy. Johnson: Miltenyi Biotec: Research Funding. Abedin: AltruBio: Research Funding; Amgen: Honoraria; Agios: Honoraria; Helsinn: Research Funding; Pfizer: Research Funding; Astellas Pharma Inc.: Research Funding; Actinium: Research Funding. Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Shah: Precision Biosciences: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Acrotech/Spectrum: Honoraria; BeiGene: Consultancy, Honoraria; Amgen: Consultancy; Pfizer: Consultancy, Other: Expenses; Novartis: Consultancy, Other: Expenses; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; Adaptive Biotechnologies: Consultancy; Servier Genetics: Other; Jazz Pharmaceuticals: Research Funding; Incyte: Research Funding. Leonard: Amgen: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees. Pratz: Agios: Consultancy; BMS: Consultancy, Honoraria; Novartis: Consultancy; Astellas: Consultancy, Honoraria, Research Funding; Cellgene: Consultancy, Honoraria; Millenium: Research Funding; University of Pennsylvania: Current Employment; Abbvie: Consultancy, Honoraria, Research Funding. Luger: Syros: Honoraria; Agios: Honoraria; Daiichi Sankyo: Honoraria; Jazz Pharmaceuticals: Honoraria; Brystol Myers Squibb: Honoraria; Acceleron: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Onconova: Research Funding; Celgene: Research Funding; Biosight: Research Funding; Hoffman LaRoche: Research Funding; Kura: Research Funding. Badar: Pfizer Hematology-Oncology: Membership on an entity's Board of Directors or advisory committees. Atallah: Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy; Abbvie: Consultancy, Speakers Bureau; Takeda: Consultancy, Research Funding; BMS: Honoraria, Speakers Bureau; Pfizer: Consultancy, Research Funding.

Introduction: Venetoclax (VEN) is a novel BCL-2 inhibitor indicated in the US for treatment of newly-diagnosed (ND) acute myeloid leukemia (AML) in adults ≥75 years or with comorbidities precluding use of intensive chemotherapy, in combination with azacitidine (AZA), decitabine (DEC), or low-dose cytarabine (LDAC). Despite widespread clinical use of VEN combinations in ND AML, real-world practice patterns are largely unknown. We set out to explore real-world outcomes and treatment paradigms in ND AML patients treated with VEN-based regimens. Methods: The AML Real world evidenCe (ARC) Initiative is a multicenter chart review study of adult pts with ND AML treated with VEN-based regimens and matched control pts (by age and ELN risk) from different academic sites in the US (10 sites) and Israel (4 sites), assessing real-world outcomes as well as VEN treatment practices. Interim descriptive results with data cutoff of 17 May 2021 are presented; data collection is ongoing, with a targeted sample size of over 250 VEN pts and further global expansion planned. Descriptive results are presented here on VEN-related treatment practices overall, and separately in the US and Israel. Results: At data cutoff, 133 VEN ND AML pts were included. The majority of pts were treated at US sites (102 pts, 76.7%). Regimens administered were VEN+AZA (106 pts, 79.7%), VEN+DEC (24 pts, 18.0%), and VEN+LDAC (3 pts, 2.3%). In Israel, all pts were treated with VEN+AZA (31 pts, 100.0%). Median age was 73.2 years, and the majority of pts (64.7%) had adverse ELN risk. Common genetic mutations observed included TP53 (30 pts, 22.7%), RUNX1 (21 pts,15.9%), IDH1/IDH2 (22 pts, 16.5%), NPM1 (15 pts, 11.4%), and FLT3 ITD (12 pts, 9.1%). Mean [median] duration of follow-up was 9.2 months [7.1] and duration of VEN-based treatment was 6.9 months [4.1]. 27.8% of pts had discontinued VEN. Among those who discontinued (37 pts), reasons for discontinuation included intolerance (13/37 pts, 35.1%), relapse (8/37 pts, 21.6%), and insufficient response (7/37 pts, 18.9%; results not shown). Unplanned dose interruptions during therapy were observed for 40 pts (30.1%) with common reasons including severe febrile neutropenia (13/40 pts, 32.5%), neutropenia (severe: 10/40 pts, 25.0%; non-severe: 5/40 pts, 12.5%), and patient request (6/40 pts, 15.0%). Venetoclax ramp-up was performed for 74.4% of pts overall and was more common in Israel (29 pts, 93.5%) than US sites (70 pts 68.6%). Among pts with venetoclax ramp-up performed, the majority received initial VEN treatment in the inpatient setting (US: 47/70 pts, 67.1%; Israel: 25/29 pts 86.2%), median starting and ending doses were 100mg and 400mg respectively, and median ramp-up duration was 3 days; which was similar in the US and Israel. Antifungal use during the first cycle, either prophylactically or in response to an infection, was observed in two-thirds of pts (88 pts, 66.2%) and was more common in the US (72 pts, 70.6%). Among pts with prophylactic antifungal use of a strong CYP3A4 inhibitor (33 pts, 24.8%), 42.4% of pts did not ramp-up and started and maintained a venetoclax dose of 100mg. At data cutoff, 120 pts had laboratory testing and bone marrow assessment results available in the full sample. Of these pts, timing of first bone marrow biopsy assessments varied, with 44.5% of pts having an assessment in their first cycle of venetoclax and 11.8% of pts having an assessment after the first two cycles. In Israel, a higher proportion of pts had a bone marrow assessment during their first cycle of venetoclax (18 pts, 58.1%). Out of those with response assessed (111 pts, 90.2%), 65.8% of pts achieved a response of CR, CRh, or CRi (US: 54/86 pts, 62.8%; Israel: 19/25 pts, 76.0%). Conclusions: The ongoing ARC Initiative provides insights on real-world treatment practices and management of ND AML pts treated with VEN-based regimens from academic sites. The ramp-up and dosing patterns appear consistent with label, with some variation. Delay in timing of bone marrow assessments may affect the assessment of time to response and post-response management in the real-world. Additional data collection in the ARC Initiative will provide more robust and valuable insights into VEN-based treatment practices and management in the real world. Figure 1 Figure 1. Disclosures Vachhani: Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wolach: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Neopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Garcia: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Research Funding; Pfizer: Research Funding; Prelude: Research Funding; AstraZeneca: Research Funding. Talati: Pfizer: Honoraria; AbbVie: Honoraria; BMS: Honoraria; Jazz: Speakers Bureau; Astellas: Speakers Bureau. Pollyea: Takeda: Consultancy; Daiichi Sankyo: Consultancy; Syndax: Consultancy; Karyopharm: Consultancy; Novartis: Consultancy; AbbVie: Consultancy, Research Funding; Agios: Consultancy; Glycomimetics: Other; Amgen: Consultancy; Janssen: Consultancy; Genentech: Consultancy; Celgene/BMS: Consultancy; Pfizer: Consultancy. Lai: Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Speakers Bureau; Jazz Pharma: Speakers Bureau; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees. Moshe: Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; Astellas: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Lectures. Abedin: Agios: Honoraria; Actinium: Research Funding; AltruBio: Research Funding; Helsinn: Research Funding; Pfizer: Research Funding; Amgen: Honoraria; Astellas Pharma Inc.: Research Funding. Lavie: AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Fees for lectures; BMS: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Fees for lectures; Roche: Other: Fees for lectures; Novartis: Other: Fees for lectures; Takeda: Consultancy. Zuckerman: Cellect Biotechnology: Honoraria; Gilead Sciences: Honoraria, Speakers Bureau; Novartis: Honoraria; Janssen: Honoraria; BioSight Ltd: Honoraria; Orgenesis Inc.: Honoraria; AbbVie: Honoraria. Xavier: AbbVie: Consultancy, Speakers Bureau; Morphosys/Incyte: Speakers Bureau; Jansen/Pharmacyclics: Honoraria; ADC Therapeutics: Speakers Bureau; Epizyme: Speakers Bureau; Genentech: Honoraria; Kite/Gilead: Honoraria; Beigene: Speakers Bureau; Acrotec: Consultancy; Seattle Genetics: Speakers Bureau; AstraZeneca: Honoraria, Speakers Bureau; Verastem: Honoraria; Celgene/BMS: Speakers Bureau. Lee: Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bui: Abbvie: Current Employment, Other: May hold equity. Svensson: AbbVie: Current Employment, Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company. Kye: AbbVie: Current Employment, Other: May hold equity. Burne: Analysis Group Inc: Current Employment, Other: Analysis Group Inc received consulting funds from AbbVie. Maitland: Analysis Group Inc: Current Employment, Other: Analysis Group Inc received consulting funds from AbbVie. Ma: Genentech, Inc.: Current Employment, Other: May hold equity. Montez: Genentech, Inc: Current Employment, Other: May hold equity. Grunspan: AbbVie: Current Employment, Other: May hold equity. Goldberg: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Arog: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Research Funding; Aptose: Consultancy, Research Funding; Aprea: Research Funding; DAVA Oncology: Honoraria; Celularity: Research Funding; Prelude Therapeutics: Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Background : Gilteritinib, an oral FMS-like tyrosine kinase 3 (FLT3) inhibitor, is approved for the treatment of adults with FLT3-mutated (FLT3mut+) relapsed or refractory (R/R) acute myeloid leukemia (AML) in the United States and many other countries/regions. However, not all respond to treatment and most patients eventually develop recurrent disease. Combining gilteritinib with other agents may improve response. Atezolizumab (840 mg intravenous [IV] every 2 weeks [Q2W]) + azacitidine demonstrated an overall response rate of 62% in hypomethylating agent-naive patients with higher-risk myelodysplastic syndrome (Gerds AT, et al. Blood. 2018;132[suppl 1]:466). Therefore, the safety and efficacy of combination therapy with gilteritinib and atezolizumab was investigated in an ongoing phase 1, open-label, single-arm, dose-escalation study (ClinicalTrials.gov identifier: NCT03730012) in adult patients with FLT3mut+ R/R AML. Methods : This phase 1 dose-escalation study enrolled adults with FLT3mut+ AML and Eastern Cooperative Oncology Group performance status of ≤2 who were refractory to ≥1 cycle of induction chemotherapy or relapsed after achieving remission with a prior therapy. Key exclusion criteria included AML secondary to prior chemotherapy for other neoplasms (except for myelodysplastic syndrome) and patients who have relapsed after allogeneic hematopoietic stem cell transplantation. Patients received gilteritinib 120 mg/day combined with atezolizumab 420 mg or 840 mg via IV infusion Q2W in 28-day cycles. Herein, we present safety and tolerability (dose-limiting toxicities [DLT] and treatment-emergent adverse events [TEAE]; primary end points). Decisions regarding DLTs and recommended phase 2 dose are determined by a dose evaluation committee. Composite complete remission (CRc) rate (primary end point), best response rate (secondary end point), and gilteritinib trough plasma concentrations (C trough; secondary end point) were also evaluated. Results : As of 13 June 2021, 3 patients received gilteritinib 120 mg/day + atezolizumab 420 mg Q2W (cohort 1) and 8 patients received gilteritinib 120 mg/day + atezolizumab 840 mg Q2W (cohort 2). Median (range) age was 82.0 (68-84) and 66.5 (20-87) years in cohorts 1 and 2, respectively. No patients received prior second-generation FLT3 inhibitor therapy. The median duration of gilteritinib exposure was 107.0 and 49.5 days in cohorts 1 and 2, respectively. Seven patients received ≥2 cycles of atezolizumab. No DLTs were reported in cohort 1; 2 patients (25%) reported DLTs in cohort 2 (1 occurrence each of increased alanine aminotransferase and encephalopathy). The most common TEAEs (≥30%) across both cohorts were febrile neutropenia (72.7%); fatigue (54.5%); dyspnea, muscular weakness, and decreased platelet count (45.5% each); and anemia, decreased appetite, diarrhea, dizziness, epistaxis, fall, and pyrexia (36.4% each; Table). Serious TEAEs were reported in 10 patients (91.0%). Treatment-related adverse events (TRAEs) were reported in 10 patients (90.9%), of which 9 patients (81.8%) reported serious TRAEs (only event reported in >1 patient was febrile neutropenia [54.5%]). Study treatment was withdrawn for 8 patients (72.7%) due to TEAEs, of which TEAEs were considered TRAEs in 6 patients (54.5%). TEAEs lead to death in 3 patients (27.3%). Efficacy results will be provided at the time of presentation. Pharmacokinetic analyses suggested that C trough of gilteritinib in combination with atezolizumab (420 mg or 840 mg Q2W) was similar to single-agent gilteritinib in patients with R/R AML. Cohorts 1 and 2 showed similar gilteritinib C trough values. Conclusions: In this phase 1 dose-escalation study, the combination of gilteritinib and atezolizumab had an acceptable safety profile with no new safety signals identified for either agent. Owing to a strategic decision, the expansion phase of the study will not be conducted. The combinatorial prospect of gilteritinib observed in this study supports future studies of gilteritinib combination therapy. Figure 1 Figure 1. Disclosures Altman: Kuro Oncology: Consultancy; Syros: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; AbbVie: Consultancy; Glycomimetics: Membership on an entity's Board of Directors or advisory committees; BioSight: Consultancy, Other: Travel fees to attend an advisory meeting (I did not accept payment for the advisory board); Theradex: Consultancy. Bhatnagar: Sumitomo Dainippon Pharma: Research Funding; Novartis: Honoraria; Karyopharm Therapeutics Inc.: Honoraria, Research Funding; Astellas: Honoraria; Pfizer: Honoraria; Kite: Honoraria; Cell Therapeutics: Honoraria, Research Funding; Celgene: Honoraria. Abedin: Agios: Honoraria; AltruBio: Research Funding; Actinium: Research Funding; Amgen: Honoraria; Helsinn: Research Funding; Pfizer: Research Funding; Astellas Pharma Inc.: Research Funding. Przespolewski: Jazz: Research Funding. Schiller: Agios: Consultancy, Research Funding, Speakers Bureau; Kaiser Permanente: Consultancy; Leukemia & Lymphoma Society: Research Funding; Bio: Research Funding; Tolero: Research Funding; Forma: Research Funding; Takeda: Research Funding; Delta-Fly: Research Funding; Actuate: Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Elevate: Research Funding; Deciphera: Research Funding; Cyclacel: Research Funding; MedImmune: Research Funding; Johnson & Johnson: Current equity holder in publicly-traded company; Genentech-Roche: Research Funding; Gamida Cell Ltd.: Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Eli Lilly: Research Funding; Actinium Pharmaceuticals, Inc: Research Funding; Abbvie: Research Funding; Arog: Research Funding; Biomed Valley Discoveries: Research Funding; Pharma: Consultancy; ASH foundation: Other: Chair-unpaid; Novartis: Consultancy, Research Funding; Sellas: Research Funding; Regimmune: Research Funding; PrECOG: Research Funding; Samus: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Onconova: Research Funding; Sangamo: Research Funding; Mateon: Research Funding; Karyopharm: Research Funding; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; FujiFilm: Research Funding; Ambit: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Geron: Research Funding; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Trovagene: Research Funding; Ono-UK: Consultancy, Research Funding; Ono: Consultancy; Incyte: Consultancy; Ariad: Research Funding; AstraZeneca: Consultancy; Daiichi-Sankyo: Research Funding; Constellation Pharmaceuticals: Research Funding; Celator: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Astellas: Honoraria, Research Funding, Speakers Bureau; Bluebird Bio: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Gill: Astellas Pharma Global Development: Current Employment. Patel: Astellas Pharma Global Development: Current Employment. Fan: Astellas Pharma Global Development: Current Employment. Tiu: Astellas Pharma Global Development: Current Employment. Strickland: Sunesis: Research Funding; AbbVie: Other: Advisory Board; ArcherDx: Other: Advisory Board; Astellas: Other: Advisory Board; Genentech: Other: Advisory Board; Incyte: Other: Advisory Board; Jazz: Other: Advisory Board; Kite: Other: Advisory Board; Kura Oncology: Other: Advisory Board; Novartis: Other: Advisory Board; Pfizer: Other: Advisory Board; Syros: Other: Advisory Board. OffLabel Disclosure: New indication for atezolizumab

Background: Outcomes of patients with relapsed/refractory AML (RR-AML) have remained poor. Therapy with venetoclax based combinations in this setting leads to CR/CRi rates of 21-49% (DiNardo CD et al. Am J Hematol 2018, Aldoss I et al. Haematologica 2018, Stahl M et al. Blood Adv 2020). Preclinical studies with BCL-2 inhibitors indicate potential mechanisms of drug resistance including overexpression of the anti-apoptotic protein MCL-1 (Konopleva et al. Cancer Cell. 2006). Pevonedistat is a first in class inhibitor of Nedd8 activating enzyme that induces the pro-apoptotic protein NOXA leading to neutralization of MCL-1 and apoptosis. Preclinical studies evaluating the combination of pevonedistat and venetoclax against AML cell lines have demonstrated a synergistic effect (Knorr KL et al. Cell Death Differ. 2015). Hence, we designed a phase I study to assess the safety and tolerability of adding pevonedistat to the combination of azacitidine and venetoclax in patients with RR-AML. Study design and methods: We conducted a phase I study with the combination of pevonedistat, venetoclax and azacitidine in patients with RR-AML. Patients aged 18 years or above with morphologically documented RR-AML, ECOG performance status 0-2 and adequate organ function were eligible. Major exclusion criteria were isolated extramedullary relapse, hematopoietic cell transplantation (HCT) within 100 days of enrollment, and active acute GVHD. Previous therapy with hypomethylating agents (HMA) or venetoclax was not an exclusion criterion. The dose escalation phase was conducted using 3+3 design. Treatment included azacitidine (75 mg/m 2 daily x 7 days), venetoclax (400 mg daily x 28 days), and pevonedistat in escalating doses (10-20 mg/m 2 IV days 1,3,5 of each cycle) with a cycle length of 28 days. Pevonedistat was given at 10 mg/m 2 dose in cohort 1, 15 mg/m 2 dose in cohort 2 and 20 mg/m 2 dose in cohort 3. The primary endpoint is to determine the recommended phase 2 dose (RP2D) and toxicity profile of pevonedistat, azacitidine and venetoclax. Other endpoints included determination of response rates, duration of response, survival, pharmacokinetics, correlation of response rates with AML genomic profile, correlation of pretreatment levels of BCL2, BCLXL, MCL1, BAX or BAK with response, determination of changes in NOXA (PMAIP1) mRNA and protein expression pre-and post-pevonedistat treatment, evaluation of BH3 mimetic profiling on bone marrow samples by flow cytometry and assessing the sensitivity of leukemia and leukemic stem/progenitor cells to pevonedistat ex vivo. Results: Thirteen patients participated in the dose escalation phase, 12 of whom were evaluable. Median age was 69 years (61-91), 30.8% had secondary/therapy related AML, 69.2% with adverse risk disease, 53.8% previously received venetoclax/HMA and 23.1% had relapse after prior allogeneic hematopoietic cell transplantation (HCT) (Table 1). Seven patients were enrolled into cohort 1 (pevonedistat 10 mg/m 2 dose) of which one was not evaluable, three patients enrolled into cohort 2 (pevonedistat 15 mg/m 2 dose), and three patients enrolled into cohort 3 (pevonedistat 20 mg/m 2 dose). Grade 3 or higher AEs included febrile neutropenia (23%), infection (15%), anemia (38%), neutropenia (54%), thrombocytopenia (38%). There was 1 dose limiting toxicity (DLT) in cohort 1 (atrial fibrillation) that triggered cohort expansion. However, subsequent patients did not experience DLT despite planned dose escalation. Of the 12 evaluable total patients, CR/CRi was observed in 5 (41.6%) patients. Notably, patients with RR-AML who were venetoclax/HMA naïve had a CR/CRi 83.3% (5/6 patients). The response rates for each cohort are summarized in Table 2. Three of the five patients with CR/CRi (60%) achieved MRD negativity by flow cytometry. Four patients who achieved CR/CRi proceeded to allogeneic HCT after therapy. Median OS of the cohort was 5.4 months (1.8-14) and median OS was not reached in patients with CR/CRi. Conclusions: The addition of pevonedistat to venetoclax and azacitidine backbone is safe and well tolerated in patients with RR-AML. Dose escalation yielded encouraging efficacy in venetoclax/HMA naïve RR-AML patients. The study is currently in the dose expansion phase. Details on correlative studies examining mechanisms of therapeutic efficacy and resistance will be reported in the main meeting. Figure 1 Figure 1. Disclosures Guru Murthy: Cardinal health: Honoraria; TG Therapeutics: Other: Advisory board meeting; DAVA Oncology: Honoraria; CancerExpertNow: Honoraria; Qessential: Honoraria; Techspert: Consultancy; Curio Sciences: Honoraria; Guidepoint: Consultancy. Abedin: AltruBio: Research Funding; Helsinn: Research Funding; Amgen: Honoraria; Pfizer: Research Funding; Agios: Honoraria; Actinium: Research Funding; Astellas Pharma Inc.: Research Funding. Litzow: Jazz: Other: Advisory Board; Pluristem: Research Funding; Actinium: Research Funding; Amgen: Research Funding; Astellas: Research Funding; AbbVie: Research Funding; Omeros: Other: Advisory Board; Biosight: Other: Data monitoring committee. Atallah: Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Research Funding; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Abbvie: Consultancy, Speakers Bureau; Amgen: Consultancy.

Background: Primary and secondary [post-essential thrombocythemia (ET) or polycythemia vera (PV)] Myelofibrosis (MF) are clonal hematopoietic neoplasms marked by constitutive JAK-STAT activation, bone marrow fibrosis, cytopenias, and constitutional symptom burden. Allogeneic hematopoietic cell transplantation (HCT) is the only curative option in this disease. Median overall survival (OS) after JAK inhibitor (JAKi) discontinuation is poor, ranging from 6-24 months (Harrision et al. Ann Hematol. 2020). Haploidentical (Haplo)-HCT with post-transplant cyclophosphamide (PTCy) has improved donor availability, but data on post-HCT outcomes in MF remain scarce. Herein, we describe clinical outcomes of patients (pts) with MF who underwent haplo-HCT with PTCy. Methods: We conducted a multi-institutional study where we retrospectively reviewed charts to obtain pt, disease, and treatment characteristics of MF pts who underwent haplo-HCT from 2000 to 2019. Graft-versus-host-disease (GVHD), relapse, and non-relapse mortality (NRM) were described as cumulative incidences. OS and relapse free survival (RFS) were estimated using the Kaplan-Meier method. Univariate analyses were conducted with Cox or Fine and Gray regression. Results: Fifty-eight adult pts from 11 centers underwent haplo-HCT and were included in the analysis. Pt, disease, and HCT characteristics are listed in Table 1. Thirty-four (59%) pts were over 60 years of age at the time of HCT. Of the 53 pts in whom driver mutation data was available, JAK2 was reported in 34 (64%), CALR in 10 (19%), MPL in 4 (8%), and 5 (9%) were triple-negative. Twenty-two (38%) pts had HCT-CI ≥ 3. Median CD34+ cell dose was 6.81 (range: 2.3-28.6) x 106/kg. All pts received PTCy as a part of GVHD prophylaxis regimen. Median follow-up in this study was 28 (range: 3.3-75.7) months. Neutrophil and platelet engraftment was reported in 53 (91%) and 47 (81%) pts at a median time of 20 (range: 14-70) and 31 (range: 15-225) days, respectively. Five pts (9%) had graft failure. The cumulative incidences of all-grade acute and chronic GVHD were in 44% (95% CI: 31-56%) at 6 months and 31% (95% CI: 18-44%) at 2 years. Grade 3-4 acute GVHD was seen in 5 (9%) pts. Post-HCT relapse/disease persistence occurred in 12 (21%) pts with a median of 416 (range: 28-917) days. The 2-year estimates of OS, RFS, relapse and NRM were 69% (95% CI: 55-80%), 52% (95% CI: 37-65%), 21% (95% CI: 11-34%) and 27% (95% CI: 16-39%) respectively (Fig 1). On univariate analyses (Table 2), older age (HR 2.17, P=.012) and a higher HCT-CI (HR 1.4, P Conclusions: Based on this study, we conclude that haplo-HCT with PTCy is a valid option in pts with MF. The graft failure rates appear to be similar to those reported with sibling and unrelated donors. Older age, higher HCT-CI and bone marrow as graft source were associated with inferior outcomes. JAKi use prior to HCT or type of driver mutation did not significantly affect outcomes. Disclosures Grunwald: Trovagene: Consultancy; Daiichi Sankyo: Consultancy; Merck: Consultancy; Agios: Consultancy; Janssen: Research Funding; Cardinal Health: Consultancy; Incyte: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Forma Therapeutics: Research Funding; Amgen: Consultancy; Celgene: Consultancy; Incyte: Consultancy, Research Funding; Celgene: Consultancy; Celgene: Consultancy; Pfizer: Consultancy; Incyte: Consultancy, Research Funding; Merck: Research Funding; Astellas: Consultancy; Genentech/Roche: Research Funding; Premier: Consultancy; Premier: Consultancy; Astellas: Consultancy; Premier: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Abbvie: Consultancy; Merck: Consultancy; Pfizer: Consultancy; Trovagene: Consultancy; Trovagene: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Agios: Consultancy; Forma Therapeutics: Research Funding; Forma Therapeutics: Research Funding; Astellas: Consultancy; Amgen: Consultancy; Amgen: Consultancy; Merck: Consultancy; Cardinal Health: Consultancy; Pfizer: Consultancy; Cardinal Health: Consultancy; Janssen: Research Funding; Genentech/Roche: Research Funding; Genentech/Roche: Research Funding. Dholaria:J&J: Research Funding; Takeda: Research Funding; Angiocrine: Research Funding; bms: Research Funding; Poseida: Research Funding. Abedin:Jazz Pharmaceuticals: Honoraria; Agios: Honoraria; Helsinn Healthcare: Honoraria; Pfizer: Research Funding; Helsinn Healthcare: Research Funding; Actinium Pharmaceuticals: Research Funding. Gupta:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy; Incyte: Honoraria, Research Funding; Bristol MyersSquibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees. DeZern:MEI: Consultancy; Celgene: Consultancy, Honoraria; Astex: Research Funding; Abbvie: Consultancy. Gerds:Sierra Oncology: Research Funding; Pfizer: Research Funding; Celgene: Consultancy, Research Funding; CTI Biopharma: Consultancy, Research Funding; AstraZeneca/MedImmune: Consultancy; Incyte Corporation: Consultancy, Research Funding; Apexx Oncology: Consultancy; Roche/Genentech: Research Funding; Imago Biosciences: Research Funding; Gilead Sciences: Research Funding. Jain:Bristol Myer Squibb: Other: for advisory board participation; Takeda: Consultancy, Honoraria; CareDx: Other: Advisory Board.

Background: Lintuzumab Ac225 is a radiolabeled anti-CD33 antibody, composed of an alpha emitting isotope, Ac225, conjugated with the humanized anti-CD33 monoclonal antibody lintuzumab. As monotherapy, lintuzumab Ac225 was studied as upfront therapy for unfit AML, and nearly 70% of pts achieved a CR/CRi at the highest dose level (2uCi/kg) without significant non-hematologic toxicity. Therefore, we hypothesized that lintuzumab Ac225, when added to the salvage chemotherapy regimen CLAG-M (cladribine, cytarabine, G-CSF, and mitoxantrone), would be tolerable and would improve remission rates in the treatment of relapsed/refractory AML (RR-AML). This investigator-initiated phase I study is the first study to combine radioimmunotherapy with salvage chemotherapy in pts with RR-AML. Patients and Methods: Medically fit pts with RR-AML, aged 18 years and older were eligible. Eligibility also required that more than 25% of leukemic blasts must have been CD33 positive by flow cytometry. Induction consisted of G-CSF, 300mcg/d, given D1-6, cladribine 5mg/m2, given D2-6, cytarabine 2g/m2, given D2-6, and mitoxantrone 10mg/m2, given D2-4. Lintuzumab Ac225 was administered as a single dose on either day 7, 8, or 9. This trial had three cohorts, administering lintuzumab Ac225 at a dose of 0.25uCi/kg, 0.50uCi/kg, or 0.75uCi/kg. Treatment consisted of one induction cycle, with subsequent therapy up to physician discretion. Results: Fifteen pts were evaluable, with a median age of 61 yrs (Figure 1). Slightly less than half of the pts had previously received venetoclax/HMA and slightly more than half had previously had allogeneic HCT. Three pts enrolled into cohort 1 (0.25uCi/kg), nine pts enrolled into cohort 2 (0.5uCi/kg), and three pts enrolled into cohort 3 (0.75uCi/kg). Grade 3 or greater AEs irrespective of causality included febrile neutropenia (n=12), infection (n=8), maculopapular rash (n=2), nausea (n=2), and one patient each with QTc prolongation and tumor lysis syndrome. Of 15 pts, CR/CRi was observed in 10 (67%) pts. Excluding pts receiving >3 prior lines of therapy, 10/12 (83%) achieved CR/CRi. In cohort 1, 1 patient (33%) achieved remission (1 CR). In cohort 2, 6 pts (67%) achieved remission (3 CR, 2 CRp, 1 CRi). In cohort 3, 3 pts (100%) achieved remission (1 CR, 2 CRp). 7 pts of the 10 with CR/CRi (70%) achieved MRD negativity by flow (Table 2). Two of the 3 patients in cohort 3 were MRD- after therapy and the third had a small number of AML cells detected (0.2%). All pts who were independent for platelet transfusions pre-treatment recovered platelets. Overall, median time to ANC recovery ≥500 was 33 days, and median time to platelet recovery ≥50k was 35 days. 6 pts proceeded to allogeneic HCT after therapy. Conclusion: We conclude that lintuzumab Ac225 in combination with CLAG-M chemotherapy has a clinically acceptable safety profile. Dose escalation yielded highly encouraging efficacy results for RR-AML. With acceptable safety at 0.75uCi/kg, we have amended this protocol to study a 4th dose level at 1.0uCi/kg. Overall, this regimen represents a safe and potentially effective therapy for medically fit RR-AML pts, particularly as a bridge to allogeneic HCT. Disclosures Abedin: Helsinn Healthcare: Honoraria; Actinium Pharmaceuticals: Research Funding; Helsinn Healthcare: Research Funding; Pfizer: Research Funding; Jazz Pharmaceuticals: Honoraria; Agios: Honoraria. Hamadani:Takeda Pharmaceutical Company; Spectrum Pharmaceuticals; Astellas Pharma: Research Funding; ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Janssen R&D; Incyte Corporation; ADC Therapeutics; Celgene Corporation; Pharmacyclics, Omeros, AbGenomics, Verastem, TeneoBio: Consultancy; Sanofi Genzyme, AstraZeneca: Speakers Bureau. Michaelis:Jazz Pharmaceuticals: Research Funding. Atallah:Abbvie: Consultancy; Genentech: Consultancy; Jazz: Consultancy; Pfizer: Consultancy; Takeda: Consultancy, Research Funding; Novartis Pharmaceutical Corporation: Consultancy.

Key Points CMML patients comprise an elderly and frail patient population with comorbidities that often require surgical intervention. Postsurgical leukemoid reaction, a life-threatening complication in CMML patients, may be driven by molecular mechanisms.

Outcomes of acute promyelocytic leukemia (APL) have significantly improved with the availability of targeted agents. It remains unclear whether the population-level outcomes of APL have improved over time.Using the SEER database, we identified patients aged ≥20 years with pathologically confirmed APL diagnosed in 2000 through 2014 and who were actively followed. Patients were stratified by diagnosis period into 3 groups (2000-2004, 2005-2009, and 2010-2014) to assess the temporal trends in overall survival (OS), cause-specific survival (CSS), and other outcomes.A total of 2,962 patients with a median age of 48 years (range, 20-96 years) were included. Hispanic patients constituted 21.5% of the cohort and the largest proportion (47.9%) of uninsured patients. The incidence of APL was 0.33 cases per 100,000 population per year. Incidence varied significantly by age, sex, race/ethnicity, and diagnosis period. Survival was significantly higher for patients diagnosed in 2010 through 2014 compared with those diagnosed in 2005 through 2009 and in 2000 through 2004 (4-year OS, 73.4% vs 65.6% vs 57.3%, respectively; 4-year CSS, 78.3% vs 70.8% vs 60.8%, respectively). Early mortality improved significantly over time (2000-2004, 25.3%; 2005-2009, 20.6%; 2010-2014, 17.1%) and was higher in men and Hispanic patients. According to multivariate analysis, diagnosis before 2010 and unmarried status were associated with a higher mortality risk. Uninsured patients had a significantly higher early mortality without a significant difference in post-30-day CSS. No significant changes were noted in risk of secondary malignancies.Population-level outcomes of APL have continued to improve over time. However, significant discrepancies in disease outcomes continue to exist, highlighting the need for more research.

Corticosteroid-refractory graft-versus-host disease (SR-GVHD) remains a significant source of morbidity after allogeneic hematopoietic cell transplantation. No standard therapy exists in this setting; however, recent studies have demonstrated a very promising role for ruxolitinib, an oral Janus kinase 1/2 inhibitor. With increasing evidence of efficacy for SR-GVHD, limited data exist describing complications of ruxolitinib use, specifically infectious complications during use in SR-GVHD. In this study we report outcomes and infectious complications at our institution with ruxolitinib use. Overall, 43 patients were treated with ruxolitinib for SR-GVHD, 19 for acute SR-GVHD and 24 for chronic SR-GVHD. With respect to acute SR-GVHD, 15 patients had grade III acute GVHD and 4 patients had grade IV acute GVHD. At 28 days, a response rate of 84% was detected. With respect to chronic SR-GVHD, 16 patients had moderate refractory disease and 8 had severe refractory disease. At around 28 days, a 63% response rate was detected. Overall, 42% of patients (n = 18) treated with ruxolitinib had a documented infectious event. Infectious events were significantly more common among patients treated for acute SR-GVHD (P.005). Among patients treated for acute SR-GVHD, both viral (n = 11) and bacterial (n = 10) events were frequently encountered. Cytomegalovirus reactivation was detected in 4 patients without organ involvement in any patient. Bacteremia was the most common bacterial event (n = 8), and 2 patients died after development of bacteremia. Only 5 of 24 patients treated with ruxolitinib for chronic SR-GVHD developed infectious complications after initiation of therapy. Nearly an even number of viral (n = 3) and bacterial (n = 4) were detected. This study supports the use of ruxolitinib in SR-GVHD, with impressive responses observed in both acute and chronic SR-GVHD. Infectious complications were particularly frequent among patients treated for acute SR-GVHD, and nearly all these patients were concurrently on high-dose steroids while on ruxolitinib. This study suggests careful monitoring for viral reactivation is required for patients initiated on ruxolitinib, supports the role of continuing prophylactic antimicrobial measures in ruxolitinib-treated GVHD patients, and raises the question of whether bacterial prophylaxis should be considered among patients initiated on ruxolitinib for acute SR-GVHD, particularly while on high-dose steroids.

T-cell acute lymphoblastic leukemia (T-ALL) is a curable malignancy in the pediatric population. However, population-level data on its incidence and outcomes among adults is sparse. Using SEER database, we identified 1141 patients aged ≥20 years with pathologically confirmed T-ALL diagnosed between the years 2001 and 2014 and actively followed. Incidence of T-ALL was 0.13 cases/100,000 population with significant variations by age, gender, race, and period. The 5-year overall survival (OS) declined significantly with increasing age (age40, 51.9%; age 40-59, 37.3%; age 60-79, 19.2%; age ≥80, 0%; p .001) and varied by race (whites - 45.7%, blacks - 25.1%, others - 40.3%; p .001). Over time, OS has improved significantly in patients60 years (2001-2007, 42.8% vs 2008-2014, 53.1%; p = .005), but not in patients older than 60 years (2001-2007, 18% vs 2008-2014, 22.8%; p = .71), highlighting the need for effective and safe treatments in this population.

Allogeneic hematopoietic cell transplantation (allo-HCT) with reduced-intensity conditioning (RIC) is commonly performed as an inpatient procedure. The feasibility and outcomes of RIC allo-HCT in the outpatient setting is not known. We performed a single-center retrospective cohort study of patients aged ≥ 18years with hematologic malignancies who underwent RIC allo-HCT either in the inpatient or outpatient setting. Donor types included HLA-matched sibling and well-matched unrelated donors. The objectives were to compare the survival, complications, charges, and incidences of relapse, nonrelapse mortality (NRM), and acute and chronic graft-versus-host disease (GVHD) between the 2 groups. Between 2014 and 2017, 151 eligible patients were included, with 116 undergoing RIC allo-HCT in the inpatient setting and 35 patients undergoing RIC allo-HCT in the outpatient setting. Baseline characteristics were comparable between the 2 groups except for a higher proportion of patients with myeloma in the outpatient cohort (inpatient 15.5% versus outpatient 37.1%). The cumulative incidence of grades II to IV acute GVHD (inpatient 25.2% versus outpatient 25.7%), grades III to IV acute GVHD (inpatient 10.4% versus outpatient 8.5%), chronic GVHD (inpatient 38.3% versus outpatient 51.6%), NRM at 1 year (inpatient 10.8% versus outpatient 3.2%), and relapse (inpatient 24.8% versus outpatient 33.2%) did not significantly differ between the 2 cohorts. One-year progression-free survival (inpatient 64.4% versus outpatient 63.6%, P = .39) and overall survival (inpatient 73.8% versus outpatient 82.8%, P = .93) were also not significantly different between the 2 groups. The proportion of patients who developed neutropenic fever (inpatient 25.8% versus outpatient 8.5%, P = .03) and mucositis (inpatient 50.8% versus outpatient 8.5%, P.001) and who required total parenteral nutrition (inpatient 20.6% versus outpatient 5.7%, P = .04) were more frequent in the inpatient cohort. About 51.5% of the outpatient cohort never required hospital admission in the first 100days. Outpatient HCT resulted in significantly lower charges than inpatient HCT in the first 100days (median charges: inpatient $339,621 versus outpatient $247,334; P.001). On multivariate analysis the site of the HCT (outpatient versus inpatient) was not a significant predictor of either overall or progression-free survival. Outpatient RIC allo-HCT is feasible and safe with daily outpatient evaluation and aggressive supportive care resulting in outcomes comparable with those who received the transplant in the inpatient setting.

The bromodomain and extra-terminal (BET) family of proteins are important epigenetic regulators involved in promoting gene expression of critical oncogenes. BET inhibitors have been demonstrated to repress c-Myc expression, and were initially shown to have efficacy in a number of c-Myc-dependent hematologic malignancies. Recent studies have now revealed a broader role for BET inhibitors in hematologic malignancies. In this review, we summarize the efficacy of BET inhibitors in preclinical models of acute leukemia, lymphoma, and multiple myeloma. We also summarize recent results of clinical trials utilizing BET inhibitors in hematologic malignancies, characterize potential resistance mechanisms to BET inhibitors, and discuss potential combination therapies with BET inhibitors in patients with hematologic malignancies.

Aims Evaluate pharmacokinetic (PK) profile of Eftozanermin alfa (ABBV-621; eftoza) as monotherapy (eftoza-mono) or eftoza and venetoclax (eftoza-VEN); assess safety and tolerability, preliminary antitumor activity, and exploratory biomarkers. Methods In this phase 1 study, adults with relapsed/refractory (RR) acute myeloid leukemia (AML) or diffuse large B-cell lymphoma (DLBCL) received intravenous eftoza, 1.25, 3.75, or 7.5 mg/kg in AML eftoza-mono and 3.75 or 7.5 mg/kg in AML and DLBCL eftoza-VEN cohorts days 1, 8, and 15 of a 21-day cycle. VEN dose was 400 mg or 800 mg daily (oral). Results As of September 2019, 34 patients enrolled: 4 in AML eftoza-mono(median age 75 yrs; 1.25 [n=1], 3.75 [n=1], or 7.5 [n=2] mg/kg eftoza), 19 in AML eftoza-VEN(median age 72 yrs; 3.75 [n=10] or 7.5 [n=9] mg/kg eftoza), and 11 in DLBCL eftoza-VEN cohorts (median age 64 yrs; 3.75 [n=3] or 7.5 [n=8] mg/kg eftoza). Patients received eftoza for median 1 (AML eftoza-mono), 3 (AML eftoza-VEN), and 2 (DLBCL eftoza-VEN) cycles. Four patients in AML eftoza-VEN cohorts completed ≥5 cycles. Percentage of patients with treatment-emergent adverse events (TEAEs) was 100% for AML eftoza-mono/VEN, and 91% for DLBCL eftoza-VEN. Grade ≥3 TEAEs were in all AML eftoza-mono/VEN patients and 27% in DLBCL eftoza-VEN. Most common grade ≥3 TEAEs were increased alanine (n=4, AML eftoza-VEN) and aspartate (n=4, AML eftoza-VEN; n=1, DLBCL eftoza-VEN) aminotransferase. Serious eftoza-related AEs were in 5 patients (AML eftoza-VEN); none in >1 patient. Eftoza exhibited dose-proportional kinetics at weekly 1.25- to 7.5-mg/kg doses; PK was not affected by VEN. No responses were seen in AML eftoza-mono or DLBCL eftoza-VEN cohorts. Overall response rate in AML eftoza-VEN cohorts was 4/19 (21%), with 3 complete responses (CR; 3.75 mg/kg [n=2], 7.5 mg/kg [n=1]), and 1 CR with incomplete hematologic recovery (7.5 mg/kg); 4 had RD (3.75 mg/kg [n=2], 7.5 mg/kg [n=2]) and 3 PD (3.75 mg/kg [n=3]). Eftoza binding to death receptors on neutrophils was saturated by 2h post-dose in AML and DLBCL cohorts. There was time-dependent desaturation of the receptors for eftoza binding. In 63% of patients with RR AML ≥3, molecular aberrations were observed, with IDH1/2 and RAS being the most frequently mutated genes. Conclusions Eftoza-mono and eftoza-VEN were tolerated in patients with RR AML and DLBCL. Antitumor activity was observed in patients with AML treated with eftoza-VEN at 3.75- or 7.5-mg/kg doses. Abstract was previously published at EHA25.

Prognosis for patients with AML remains dismal. Despite multiple clinical trials across several decades, little improvement for the therapy of non-APL AML was noted. However, over the last couple of years, several new therapies have demonstrated efficacy in the therapy of patients with AML. Several of those have been approved by the FDA for AML therapy. These include CPX-351, midostaurin, gemtuzumab ozogamicin, enasidenib and ivosidenib. Our goal in this review is to summarize currently available data on these new therapies and discuss the rapidly evolving treatment landscape of AML.