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The randomized, placebo-controlled, phase 3 QUAZAR AML-001 trial (ClinicalTrials.gov identifier: NCT01757535) evaluated oral azacitidine (Oral-AZA) in patients with acute myeloid leukemia (AML) in first remission after intensive chemotherapy (IC) who were not candidates for hematopoietic stem cell transplantation. Eligible patients were randomized 1:1 to Oral-AZA 300 mg or placebo for 14 days per 28-day cycle. We evaluated relapse-free survival (RFS) and overall survival (OS) in patient subgroups defined by NPM1 and FLT3 mutational status at AML diagnosis and whether survival outcomes in these subgroups were influenced by presence of post-IC measurable residual disease (MRD). Gene mutations at diagnosis were collected from patient case report forms; MRD was determined centrally by multiparameter flow cytometry. Overall, 469 of 472 randomized patients (99.4%) had available mutational data; 137 patients (29.2%) had NPM1 mutations (NPM1mut), 66 patients (14.1%) had FLT3 mutations (FLT3mut; with internal tandem duplications [ITD], tyrosine kinase domain mutations [TKDmut], or both), and 30 patients (6.4%) had NPM1mut and FLT3-ITD at diagnosis. Among patients with NPM1mut, OS and RFS were improved with Oral-AZA by 37% (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.41-0.98) and 45% (HR, 0.55; 95% CI, 0.35-0.84), respectively, vs placebo. Median OS was improved numerically with Oral-AZA among patients with NPM1mut whether without MRD (48.6 months vs 31.4 months with placebo) or with MRD (46.1 months vs 10.0 months with placebo) post-IC. Among patients with FLT3mut, Oral-AZA improved OS and RFS by 37% (HR, 0.63; 95% CI, 0.35-1.12) and 49% (HR, 0.51; 95% CI, 0.27-0.95), respectively, vs placebo. Median OS with Oral-AZA vs placebo was 28.2 months vs 16.2 months, respectively, for patients with FLT3mut and without MRD and 24.0 months vs 8.0 months for patients with FLT3mut and MRD. In multivariate analyses, Oral-AZA significantly improved survival independent of NPM1 or FLT3 mutational status, cytogenetic risk, or post-IC MRD status.

Mutations in the nucleophosmin 1 gene (NPM1) occur frequently in acute myeloid leukemia (AML) and are associated with a favorable prognosis. Applying the new 2022 European LeukemiaNet (ELN) classifier, Angenendt et al tested the prognostic significance of the copresence of NPM1 mutations and adverse-risk cytogenetics among 2426 patients. The authors demonstrate that outcomes for cytogenetic adverse-risk AML are not modulated by the presence or absence of NPM1 mutations, thereby clarifying management for patients.

Myelodysplastic syndromes/neoplasms (MDS) are associated with variable clinical presentations and outcomes. The initial response criteria developed by the International Working Group (IWG) in 2000 have been used in clinical practice, clinical trials, regulatory reviews, and drug labels. While the IWG criteria were revised in 2006 and 2018 (the latter focusing on lower-risk disease), limitations persist in their application to higher-risk MDS and in their ability to fully capture clinical benefits of novel investigational drugs or to serve as valid surrogates for longer-term clinical endpoints (e.g., overall survival). Further, issues related to ambiguity and practicality of some criteria lead to variability in interpretation and inter-observer inconsistency in reporting results from the same sets of data. Thus, we convened an international panel of 36 MDS experts and used an established modified Delphi process to develop consensus recommendations for updated response criteria that would be more reflective of patient-centered and clinically relevant outcomes in higher-risk MDS. Among others, the IWG 2023 criteria include changes in the hemoglobin threshold for complete remission (CR), the introduction of CR with limited count recovery (CRL) and CR with partial hematologic recovery (CRh) as provisional response criteria, elimination of marrow CR, and specific recommendations for standardization of time-to-event endpoints and the derivation and reporting of responses. The updated criteria should lead to better correlation between patient-centered outcomes and clinical trial results in an era of multiple emerging new agents with novel mechanisms of action.

The BCL2 inhibitor venetoclax has established therapeutic roles in chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). As BCL2 is an important determinant of survival of both myeloid progenitor and B cells, we investigated whether clinical and molecular abnormalities arise in the myeloid compartment during long-term continuous venetoclax treatment of CLL in 89 patients (87 with relapsed/refractory CLL). Over a median follow-up of 75 (range 21-98) months, persistent cytopenias (≥1 of neutropenia, thrombocytopenia, anemia) lasting ≥4 months and unrelated to CLL occurred in 25 patients (28%). Of these patients, 20 (80%) displayed clonal hematopoiesis, including 10 with therapy-related myeloid neoplasms (t-MNs). t-MNs occurred exclusively in patients previously exposed to fludarabine-alkylator combination therapy with a cumulative 5-year incidence of 10.4% after venetoclax initiation, consistent with rates reported for patients exposed to fludarabine-alkylator combination therapy without venetoclax. To determine whether the altered myelopoiesis reflected the acquisition of mutations, we analyzed samples from patients with no or minimal bone marrow CLL burden (n = 41). Mutations in the apoptosis effector BAX were identified in 32% (13/41). In cellular assays, C-terminal BAX mutants abrogated outer mitochondrial membrane localization of BAX and engendered resistance to venetoclax killing. BAX-mutated clonal hematopoiesis occurred independently of prior fludarabine-alkylator combination therapy exposure and was not associated with t-MNs. Single-cell sequencing revealed clonal co-occurrence of mutations in BAX with DNMT3A or ASXL1. We also observed simultaneous BCL2 mutations within CLL cells and BAX mutations in the myeloid compartment of the same patients, indicating lineage-specific adaptation to venetoclax therapy.

BCL2 and MCL1 are commonly expressed prosurvival (antiapoptotic) proteins in hematologic cancers and play important roles in their biology either through dysregulation or by virtue of intrinsic importance to the cell-of-origin of the malignancy. A new class of small-molecule anticancer drugs, BH3 mimetics, now enable specific targeting of these proteins in patients. BH3 mimetics act by inhibiting the prosurvival BCL2 proteins to enable the activation of BAX and BAK, apoptosis effectors that permeabilize the outer mitochondrial membrane, triggering apoptosis directly in many cells and sensitizing others to cell death when combined with other antineoplastic drugs. Venetoclax, a specific inhibitor of BCL2, is the first approved in class, demonstrating striking single agent activity in chronic lymphocytic leukemia and in other lymphoid neoplasms, as well as activity against acute myeloid leukemia (AML), especially when used in combination. Key insights from the venetoclax experience include that responses occur rapidly, with major activity as monotherapy proving to be the best indicator for success in combination regimens. This emphasizes the importance of adequate single-agent studies for drugs in this class. Furthermore, secondary resistance is common with long-term exposure and often mediated by genetic or adaptive changes in the apoptotic pathway, suggesting that BH3 mimetics are better suited to limited duration, rather than continuous, therapy. The success of venetoclax has inspired development of BH3 mimetics targeting MCL1. Despite promising preclinical activity against MYC-driven lymphomas, myeloma, and AML, their success may particularly depend on their tolerability profile given physiological roles for MCL1 in several nonhematologic tissues.

BACKGROUND: IDH2 mutations occur in 8-19% of patients (pts) with AML. ENA is an oral, selective IDH2 inhibitor and AZA is a hypomethylating agent. In a phase 1b/2 trial, combination therapy with ENA + SC AZA significantly improved overall response rate (ORR) and complete remission (CR) rate vs AZA monotherapy (AZA-only) (P = 0.0064 and P = 0.0001, respectively) in pts with newly diagnosed (ND), mutant-IDH2 (m IDH2) AML not eligible for IC (DiNardo, 2020). Injectable AZA has shown to maintain pt-reported health-related quality of life (HRQoL) in ND-AML (Dombret, 2014); the effect of ENA on HRQoL has not been reported. While morphologic responses are associated with improved HRQoL, combining active agents could increase toxicity, which could diminish HRQoL. OBJECTIVE: Assess pt-reported HRQoL outcomes during treatment (Tx) with ENA + AZA and AZA-only in the phase 1b/2 AG-221-AML-005 trial (NCT02677922). METHODS: Adult pts with ECOG PS ≤ 2 and intermediate- or poor-risk cytogenetics were enrolled. In the phase 2 portion, pts were randomized 2:1 to ENA 100-mg QD (continuous) + AZA 75 mg/m 2/day (d) SC × 7d, or to AZA-only, in repeated 28d cycles (C). Pt-reported HRQoL was assessed during Tx using the EORTC QLQ-C30 and EQ-5D-5L instruments, each completed at baseline (BL [C1D1]), on d1 of each Tx cycle, and end of Tx (EOT). The primary HRQoL measures were observed mean changes from BL (CFB) in 5 QLQ-C30 domains-Global Health status (GHS)/QoL, Physical Functioning (PF), Role Functioning (RF), Fatigue, and Dyspnea-each scored from 0-100, with higher scores indicating better QoL or functioning but worse symptomology. Changes in the remaining 10 QLQ-C30 domains, and in the EQ-5D-5L utility index (UI) score (derived via cross-walk to EQ-5D-3L based on UK population weights) and EQ-5D visual analogue scale (VAS) score (0-100) were secondary outcomes. Changes are reported for Tx cycles with ≥ 10 evaluable pts in each Tx arm. Clinically meaningful changes were defined as mean CFB of ≥ 10 points on any QLQ-C30 domain, ≥ 0.08 point on the EQ-5D-5L UI, and ≥ 7 points on the EQ-5D VAS. HRQoL-evaluable pts had an evaluable assessment (≥ 15 items on the QLQ-C30; all 5 EQ-5D-5L items; non-missing EQ-5D VAS) at BL and at ≥ 1 post-BL visit. RESULTS: The HRQoL-evaluable population comprised ~75% of pts randomized to either ENA+AZA (51/68) or AZA-only (25/33); 25 pts were not evaluable due to missing data at BL (n = 16) and/or no post-BL visit (n = 19). QLQ-C30 data were missing for ~20%-30% of eligible pts at almost all post-BL visits through C9D1 (the last visit with ≥ 10 pts in each Tx arm), and for ≥ 50% of pts at the EOT visit; similar rates were observed on the EQ-5D-5L. BL characteristics for HRQoL-evaluable pts were generally comparable between arms and similar to those of the ITT population. At BL, mean QLQ-C30 scores in each Tx arm were meaningfully worse than general population normative scores across the majority of QLQ-C30 domains, including all 5 domains of primary interest, and on the EQ-5D VAS. During early ENA+AZA Tx cycles, observed mean QLQ-C30 scores remained similar to BL in the GHS/QoL and Dyspnea domains, and were worsened from BL in the PF, RF, and Fatigue domains-but reached the threshold for meaningful worsening only in the RF domain and only at C3D1 (Figure). Domain scores then trended toward improvement over time, with clinically meaningful improvements from BL from C4-C9 in the Dyspnea domain, C5-C9 in the GHS/QoL and Fatigue domains (except at C7 for Fatigue), and from C8-C9 in the RF domain; mean scores also improved from BL in the PF domain but were not clinically meaningful at any visit. Similar trends were observed in the AZA-only arm but without the early worsening seen with ENA+AZA (Figure). There were no clinically meaningful or statistically significant differences between Tx arms in mean CFB for any of the primary QLQ-C30 domains through C9. In both Tx arms, mean score CFB in the secondary QLQ-C30 domains, EQ-5D-5L UI, and EQ-5D VAS followed similar trends of improvement over time among pts who remained on Tx. CONCLUSIONS: At BL, these pts with AML reported meaningfully worse HRQoL scores across the majority of the QLQ-C30 domains and the EQ-5D VAS compared with the general population, indicating substantial impairment in HRQoL, functioning, and symptoms. HRQoL scores generally worsened during early ENA+AZA Tx cycles, but then improved with continued Tx, with meaningful improvement across multiple measures during later Tx cycles. Figure 1 Figure 1. Disclosures DiNardo: Agios/Servier: Consultancy, Honoraria, Research Funding; Foghorn: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Forma: Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding; Novartis: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; Takeda: Honoraria; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria, Research Funding. Dohner: Pfizer: Research Funding; Roche: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; GEMoaB: Honoraria; Janssen: Honoraria; Helsinn: Honoraria; Gilead: Honoraria; Berlin-Chemie: Honoraria; Astex Pharmaceuticals: Honoraria; Astellas: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Agios: Honoraria, Research Funding; AstraZeneca: Honoraria; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Oxford Biomedica: Honoraria; Abbvie: Honoraria, Research Funding. Zeidan: Agios: Consultancy; AstraZeneca: Consultancy; BioCryst: Other: Clinical Trial Committees; Daiichi Sankyo: Consultancy; Genentech: Consultancy; Cardiff Oncology: Consultancy, Other: Travel support, Research Funding; Incyte: Consultancy, Research Funding; Janssen: Consultancy; Novartis: Consultancy, Other: Clinical Trial Committees, Travel support, Research Funding; Pfizer: Other: Travel support, Research Funding; Amgen: Consultancy, Research Funding; Ionis: Consultancy; Gilead: Consultancy, Other: Clinical Trial Committees; Astellas: Consultancy; BMS: Consultancy, Other: Clinical Trial Committees, Research Funding; Geron: Other: Clinical Trial Committees; Acceleron: Consultancy, Research Funding; Loxo Oncology: Consultancy, Other: Clinical Trial Committees; Kura: Consultancy, Other: Clinical Trial Committees; Boehringer Ingelheim: Consultancy, Research Funding; Aprea: Consultancy, Research Funding; Jasper: Consultancy; Epizyme: Consultancy; Jazz: Consultancy; ADC Therapeutics: Research Funding; BeyondSpring: Consultancy; Astex: Research Funding; AbbVie: Consultancy, Other: Clinical Trial Committees, Research Funding. Schuh: Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GlycoMimetics: Research Funding; Kite/Gilead: Research Funding; Jazz: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Teva: Honoraria, Membership on an entity's Board of Directors or advisory committees. Vyas: Gilead: Honoraria; Jazz: Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Takeda: Honoraria; Astellas: Consultancy, Honoraria; Pfizer: Honoraria; Daiichi Sankyo: Honoraria; Janssen: Honoraria; AbbVie: Consultancy, Honoraria. Stein: Janssen Pharmaceuticals: Consultancy; Abbvie: Consultancy; Gilead Sciences, Inc.: Consultancy; Blueprint Medicines: Consultancy; Foghorn Therapeutics: Consultancy; Jazz Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Celgene: Consultancy; PinotBio: Consultancy; Daiichi Sankyo: Consultancy; Syros Pharmaceuticals, Inc.: Consultancy; Genentech: Consultancy; Syndax Pharmaceuticals: Consultancy; Agios Pharmaceuticals, Inc: Consultancy; Astellas: Consultancy; Novartis: Consultancy. Wei: Novartis, Abbvie, Celgene/BMS: Speakers Bureau; Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Membership on an entity's Board of Directors or advisory committees; Former employee of Walter and Eliza Hall Institute: Patents & Royalties: Prof. Andrew Wei is a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax; Abbvie, Amgen, AstraZeneca, Celgene/BMS, Novartis, Servier and F. Hoffmann-La Roche: Research Funding; Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Honoraria; Servier: Consultancy. de Botton: Celgene: Consultancy; Agios: Consultancy, Honoraria; Forma: Consultancy, Honoraria; Astellas: Consultancy; Abbvie: Consultancy; Daiichi: Consultancy; Novartis: Consultancy; Jazz: Consultancy; Pfizer: Consultancy. Chen: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Lord-Bessen: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Martin-Regueira: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Lersch: Celgene, a Bristol-Myers Squibb Company: Current Employment. Gong: Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Guo: Bristol Myers Squibb: Consultancy; Daiichi Sankyo: Consultancy; UCB: Consultancy; Janssen: Consultancy; Gilead: Consultancy; EMD Serono: Consultancy; Evidera: Current Employment. Shi: Bristol Myers Squibb: Consultancy. Montesinos: Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Stemline/Menarini: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Glycomimetics: Consultancy; Tolero Pharmaceutical: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau.

Background: Magrolimab (Hu5F9-G4) is an antibody blocking CD47, a macrophage immune checkpoint and "don't eat me" signal on cancer cells, that eliminates leukemia stem cells by inducing tumor phagocytosis. Hypomethylating agents synergize with magrolimab by inducing "eat me" signals on leukemic blasts, thereby enhancing phagocytosis. Magrolimab with azacitidine (AZA) has shown encouraging activity in frontline acute myeloid leukemia (AML) unfit for intensive chemotherapy and myelodysplastic syndrome. In TP53-mutant (TP53m) AML, it demonstrated an objective response rate of 69%, complete response (CR) rate of 45%, and median overall survival (OS) of 12.9 months. The TP53 gene mutation is observed in approximately 10-15% of newly diagnosed AML and is associated with poor survival. The published first-line median OS in TP53m AML is 5-7 months, regardless of whether patients are treated with intensive chemotherapy or non-intensive approaches, such as a hypomethylating agent with venetoclax (VEN). AML patients harboring the TP53 gene mutation represent a significant unmet medical need. Aims: To evaluate the efficacy, safety, and tolerability of magrolimab+AZA vs physician's choice of VEN+AZA or "7+3" chemotherapy in patients with previously untreated TP53m AML. Design and Methods: This is a phase 3, randomized, open-label, multicenter study. Approximately 346 patients will be randomized (1:1) to magrolimab+AZA (investigational arm) or physician's choice of VEN+AZA or 7+3 chemotherapy, based on patient fitness (NCT04778397). Randomization will be stratified by appropriateness for non-intensive vs intensive therapy, geographic region (US vs non-US sites), and age ( Status: Patients will be enrolled at approximately 140 centers globally. Accrual is ongoing. Disclosures Daver: Gilead Sciences, Inc.: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Glycomimetics: Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Novimmune: Research Funding; Genentech: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Hanmi: Research Funding; Trovagene: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Trillium: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Vyas: Novartis: Honoraria; AbbVie: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Gilead: Honoraria; Jazz: Honoraria; Janssen: Honoraria; Pfizer: Honoraria; Daiichi Sankyo: Honoraria; Takeda: Honoraria. Chao: Gilead Sciences, Inc.: Current Employment; TigaTx: Membership on an entity's Board of Directors or advisory committees; Stanford University: Patents & Royalties; Hepatx Inc: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Iconovir Bio: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; Stanford University Medical School: Membership on an entity's Board of Directors or advisory committees; Foresite capital: Consultancy; Bioverge: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Chimera Bioengineering: Current equity holder in publicly-traded company. Xing: Gilead Sciences, Inc.: Current Employment. Renard: Gilead Sciences, Inc.: Current Employment, Current holder of individual stocks in a privately-held company; Alphabet: Current Employment, Current equity holder in publicly-traded company. Ramsingh: Gilead Sciences, Inc.: Current Employment, Current holder of individual stocks in a privately-held company. Sallman: Syndax: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Magenta: Consultancy; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Membership on an entity's Board of Directors or advisory committees; Intellia: Membership on an entity's Board of Directors or advisory committees. Wei: Prof. Andrew Wei is a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax: Patents & Royalties; MacroGenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche AG: Research Funding; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Magrolimab is an investigational therapy

Background: Magrolimab (Hu5F9-G4) is an antibody blocking CD47, a macrophage immune checkpoint and "don't eat me" signal on cancer cells. Magrolimab induces tumor phagocytosis and eliminates leukemia stem cells. Chemotherapy and hypomethylating agents synergize with magrolimab by inducing "eat me" signals on leukemic blasts, thereby enhancing phagocytosis. Magrolimab+azacitidine (AZA) has shown encouraging clinical efficacy with an objective response rate (ORR) of 63% and a complete remission (CR) or CR with incomplete hematologic recovery (CRi) rate of 54% in first-line acute myeloid leukemia (AML). Newly diagnosed AML patients (pts) who are ineligible for intensive chemotherapy (IC) are incurable despite the progress made with AZA+venetoclax (VEN; median overall survival [OS] 14-18 months), while AML pts with relapsed/refractory (R/R) disease after intensive regimens have a dismal prognosis. Furthermore, for pts in remission, maintenance therapy with oral AZA has improved OS and prevented relapse, although relapse rates remain high. Magrolimab combinations are being evaluated in each of these settings to improve the standard of care. Aims: To evaluate the safety, efficacy, and tolerability of magrolimab combined with antileukemia therapies in first-line pts ineligible for IC (cohort 1), R/R pts after IC (cohort 2), and pts in CR/CRi with presence of minimal residual disease (MRD) after IC (cohort 3). Design and Methods: This is an open-label, multiarm, multicenter study that includes 3 safety run-ins with corresponding phase 2 cohorts (NCT04778410). Pts in cohort 1 must be ≥75 years or 18-74 years with comorbidities that preclude IC. Pts in cohort 2 must have R/R AML after initial IC. Pts in cohort 3 must be ≥55 years and have achieved a CR/CRi with MRD positivity, as assessed by flow cytometry, after IC, and not be candidates for hematopoietic stem cell transplant. Each cohort will initially enroll 6 pts for 1 cycle (28 days) to assess dose-limiting toxicities and determine the recommended phase 2 dose (RP2D). Pts in cohort 1 will receive a combination of magrolimab, VEN, and AZA. Pts in cohort 2 will receive magrolimab in combination with mitoxantrone, etoposide, and cytarabine (MEC). Pts in cohort 3 will receive magrolimab with oral CC-486. All will receive magrolimab on the same schedule. In cycle 1, magrolimab will be administered intravenously (IV) as priming and ramp-up doses at 1 mg/kg on Days 1 and 4, 15 mg/kg on Day 8, and 30 mg/kg on Days 11, 15, and 22. In cycle 2, magrolimab 30 mg/kg will be administered weekly. From cycle 3 onward, magrolimab 60 mg/kg will be administered on Day 1. For cohort 1, AZA (75 mg/m 2) will be administered IV/subcutaneously on Days 1-7 or 1-5, 8, and 9 of each cycle. VEN, MEC, and CC-486 will be administered according to labeled indications. After completion of the safety run-in, additional pts will be enrolled in cohort 1 (n=40), cohort 2 (n=30), and cohort 3 (n=40) for phase 2. In phase 2, pts in cohorts 1 and 3 will receive study treatment at RP2D until disease progression, unacceptable toxicity, or loss of clinical benefit. Pts in cohort 2 will receive magrolimab with MEC for up to 3 cycles followed by magrolimab alone for a total of 12 magrolimab cycles; pts who do not achieve an objective response will discontinue after 2 cycles. In cohorts 1 and 2, the primary efficacy endpoint is the CR/CRi rate. Secondary endpoints of interest include OS, ORR, and MRD-negative CR/CRi rates. The primary efficacy endpoint in cohort 3 is the MRD-negative CR/CRi rate. Status: Accrual is ongoing. Disclosures Vyas: Novartis: Honoraria; AbbVie: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Pfizer: Honoraria; Janssen: Honoraria; Takeda: Honoraria; Daiichi Sankyo: Honoraria; Jazz: Honoraria; Gilead: Honoraria; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding. Daver: Abbvie: Consultancy, Research Funding; Glycomimetics: Research Funding; Trillium: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Hanmi: Research Funding; Novimmune: Research Funding; Genentech: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Pfizer: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Chao: Gilead Sciences, Inc.: Current Employment; TigaTx: Membership on an entity's Board of Directors or advisory committees; Stanford University: Patents & Royalties; Hepatx Inc: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Iconovir Bio: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Chimera Bioengineering: Current equity holder in publicly-traded company; Leukemia and Lymphoma Society: Membership on an entity's Board of Directors or advisory committees; Bioverge: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Stanford University Medical School: Membership on an entity's Board of Directors or advisory committees; Foresite capital: Consultancy. Xing: Gilead Sciences, Inc.: Current Employment. Renard: Alphabet: Current Employment, Current equity holder in publicly-traded company; Gilead Sciences, Inc.: Current Employment, Current holder of individual stocks in a privately-held company. Ramsingh: Gilead Sciences, Inc.: Current Employment, Current holder of individual stocks in a privately-held company. Wei: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffmann-La Roche AG: Research Funding; MacroGenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Prof. Andrew Wei is a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax: Patents & Royalties; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Sallman: Takeda: Consultancy; Magenta: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Intellia: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Speakers Bureau. OffLabel Disclosure: Magrolimab is an investigational therapy

Enasidenib; Conventional care Enasidenib; Atenció convencional Enasidenib; Atención convencional This open-label, randomized, phase 3 trial (NCT02577406) compared enasidenib, an oral IDH2 (isocitrate dehydrogenase 2) inhibitor, with conventional care regimens (CCRs) in patients aged ≥60 years with late-stage, mutant-IDH2 acute myeloid leukemia (AML) relapsed/refractory (R/R) to 2 or 3 prior AML-directed therapies. Patients were first preselected to a CCR (azacitidine, intermediate-dose cytarabine, low-dose cytarabine, or supportive care) and then randomized (1:1) to enasidenib 100 mg per day or CCR. The primary endpoint was overall survival (OS). Secondary endpoints included event-free survival (EFS), time to treatment failure (TTF), overall response rate (ORR), hematologic improvement (HI), and transfusion independence (TI). Overall, 319 patients were randomized to enasidenib (n = 158) or CCR (n = 161). The median age was 71 years, median (range) enasidenib exposure was 142 days (3 to 1270), and CCR was 36 days (1 to 1166). One enasidenib (0.6%) and 20 CCR (12%) patients received no randomized treatment, and 30% and 43%, respectively, received subsequent AML-directed therapies during follow-up. The median OS with enasidenib vs CCR was 6.5 vs 6.2 months (HR [hazard ratio], 0.86; P = .23); 1-year survival was 37.5% vs 26.1%. Enasidenib meaningfully improved EFS (median, 4.9 vs 2.6 months with CCR; HR, 0.68; P = .008), TTF (median, 4.9 vs 1.9 months; HR, 0.53; P < .001), ORR (40.5% vs 9.9%; P

Randomized trials in acute myeloid leukemia (AML) have demonstrated improved survival by the BCL-2 inhibitor venetoclax combined with azacitidine in older patients, and clinical trials are actively exploring the role of venetoclax in combination with intensive chemotherapy in fitter patients with AML. As most patients still develop recurrent disease, improved understanding of relapse mechanisms is needed. We find that 17% of patients relapsing after venetoclax-based therapy for AML have acquired inactivating missense or frameshift/nonsense mutations in the apoptosis effector gene BAX. In contrast, such variants were rare after genotoxic chemotherapy. BAX variants arose within either leukemic or preleukemic compartments, with multiple mutations observed in some patients. In vitro, AML cells with mutated BAX were competitively selected during prolonged exposure to BCL-2 antagonists. In model systems, AML cells rendered deficient for BAX, but not its close relative BAK, displayed resistance to BCL-2 targeting, whereas sensitivity to conventional chemotherapy was variable. Acquired mutations in BAX during venetoclax-based therapy represent a novel mechanism of resistance to BH3-mimetics and a potential barrier to the long-term efficacy of drugs targeting BCL-2 in AML.

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

Selective targeting of BCL-2 with the BH3-mimetic venetoclax has been a transformative treatment for patients with various leukemias. TP-53 controls apoptosis upstream of where BCL-2 and its prosurvival relatives, such as MCL-1, act. Therefore, targeting these prosurvival proteins could trigger apoptosis across diverse blood cancers, irrespective of TP53 mutation status. Indeed, targeting BCL-2 has produced clinically relevant responses in blood cancers with aberrant TP-53. However, in our study, TP53-mutated or -deficient myeloid and lymphoid leukemias outcompeted isogenic controls with intact TP-53, unless sufficient concentrations of BH3-mimetics targeting BCL-2 or MCL-1 were applied. Strikingly, tumor cells with TP-53 dysfunction escaped and thrived over time if inhibition of BCL-2 or MCL-1 was sublethal, in part because of an increased threshold for BAX/BAK activation in these cells. Our study revealed the key role of TP-53 in shaping long-term responses to BH3-mimetic drugs and reconciled the disparate pattern of initial clinical response to venetoclax, followed by subsequent treatment failure among patients with TP53-mutant chronic lymphocytic leukemia or acute myeloid leukemia. In contrast to BH3-mimetics targeting just BCL-2 or MCL-1 at doses that are individually sublethal, a combined BH3-mimetic approach targeting both prosurvival proteins enhanced lethality and durably suppressed the leukemia burden, regardless of TP53 mutation status. Our findings highlight the importance of using sufficiently lethal treatment strategies to maximize outcomes of patients with TP53-mutant disease. In addition, our findings caution against use of sublethal BH3-mimetic drug regimens that may enhance the risk of disease progression driven by emergent TP53-mutant clones.

The 2010 and 2017 editions of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults are widely recognized among physicians and investigators. There have been major advances in our understanding of AML, including new knowledge about the molecular pathogenesis of AML, leading to an update of the disease classification, technological progress in genomic diagnostics and assessment of measurable residual disease, and the successful development of new therapeutic agents, such as FLT3, IDH1, IDH2, and BCL2 inhibitors. These advances have prompted this update that includes a revised ELN genetic risk classification, revised response criteria, and treatment recommendations.

Measurable residual disease (MRD) in patients with acute myeloid leukemia (AML) in remission after intensive chemotherapy is predictive of early relapse and poor survival. Postremission maintenance therapy that prolongs MRD negativity or converts MRD+ patients to MRD− status may delay or prevent relapse and improve overall survival (OS). In the phase 3 QUAZAR AML-001 trial, oral azacitidine (oral-AZA; formerly CC-486), a hypomethylating agent, significantly prolonged OS and relapse-free survival (RFS) compared with placebo in patients aged ≥55 years with AML in first remission after intensive chemotherapy who were not candidates for hematopoietic stem cell transplantation. In this trial, MRD (≥0.1% leukemic cells in bone marrow) was assessed by multiparameter flow cytometry in serial samples collected at baseline and on day 1 of every 3 cycles. As expected, baseline MRD status was significantly associated with both OS and RFS. Multivariate analyses showed oral-AZA significantly improved OS and RFS vs placebo independent of baseline MRD status. Oral-AZA treatment also extended the duration of MRD negativity by 6 months vs placebo and resulted in a higher rate of conversion from MRD+ at baseline to MRD− during treatment: 37% vs 19%, respectively. In the oral-AZA arm, 24% of MRD responders achieved MRD negativity >6 months after treatment initiation. Although presence or absence of MRD was a strong prognostic indicator of OS and RFS, there were added survival benefits with oral-AZA maintenance therapy compared with placebo, independent of patients’ MRD status at baseline. Registered at clinicaltrials.gov as #NCT01757535.

Germline variants in RUNX1, GATA2 and DDX41 may confer a predisposition to hereditary haematopoietic malignancies (HHMs) such as MDS and AML yet have distinct age ranges of malignancy diagnosis and a highly variable overall risk for leukemogenesis. The increased awareness and identification of carriers of these germline variants, particularly before development of malignancy, has changed the way in which individuals and families need to be managed in the clinic. Individuals need lifelong monitoring and may also need modification to treatments when malignancy does develop, compared to sporadic counterparts. Gaps in understanding pre-malignant states in HHM syndromes have hampered efforts to design effective clinical surveillance regimes, provide personalized pre-emptive treatments, and appropriate counselling to patients.

The BCL-2 inhibitor venetoclax combined with hypomethylating agents or low-dose cytarabine represents an important new therapy for older or unfit patients with acute myeloid leukemia (AML). We analyzed 81 patients receiving these venetoclax-based combinations to identify molecular correlates of durable remission, response followed by relapse (adaptive resistance), or refractory disease (primary resistance). High response rates and durable remissions were typically associated with NPM1 or IDH2 mutations, with prolonged molecular remissions prevalent for NPM1 mutations. Primary and adaptive resistance to venetoclax-based combinations was most commonly characterized by acquisition or enrichment of clones activating signaling pathways such as FLT3 or RAS or biallelically perturbing TP53. Single-cell studies highlighted the polyclonal nature of intratumoral resistance mechanisms in some cases. Among cases that were primary refractory, we identified heterogeneous and sometimes divergent interval changes in leukemic clones within a single cycle of therapy, highlighting the dynamic and rapid occurrence of therapeutic selection in AML. In functional studies, FLT3 internal tandem duplication gain or TP53 loss conferred cross-resistance to both venetoclax and cytotoxic-based therapies. Collectively, we highlight molecular determinants of outcome with clinical relevance to patients with AML receiving venetoclax-based combination therapies.

Introduction Midostaurin is the only approved FLT3 inhibitor for combination with intensive induction and consolidation chemotherapy in newly diagnosed patients with FLT3 mutant AML. The FLT3 inhibitor, sorafenib, was investigated in the randomized SORAML trial (Röllig, Lancet Onc 2015), in combination with intensive chemotherapy (IC) for newly diagnosed adults with AML Methods The Australasian Leukaemia and Lymphoma Group (ALLG) conducted a randomized phase 2 study [ACTRN12611001112954] in 99 adults aged 18-65 years with newly diagnosed FLT3-ITD positive (allelic ratio (AR) ≥0.05) AML to determine whether addition of SOR to IC would improve event-free survival (EFS). The study was powered to identify a 25% increase in 2-year EFS with SOR. Patients 18-55 yrs received induction with IDAC-3 (idarubicin [IDA] 12 mg/m2 D1-3 and ara-C 1.5 g/m2 BD D1,3,5,7); patients 56-65 received 7+3 (IDA 12 mg/m2 D1-3 and ara-C 100 mg/m2 D1-7 IVI). Patients were randomized 2:1 to SOR or PBO 400 mg BD on days 4-10 of induction and each consolidation cycle. Due to the pharmacokinetic interaction between SOR and azoles, antifungal prophylaxis during induction was with AmBisome 5 mg/kg IV twice weekly. For consolidation, patients 18-55 yrs received 2 cycles of IcE (IDA 9 mg/m2 D1-2, ara-C 100 mg/m2 D1-5 IVI and etoposide 75 mg/m2 D1-5), those 56-65 yrs received 2 cycles of IDAC-2 (IDA 12 mg/m2 D1-2 and ara-C 1g/m2 BD D1,3,5). Maintenance was with SOR/PBO 400 mg bd days 1-28 for 12 cycles. Allogeneic HCT (allo-HCT) was at investigator discretion. SOR/PBO was not continued post allo-HCT. The primary endpoint was EFS without censoring for allo-HCT with events defined as failure to achieve complete remission (CR) or CR with incomplete hematologic recovery (CRi), relapse or death. Pre-specified secondary endpoints included overall response rate (ORR) defined as CR and CRi, tolerability, EFS according to FLT3-ITD AR < or ≥ 0.7 and impact of randomization on allograft outcome. Results Between Jan 2013-May 2018, 18 centers randomized 99 patients to induction with either SOR (n=65) or PBO (n=33); one patient later found to be FLT3-ITD negative was excluded. Patient characteristics are shown in Table 1. Treatment arms were balanced apart from fewer patients in the SOR arm with NPM1 mutant AML. Deliverability of therapy was comparable, with commencement of consolidation in 78% and 79% and maintenance therapy in 32% and 27% in the SOR and PBO arms, respectively. The overall response rate (ORR) was high in both arms; 91% in the SOR (CR 80%, CRi 11%) and 94% in the PBO (CR 70%, CRi 24%) arm. In the SOR arm, 5% achieved partial remission, went off study and were deemed treatment failures. With a median overall follow-up of 25 mo, there was no significant difference in EFS (HR 0.87 95% CI 0.50-1.49; P=0.61)(Fig A) or OS (HR 0.70 95% CI 0.38-1.29; P=0.26)(Fig. B), nor in a sensitivity analysis with censoring at HCT. 2 yr EFS was 47.9% (SOR) vs 45.4% (PBO) and 2-year OS 66.8% (SOR) vs 56.4% (PBO). Hematopoietic cell transplant (HCT) in CR1 was performed in 62% and 58% in the SOR and PBO arms, respectively. For patients in CR1, 2 yr OS post-HCT was 78.5% (SOR) vs 54.2% (PBO)(Fig C). Suggestive of an on-target effect against FLT3-ITD, the impact of SOR on OS appeared greater for patients with higher FLT3-ITD AR ≥0.7 (Fig. D) (Table 2). Only one early death (within 30 days) was recorded in each treatment arm. The frequency of grade 3-4 adverse events (AEs) were similar between the two arms, apart from palmar-plantar rash, reported as drug-related in 15.4% and 6.1% pts in the SOR and PBO arms, respectively. Correlative studies will be reported in a companion abstract. Conclusions SOR did not improve EFS when combined with intensive chemotherapy in adults with newly diagnosed FLT3-ITD AML. Although not powered for significance, SOR showed a trend for improved OS among patients with higher FLT3-ITD AR or receiving HCT in CR1. Further exploration of more potent FLT3 inhibitors in the pre- and post-allograft setting are warranted for patients with newly diagnosed FLT3 mutant AML. Acknowledgements: The ALLG AMLM16 trial was funded through an Australian Government NHMRC grant and a research grant from the Leukaemia Foundation of Australia. Bayer supplied sorafenib and Gilead AmBisome. Disclosures Wei: Roche: Honoraria; Servier: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Amgen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: AW is eligible for royalty payments related to venetoclax; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria; Macrogenics: Honoraria. Enjeti:Novartis: Membership on an entity's Board of Directors or advisory committees; Alexion: Speakers Bureau; Bayer: Speakers Bureau; Sanofi: Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. D'Rozario:Abbvie: Membership on an entity's Board of Directors or advisory committees; BMS/ Celgene: Membership on an entity's Board of Directors or advisory committees. Marlton:Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Verner:Janssen Cilag Pty Ltd.: Research Funding. Hahn:Roche: Honoraria; Astra Zeneca: Honoraria. Hiwase:Novartis Australia: Research Funding. Anstee:Walter and Eliza Hall Institute: Patents & Royalties: milestone and royalty payments related to venetoclax.. Levis:FujiFilm: Honoraria, Research Funding; Amgen: Honoraria; Daiichi-Sankyo: Honoraria; Menarini: Honoraria; Astellas: Honoraria, Research Funding. Bajel:Abbvie: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria. Roberts:Genentech: Patents & Royalties: for venetoclax to one of my employers (Walter & Eliza Hall Institute); I receive a share of these royalties; Janssen: Research Funding; Servier: Research Funding; AbbVie: Research Funding. OffLabel Disclosure: Sorafenib for FLT3-ITD AML

Introduction Molecular MRD assays targeting NPM1 mutant (mut) transcripts have an established role for monitoring treatment efficacy in patients with NPM1mut AML. Approximately 25% of NPM1mut patients show persistent MRD level in the bone marrow (BM) at the end of treatment (EOT), which is associated with a higher risk of relapse (Ivey, NEJM 2016; Kronke, JCO 2011). Molecular persistence at low copy number (MP-LCN) is defined by the European LeukemiaNet (ELN) as MRD positivity in patients in morphological complete remission (CR) with Methods Consecutive patients with newly diagnosed NPM1mut AML receiving at least 2 cycles of intensive chemotherapy were included if MRD remained detectable at EOT. UK patients were all enrolled in the NCRI AML17 and AML19 studies. Australian patients were retrospectively identified. BM samples were analyzed by either RT-qPCR (n=75) (Ivey, NEJM 2016) or ultra-deep next-generation sequencing (UD-NGS, n=5, excluded from Cox model). We applied the ELN definitions for molecular progression or relapse (considered together as molecular failure [MF]), MP-LCN and complete molecular remission (CRMRD-). Kaplan Meier survival estimates were calculated from EOT to death (OS), and/or morphologic relapse (RFS), and/or MF (EFS). The optimal NPM1mut expression threshold was pre-determined by recursive partitioning. Variables with p Results A total of 80 patients had NPM1mut detectable at a median of 37 days (range 19-90; 12 [15%] were >60 days) from last course of chemotherapy; characteristics summarized in Table 1. The majority of patients (89%) had received 3-4 cycles of chemotherapy. At EOT, the median NPM1mut transcript level by RT-qPCR was 11 copies (range 0.3-8699; 3 were >2000) and median reduction from baseline was 4.7 log (range 2.1-6.0). A total of 34 patients (45%; 4 not monitored) fulfilled the criteria for MP-LCN. With a median follow-up time of 24 mo (range 8-77), 27 (34%) spontaneously achieved a sustained CRMRD- for >6 months, 31 (39%) had MF and 13 (16%) had morphologic relapse without preceding MF (due to rapid relapse [n=8], lack of monitoring [n=3], extramedullary or NPM1 wild-type relapse [n=1 each]) (Figure 1). Nine patients (11%) had persisting MP-LCN (included transient MRD negativity): median interval between EOT to the last known positive sample was 12 mo (range 3-32), and all patients currently remain alive and without morphologic relapse by the data cut-off date July 13, 2020. Next, we examined the variables associated with MF and/or morphologic relapse. In univariate analysis, factors associated (p Conclusions We describe the natural history of patients with NPM1 mutated AML who remain MRD positive after completing intensive chemotherapy. Almost half either spontaneously achieve MRD-negativity or have stable low-level expression without relapse with minimum follow up of 8 mo. Patients with both FLT3-ITD and Disclosures Tiong: Pfizer: Consultancy; Servier: Consultancy; Amgen: Consultancy, Honoraria. Dillon:Abbvie: Honoraria, Research Funding; Novartis: Honoraria; Menarini: Honoraria; Astellas: Honoraria; Pfizer: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria, Research Funding. Bajel:Abbvie: Honoraria; Pfizer: Honoraria; Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria; Astellas: Honoraria. Russell:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees; Jazz: Research Funding, Speakers Bureau. Wei:MacroGenics: Consultancy, Honoraria; Pfizer: Honoraria; Servier: Consultancy, Honoraria, Research Funding; Walter and Eliza Hall Institute: Other: former employee and receives a fraction of its royalty stream related to venetoclax; Celgene: Consultancy, Honoraria, Research Funding; AbbVie Inc.: Consultancy, Honoraria, Research Funding; Genentech: Honoraria; Astra Zeneca: Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding.

Background : For patients (pts) with acute myeloid leukemia (AML), preserving and measuring perceptions of health-related quality of life (HRQoL) is important, particularly for those ineligible for intensive chemotherapy and with a poor prognosis, especially when evaluating new treatment regimens. This analysis from 2 Phase 3 trials, Viale-A (NCT02993523) and Viale-C (NCT03069352), evaluated HRQoL, including key symptoms and aspects of functioning, in pts with AML receiving venetoclax (VEN) co-administered with azacitidine (AZA) (Viale-A) or low-dose cytarabine (LDAC) (Viale-C). Methods: Viale-A and Viale-C included treatment-naïve pts with AML, ≥18 years of age, and ineligible to receive intensive chemotherapy. Pts were randomized 2:1 to receive VEN +AZA or placebo (PBO)+AZA in Viale-A, and VEN+ LDAC or PBO+LDAC in Viale-C. Pt-reported outcome (PRO) measures included the PROMIS Cancer Fatigue Short Form 7a, the EORTC QLQ-C30 global health status (GHS)/QoL and physical functioning [PF] subscales, and the EQ-5D-5L health status visual analog scale (VAS). PRO data were collected on Day 1 of every 28-day cycle throughout both trials. Time to deterioration (TTD) was assessed to quantify differences between treatment groups. TTD was defined as worsening from baseline in PRO-specific meaningful change thresholds of ≥10, 7, or 5 points for the EORTC-QLQ-C30, EQ-5D-5L VAS, and PROMIS Fatigue, respectively. TTD differences between treatment arms were analyzed using Kaplan-Meier curves, unadjusted log-rank tests, and Cox PH models adjusted for key covariates (age, baseline ECOG and PRO scores, AML type, and cytogenetic risk category). TTD analyses were conducted for all pts in the full dataset who survived up to a given assessment with available data on ≥1 PRO measures from baseline. Results: Viale-A included 431 pts (VEN+AZA: 286, PBO+AZA: 145), of whom 60% were male; median age was 76 years. Compared with PBO+AZA pts, VEN+AZA pts had a non-statistically significant trend to longer TTD in GHS/QoL (median in months [95% CI]: 16.5 [95% CI: 9.8, NE] vs. 9.3 [95% CI: 4.7, 16.6], P=0.066) and fatigue (9.3 [7.2, 16.6] vs. 8.6 [4.2, 16.6], P=0.189) (Figure 1A, B). VEN+AZA pts had significantly longer TTD in PF (9.7 [6.7, 16.0] vs. 6.2 [4.7, 9.5], P=0.028) and health status VAS (10.7 [7.5, 18.6] vs. 3.9 [2.4, 7.4], P Conclusions: Results showed a longer TTD in PRO measures of global health status, VAS, fatigue, and PF for pts receiving VEN combinations vs AZA or LDAC monotherapy, with significantly longer TTD observed for all PRO measures from the unadjusted and adjusted analyses in Viale-C, and for PF and health VAS in Viale-A. These results suggest that VEN conveys meaningful benefit in terms of HRQoL. Limitations included the small sample size beyond early cycles in these studies; however, the early separation of the TTD curves with the initial larger sample size, suggests that these results are not due to chance variability and are statistically valid. Overall the improvements in PROs with VEN are consistent with previous efficacy reports. In summary, VEN appears to have a positive impact on the HRQoL of pts with AML who are ineligible for intensive chemotherapy, leading to a longer preservation of functioning and overall health status. Disclosures Pratz: Millennium: Research Funding; Daiichi Sankyo: Research Funding; Agios: Other: Scientific Advisory Board, Research Funding; Celgene: Other: Scientific Advisory Board; Boston BioMedical: Consultancy; AbbVie: Other: Scientific Advisory Board, Research Funding; Astellas: Other: Scientific Advisory Board, Research Funding; Jazz Pharmaceutical: Consultancy. Panayiotidis:AbbVie: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Genesis: Honoraria, Research Funding; Takeda: Honoraria; Phizer: Honoraria; ASH: Honoraria; Janssen: Honoraria; Gilead: Honoraria. Jonas:AbbVie: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; Tolero: Consultancy; Treadwell: Consultancy; Forty Seven: Research Funding; Daiichi Sankyo: Research Funding; Genentech/Roche: Research Funding; Amgen: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; GlycoMimetics: Consultancy, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Research Funding; Accelerated Medical Diagnostics: Research Funding; AROG: Research Funding; LP Therapeutics: Research Funding; Forma: Research Funding; Pharmacyclics: Research Funding; Pfizer: Research Funding; Jazz: Consultancy, Research Funding; Sigma Tau: Research Funding; Celgene: Consultancy, Research Funding; F. Hoffmann-La Roche: Research Funding; Incyte: Research Funding; Hanmi: Research Funding; Takeda: Consultancy. Dinardo:Takeda: Honoraria; Celgene: Research Funding; Agios: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Notable Labs: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; Calithera: Research Funding; ImmuneOnc: Honoraria. Novak:Janssen: Other: Travel expenses; Novartis: Consultancy; Roche: Consultancy; Pfizer: Consultancy; Amgen: Consultancy, Other: Travel expenses; Takeda: Consultancy. Pejsa:Oktal Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sandoz: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alvogen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pliva: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Stevens:Amgen, MorphoSys: Consultancy. Yeh:Amgen: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Astex: Membership on an entity's Board of Directors or advisory committees. Kim:AbbVie: Other: Clinical trials investigator. Fracchiolla:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company), Speakers Bureau; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Yamamoto:Takeda: Consultancy, Honoraria, Research Funding; Yakult: Research Funding; Zenyaku: Research Funding; SymBio: Research Funding; Solasia Pharma: Research Funding; Aichi Cancer Center: Current Employment; AbbVie: Consultancy, Honoraria, Research Funding; Astra-Zeneca: Consultancy, Research Funding; Bayer: Research Funding; Bristol-Myers Squibb: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Chugai: Consultancy, Honoraria, Research Funding; Eisai: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy; IQIVA/HUYA: Honoraria; HUYA: Consultancy; IQIVA/Incyte: Research Funding; Gilead Sciences: Research Funding; Janssen: Honoraria; Kyowa Kirin: Honoraria; Meiji Seika Pharma: Consultancy, Honoraria; Mochida: Honoraria; MSD: Consultancy, Honoraria, Research Funding; Mundipharma: Consultancy, Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ono: Consultancy, Honoraria, Research Funding; Otsuka: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria; Sanofi: Honoraria; Sumitomo Dainippon: Honoraria; Stemline Therapeutics: Consultancy. Ofran:AbbVie: Membership on an entity's Board of Directors or advisory committees. Wei:Astra Zeneca: Honoraria, Research Funding; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: AW is eligible for royalty payments related to venetoclax; Novartis: Honoraria, Research Funding, Speakers Bureau; Amgen: Honoraria, Research Funding; Macrogenics: Honoraria; Roche: Honoraria; Servier: Consultancy, Honoraria, Research Funding; Pfizer: Honoraria; Janssen: Honoraria; Abbvie: Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau. Bui:AbbVie: Current Employment, Current equity holder in publicly-traded company. Benjamin:AbbVie: Current Employment, Current equity holder in publicly-traded company. Kamalakar:AbbVie: Current Employment, Other: may hold stock or other options. Potluri:AbbVie: Current Employment, Other: may hold stock or stock options. Mendes:AbbVie: Current Employment, Current equity holder in publicly-traded company. Devine:Genentech: Current Employment, Current equity holder in publicly-traded company. Fiedler:Daiichi Sankyo: Other: support for meeting attendance; Gilead: Other: support for meeting attendance; Jazz Pharmaceuticals: Honoraria, Other: support for meeting attendance; Abbvie: Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; ARIAD/Incyte: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Other: support for meeting attendance, Patents & Royalties, Research Funding.

Introduction The Australasian Leukaemia and Lymphoma Group (ALLG) conducted a randomized trial (AMLM16) combining the FLT3 inhibitor sorafenib (SOR) or placebo (PBO) with intensive induction and consolidation chemotherapy, followed by 12 months of maintenance therapy in patients with FLT3-ITD mutant AML. The clinical results of the AMLM16 study are detailed in a companion abstract co-submitted to ASH 2020. We hypothesized that the optimal time to administer sorafenib would be d4-10 of induction in order to limit overlap with anthracyclines on d1-3 and to avoid high FLT3 ligand (FLT3L) levels beyond d10, which could abrogate FLT3 on-target activity and diminish the therapeutic index. Key objectives of the correlative studies were to correlate in vivo SOR activity on suppression of FLT3 phosphorylation (P-FLT3) using the plasma inhibitory assay (PIA) with relapse risk and to assess for the presence of FLT3-ITD measurable residual disease (MRD) after therapy. Methods Patients aged 18-65 years with newly diagnosed AML (excluding APML) were enrolled to a National Blood Cancer Registry; those with a FLT3-ITD mutant: wild-type allelic ratio (AR) ≥ 0.05 were eligible for enrolment to the AMLM16 study. Patients were randomized 2:1 to SOR or PBO 400mg orally bd on d4-10 of induction and each consolidation cycle in combination with intensive chemotherapy and for 12 months as maintenance monotherapy. Serum FLT3-L levels were measured by ELISA, SOR and its metabolites by mass spectrometry. SOR mediated inhibition of FLT3 was measured in serum samples using the PIA as previously described (Levis, Blood 2006) in which P-FLT3 inhibition to ≤15% baseline is defined as response. Quantitation of FLT3-ITD levels by NGS was performed at study screening and after each induction and consolidation chemotherapy cycle. Quantitation was by amplicon-based sequencing which detected ITDs >6 bp with a sensitivity of 0.001%: levels below and above this were termed measurable residual disease (MRD) negative and positive respectively. Prepared libraries were sequenced (Illumina) using 150 bp paired-end reads with a minimum coverage of 400,000 reads. Bioinformatics analysis was performed using getITD (Blätte, Leukemia, 2019). Results 98 evaluable patients were randomized to induction with either SOR (n=65) or PBO (n=33) with a FLT3-ITD AR ranging from 0.05 to 8.4. FLT3-ITD AR was ≥ 0.5 or ≥ 0.7 in 48% and 29%, respectively. During induction, FLT3-L levels increased by an average of 150-fold from d4 to d10 and a further 1.6-fold to d15, with a return to baseline by d28. Serial plasma samples to assess PIA were available for 63 patients (Fig A). Response to ≤15% on d10 (relative to d4) was observed in 88% of SOR patients, compared with 4.5% receiving PBO. The relapse risk was 32% and 62% among PIA responders and non-responders, respectively (Fig A). Among patients with PIA response to ≤15% by d10 (the last day of SOR/PBO), only 8.3% had evidence of a sustained PIA response by d15. Reduction of FLT3-ITD to undetectable levels (VAF We compared the relationship between inhibition of P-FLT3 on d10 and bone marrow FLT3-ITD MRD after induction with relapse risk (Fig D, E). In the SOR arm, if P-FLT3 was not reduced to ≤15%, all patients had persistent FLT3-ITD MRD after induction and the relapse risk was 80% (Fig D). In contrast, if P-FLT3 inhibition was ≤15% and FLT3-ITD MRD not detected, the relapse risk was only 20%. In the PBO arm after induction, persistent and undetectable FLT3-ITD MRD (VAF Conclusions These studies demonstrate that in vivo SOR inhibited P-FLT3 to ≤15% during induction in the majority of cases and was associated with reduced relapse risk. Persistent FLT3-ITD MRD post-induction was associated with a high relapse risk in both treatment arms. For patients receiving SOR, failure to reduce P-FLT3 response to ≤15% was associated with a high risk of persistent FLT3-ITD MRD and clinical relapse. Disclosures Anstee: Walter and Eliza Hall Institute: Patents & Royalties: milestone and royalty payments related to venetoclax.. Levis:Menarini: Honoraria; Amgen: Honoraria; FujiFilm: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria; Astellas: Honoraria, Research Funding. Enjeti:Novartis: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Alexion: Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees; Bayer: Speakers Bureau; Sanofi: Speakers Bureau. D'Rozario:Abbvie: Membership on an entity's Board of Directors or advisory committees; BMS/ Celgene: Membership on an entity's Board of Directors or advisory committees. Marlton:AbbVie: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Roberts:Janssen: Research Funding; Servier: Research Funding; AbbVie: Research Funding; Genentech: Patents & Royalties: for venetoclax to one of my employers (Walter & Eliza Hall Institute); I receive a share of these royalties. Wei:Astra Zeneca: Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria, Research Funding, Speakers Bureau; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: AW is eligible for royalty payments related to venetoclax; Roche: Honoraria; Macrogenics: Honoraria; Servier: Consultancy, Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Pfizer: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria. OffLabel Disclosure: Sorafenib for FLT3-ITD AML

Background: Hypomethylating agents (HMA) form the current standard treatment for patients with higher-risk myelodysplastic syndrome (HR-MDS) who are not eligible for allogeneic hematopoietic stem cell transplantation (HSCT). However, overall response rates (ORRs) remain low in patients receiving azacitidine (Aza), and median overall survival (OS) is reported as ~15 months (Sekeres et al. J Clin Oncol. 2017). In addition, there are few data on patient-reported outcomes (PROs) published in this population while on treatment. Venetoclax (Ven) is a selective, potent, orally bioavailable BCL-2 inhibitor, which has demonstrated synergy with HMA in preclinical studies of HR-MDS. From an ongoing, open-label, dose-escalation, Phase 1b study (NCT02942290) evaluating Ven+Aza for the treatment of treatment-naïve HR-MDS, we report the updated safety and efficacy in all treated patients and the exploratory analysis of key PROs in patients who received the recommended Phase 2 dose (RP2D). Methods: Patients aged ≥18 years with treatment-naïve HR-MDS, International Prognostic Scoring System intermediate-2 or high, bone marrow blasts Results: At data cutoff, December 31, 2019, 57 patients had received Ven+Aza, with a median follow-up of 13.0 months (95% confidence interval [CI] 11.3, 15.6 months). The majority of patients were male (75%); median age was 71 years (range 26-85 years); and 89% had ECOG score 0-1. All patients experienced ≥1 adverse event (AE), the most common being constipation (54%), neutropenia (51%), and nausea (51%). Grade ≥3 AEs were experienced by 97% of patients, with neutropenia (51%), febrile neutropenia (46%), and thrombocytopenia (30%) the most common. Febrile neutropenia was the most common serious AE (42%). The 30-day mortality rate was 2%. The ORR was 77%, including complete remission (CR) and marrow CR (mCR) achieved by 42% and 35% of patients (of whom 40% achieved mCR + hematological improvement), respectively; none achieved partial remission. Median OS was not reached (95% CI 16.2 months, not estimable; Figure 1). Median duration of response was 14.8 months (95% CI 12.9 months, not estimable). Median progression-free survival was 17.5 months (14.5, not estimable). Of the patients who received the RP2D of Ven 400 mg for 14 days/28-day cycle in combination with Aza, physical functioning, as measured by the EORTC QLQ-C30, was maintained through 48 weeks of treatment. In addition, clinically meaningful improvement in fatigue and dyspnea, as measured by the EORTC QLQ-C30, was achieved by the beginning of Cycle 5 and was maintained through Week 48 (Cycle 13; Figure 2). Conclusions: The combination of Ven+Aza demonstrates promising efficacy, including response durability, and an acceptable safety profile for patients with HR-MDS. Maintenance in physical functioning and clinically meaningful improvement in dyspnea and fatigue were observed throughout the first 48 weeks, although these data are not yet mature and low patient numbers beyond Cycle 7 limit conclusions. Additional follow-up data and correlation with disease risk features including mutations will be presented at the meeting. Disclosures Garcia: Pfizer: Research Funding; Eli Lily: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Wei:Amgen: Consultancy, Honoraria, Research Funding; MacroGenics: Consultancy, Honoraria; Servier: Consultancy, Honoraria, Research Funding; Walter and Eliza Hall Institute: Other: former employee and receives a fraction of its royalty stream related to venetoclax; Pfizer: Honoraria; Genentech: Honoraria; Astra Zeneca: Honoraria, Research Funding; AbbVie Inc.: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding. Borate:Genentech: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Research Funding; AbbVie: Other: Investigator in AbbVie-funded clinical trials; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding. Fong:Astellas: Honoraria; Pfizer: Honoraria; Novartis: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; AbbVie: Honoraria. Baer:Forma: Other: Institutional research funding; Astellas: Other: Institutional research funding; AbbVie: Other: Institutional research funding; Incyte: Other: Institutional research funding; Kite: Other: Institutional research funding; Oscotec: Other: Institutional research funding; Takeda: Other: Institutional research funding. Nolte:AbbVie: Other: Investigator on an AbbVie funded clinical trial. Jurcic:AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Research Funding; Daiichi-Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Arog Pharmaceuticals: Research Funding; Astellas: Research Funding; Forma Therapeutics: Research Funding; Genentech: Research Funding; Kura Oncology: Research Funding; PTC Therapeutics: Research Funding; Syros Pharmaceuticals: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Jacoby:Takeda: Consultancy; AbbVie: Research Funding; Jazz Pharmaceuticals: Research Funding. Hong:F. Hoffmann-La Roche: Current equity holder in publicly-traded company; Genentech, Inc.: Current Employment. Platzbecker:Geron: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Amgen: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Odenike:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astex Pharmaceuticals, NS Pharma, Gilead Sciences, Janssen Oncology, Oncotherapy, Agios, CTI/Baxalta, Aprea: Other: Institutional research funding; Astra Zeneca: Research Funding; Incyte: Other: Institutional research funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Impact Biomedicines: 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. Cunningham:AbbVie: Research Funding; Amgen: Research Funding; Astex: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Novartis: Research Funding; Principia Biopharma: Research Funding; Rigel Ilona: Research Funding. Zhou:AbbVie: Current Employment, Other: may hold stock or other options. Tong:AbbVie, Inc.: Current Employment, Other: may hold stock or other options. Hogdal:AbbVie: Current Employment, Other: may hold stock or other options. Kamalakar:AbbVie: Current Employment, Other: may hold stock or other options. Hutti:AbbVie Inc.: Current Employment, Other: may hold stock or stock options. Kye:AbbVie: Current Employment, Other: may hold stock or other options. Garcia-Manero:Novartis: Research Funding; Merck: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Amphivena Therapeutics: Research Funding; AbbVie: Honoraria, Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; H3 Biomedicine: Research Funding; Jazz Pharmaceuticals: Consultancy; Acceleron Pharmaceuticals: Consultancy, Honoraria; Onconova: Research Funding. OffLabel Disclosure: Venetoclax is a BCL-2 inhibitor approved for use in CLL and in combination with azacitidine, decitabine, or low-dose cytarabine for the treatment of newly-diagnosed AML who are 75 years or older or who have comorbidities that preclude use of intensive induction chemotherapy; the current clinical trial reports use in MDS

Introduction The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in ~20% of patients (pts) with AML ≥70 years (Schneider et al, 2012). Both FLT3-ITD and FLT3-TKD mutations (mut) are associated with AML proliferation and potentially targetable with small molecule inhibitors. The presence of a FLT3mut, particularly FLT3-ITD, often correlates with high leukemic burden and risk of relapse despite high response rates (Gale et. al, 2008). There is limited evidence of the effect of currently available therapies on treatment-naïve AML pts unfit for intensive treatment with FLT3mut. We evaluated the efficacy and safety of venetoclax (Ven) and Azacitidine (Aza) combination among treatment-naïve AML pts with co-morbidities and/or age ≥ 75 years, unfit for intensive treatment, and with FLT3mut. Methods Data were pooled from pts enrolled in a phase 3 study (NCT02993523, data cut-off: 04Jan2020) that compared pts treated with Ven+Aza or placebo (Pbo)+Aza, and a prior phase 1b study (NCT02203773, data cut-off: 19Jun2019) where pts were treated with Ven+Aza. Pts on Ven+Aza received Ven 400 mg daily orally (days 1-28) and Aza (75 mg/m2; days 1-7/28-day cycle). Disease assessments were performed per the modified International Working Group response criteria for AML. DNA was isolated from bone marrow aspirates collected from pts prior to the first dose of study drug and analyzed centrally. Pts with positive test results for FLT3; [Leukostrate FLT3 CDx for phase 3 study or MyAML panel (Invivoscribe) for Phase 1b study] were counted as mutation "detected"; pts with a negative test result were counted as mutation "not detected." Pts without a result either due to an inconclusive test or missing specimen were not included in the analyses. Results In this pooled analysis, FLT3mut was detected in 40 pts treated with Ven+Aza and 22 pts treated with Pbo+Aza. At baseline (Ven+Aza/Pbo+Aza), the median age was 75 (range: 49-91)/75 (65-85) years. Cytogenetic risks were: intermediate: 88%/96% and poor: 13%/5%, Eastern Co-operative Oncology Group performance scores were: 0-1: 40%/50% and 2-3: 60%/50%. 78%/86% had de novo AML, while 23%/14% had secondary AML. FLT3-ITD was detected in 28/13 and FLT3-TKD in 13/10 pts, respectively. FLT3-ITD allelic ratios were: Complete response (CR)+CR with partial hematologic recovery (CRh) rates in FLT3mut pts (Ven+Aza/Pbo+Aza) were 65% (95% CI:48%-79%)/18% (5%-40%) (Table) with a median duration of response (mDoR) 18.3 [95% CI: 10.1- not reached (NR)]/15.1 (13.9-NR) mos. Median time to first CR/CRh response was 1.0/3.2 months (mos). 43%/0% achieved CR+CRh by initiation of cycle (C) 2. Median overall survival (mOS) was 13.3 (95% CI: 8.4-23.5)/8.6 (5.9-14.7) mos, respectively. Among pts with FLT3-ITD, CR+CRh rates (Ven+Aza/Pbo+Aza) were 61% (95% CI: 41%-79%)/23% (5%-54%) with mDoR 17.4 (95% CI: 3.7-NR)/14.5 (13.9-15.1) mos. The median time to first CR/CRh response was 1.0/3.5 mos and 39%/0% pts achieved CR+CRh by initiation of C2. The mOS was 11.5 (95% CI: 6.4-23.5)/8.5 (6.1-20.3) mos, respectively. CR+CRh rates in pts with FLT3-TKD were 69% (95% CI: 39%-91%)/20% (3%-56%) with mDoR 18.3 (95% CI: 3.0-NR)/NR (15.1-NR) mos. The median time to first CR/CRh response was 1.0/2.7 mos and 46%/0% achieved a response by initiation of C2. The mOS was 19.2 (95% CI:1.8-NR/10.0 (0.2-14.7) mos, respectively. In pts treated with Ven+Aza, CR+CRh rates among pts with FLT3 detected/FLT3 not detected were 65% (95% CI: 48%-79%)/63% (56%-69%) with mDoR 18.3 (95% CI: 10.1-NE)/18.1 (15.3-NR) mos. The mOS was 13.3 (95%CI: 8.4-23.5)/14.1 (10.6-18.7) mos, respectively (Figure). Among pts treated with Ven+Aza, grade 3/4 hematologic adverse events (AEs) in pts with FLT3 detected/FLT3 not detected was 67%/77%, and included anemia (33%/25%), neutropenia (36%/33%), thrombocytopenia (39%/36%), and febrile neutropenia (36%/43%). Grade 3/4 hematologic AEs among pts with FLT3-ITD/FLT3-TKD treated with Ven+Aza was 67%/69%. Conclusion Ven+Aza compared to Aza monotherapy resulted in significantly higher CR+CRh rates among treatment-naïve pts with FLT3mut ineligible for intensive chemotherapy. In this unselected AML population, insufficient pt numbers in various subgroups limit the ability to draw conclusions regarding DoR and mOS for FLT3-ITD and TKD subgroups. There were no unexpected toxicities in the Ven+Aza arm. Future studies with larger sample sizes are warranted. Disclosures Konopleva: Ascentage: Research Funding; Amgen: Consultancy; Genentech: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Research Funding; Forty-Seven: Consultancy, Research Funding; Rafael Pharmaceutical: Research Funding; Kisoji: Consultancy; Agios: Research Funding; Calithera: Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; AstraZeneca: Research Funding; AbbVie: Consultancy, Research Funding; Sanofi: Research Funding; Eli Lilly: Research Funding; Cellectis: Research Funding; Ablynx: Research Funding. Thirman:AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Syndax: Research Funding; TG Therapeutics: Research Funding; Tolero: Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Gilead Sciences: Research Funding. Pratz:Millennium: Research Funding; Celgene: Other: Scientific Advisory Board; AbbVie: Other: Scientific Advisory Board, Research Funding; Astellas: Other: Scientific Advisory Board, Research Funding; Boston BioMedical: Consultancy; Agios: Other: Scientific Advisory Board, Research Funding; Daiichi Sankyo: Research Funding; Jazz Pharmaceutical: Consultancy. Letai:Flash Therapeutics: Membership on an entity's Board of Directors or advisory committees; Dialectic: Membership on an entity's Board of Directors or advisory committees; Chugai: Other: Lecture Fees; Novartis: Research Funding; AbbVie: Consultancy; Zentalis: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy. Pullarkat:AbbVie, Inc.: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Dova: Consultancy, Honoraria; Genetech: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kantarjian:Immunogen: Research Funding; Janssen: Honoraria; Sanofi: Research Funding; BioAscend: Honoraria; Abbvie: Honoraria, Research Funding; Oxford Biomedical: Honoraria; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Aptitute Health: Honoraria; BMS: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Delta Fly: Honoraria; Pfizer: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Ascentage: Research Funding; Adaptive biotechnologies: Honoraria; Novartis: Honoraria, Research Funding; Jazz: Research Funding. Dail:Genentech: Current Employment, Current equity holder in publicly-traded company. Duan:AbbVie: Current Employment, Other: may hold stock or options. Chyla:AbbVie: Current Employment, Current equity holder in publicly-traded company. Potluri:AbbVie: Current Employment, Other: may hold stock or stock options. Miller:AbbVie: Current Employment, Current equity holder in publicly-traded company. Dinardo:Takeda: Honoraria; Daiichi Sankyo: Consultancy, Research Funding; Novartis: Consultancy; Notable Labs: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Research Funding; Celgene: Research Funding; Agios: Consultancy, Research Funding; Calithera: Research Funding; ImmuneOnc: Honoraria. Wei:AbbVie: Honoraria, Research Funding, Speakers Bureau; Servier: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; AstraZeneca: Honoraria, Research Funding; Pfizer: Honoraria; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria; Amgen: Honoraria, Research Funding; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties; Genetech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background: Sabatolimab (MBG453) is a high-affinity, humanized, IgG4 (S228P) antibody targeting TIM-3, an inhibitory receptor expressed on multiple immune cells and on leukemic stem/progenitor cells and blasts, but not on normal hematopoietic stem cells. Sabatolimab is being evaluated for treatment of patients (pts) with intermediate to very high risk MDS or AML in the STIMULUS clinical trial program. Here we report PK and clinical data supporting sabatolimab doses being evaluated in the STIMULUS program. Methods: PK analyses were done in a ph 1-1b/2 study in pts with adv solid tumors (NCT02608268) and a ph 1b study in pts with high/very high risk MDS (HR-MDS) or AML who were ineligible for intensive chemotherapy (NCT03066648). Pts with solid tumors received IV sabatolimab 80-1200 mg Q2W/Q4W or sabatolimab 20-800 mg Q2W/80-1200 mg Q4W + spartalizumab (PD-1 inhibitor). Based on findings in solid tumors, pts with HR-MDS/AML received IV sabatolimab 160-1200 mg Q2W/800 mg Q4W in treatment arms including sabatolimab monotherapy, + hypomethylating agent (HMA; decitabine [Dec] or azacitidine), and + spartalizumab (± Dec). Total sabatolimab serum concentration was used in population PK (popPK) modeling to simulate average (Cavg), maximal (Cmax), and trough (Ctrough) concentrations at steady state. Total serum soluble TIM-3 was measured and simulation was used to predict membrane-bound TIM-3 occupancy in the bone marrow (BM). PK exposure-response analysis (data cutoff 27 Nov 2019) and assessment of clinical safety/efficacy by dose (data cutoff 25 Jun 2020) were conducted in pts with HR-MDS/AML who received sabatolimab (dosed at 240 or 400 mg Q2W or 800 mg Q4W) + HMA. Results: Sabatolimab PK was similar for pts with solid tumors (n=252), HR-MDS, and AML (n=155 HR-MDS + AML); no drug-drug interactions were seen for any combinations. The estimated half-life of sabatolimab was ~16.7 days at linear PK dose levels and moderate accumulation was seen after multiple dosing. At lower doses (≤80 mg Q2W or ≤240 mg Q4W), sabatolimab exhibited nonlinear elimination indicative of target-mediated drug disposition, potentially related to internalization of the membrane-bound antibody-TIM-3 complex. At doses ≥240 mg Q2W and ≥800 mg Q4W, a plateau in the accumulated total soluble TIM-3 level was reached and PK approached a proportional dose-exposure relationship. Based on popPK modeling, among sabatolimab + HMA regimens 400 mg Q2W had the highest Ctrough at steady state, and 800 mg was predicted to be an equivalent Q4W dosing regimen. Both doses had similar steady state Cavg and similarly high occupancy rates for membrane-bound TIM-3 in the BM (>95% in ≥95% of pts with HR-MDS/AML), suggesting similarly high levels of TIM-3 engagement. PK exposure-safety analysis included 102 pts with HR-MDS/AML who received sabatolimab + HMA and were categorized into 4 exposure quartiles based on steady state Cmax and Cavg. There was no relationship between steady state Cmax or Cavg quartiles and incidence of treatment-related AEs. Similarly, exposure-efficacy analysis (n=92) showed no clear relationship between steady state Ctrough or Cavg and percent BM blast reduction or clinical benefit (CR/mCR/CRi/PR). The effect of sabatolimab dose on safety/efficacy was also evaluated in an updated clinical analysis in pts with HR-MDS/AML treated with sabatolimab + HMA. Overall, sabatolimab + HMA was safe and well tolerated with a low rate of study discontinuation due to AE (3.4% [4/116]). Rates of most common gr ≥3 treatment-emergent AEs and rates of gr ≥3 possible immune-mediated AEs related to study treatment did not appear to be dose dependent (Table). Among 35 evaluable pts with HR-MDS, CR/mCR/PR rates were 50.0%, 33.3% and 54.5% at sabatolimab doses of 240 mg Q2W, 400 mg Q2W and 800 mg Q4W. Among 60 evaluable pts with AML, CR/CRi/PR rates were 35.3%, 37.5% and 31.6%, respectively. There were no notable differences in responses across the 3 doses (Table). Conclusion: Sabatolimab 400 mg Q2W was predicted to have the highest steady state Ctrough and TIM-3 occupancy rate when combined with HMA, and 800 mg was predicted to be an equivalent Q4W dosing regimen. No clear relationship was seen between sabatolimab dose or steady state exposure and safety/efficacy at the doses tested. These results support clinical development of the sabatolimab 400 mg Q2W and 800 mg Q4W dosing regimens. Co-senior authors Andrew Brunner and Uma Borate contributed equally to the work. Table Disclosures Wei: AbbVie: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria; BMS: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria; Amgen: Honoraria, Research Funding; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties; Novartis: Honoraria, Research Funding, Speakers Bureau; Genetech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Honoraria, Research Funding; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Research Funding. Porkka:BMS/Celgene: Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Knapper:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Garcia-Manero:Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; Onconova: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; H3 Biomedicine: Research Funding; AbbVie: Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Jazz Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding; Amphivena Therapeutics: Research Funding. Wermke:MacroGenics: Honoraria. Janssen:MSD: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Roche: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Daiichi-Sankyo: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Takeda: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Janssen: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Abbvie: Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda; BMS: Other: Founder of the HematologyApp which is supported by Janssen, BMS, Incyte, MSD, Pfizer, Daiichi-Sankyo, Roche and Takeda, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Traer:Notable Labs: Consultancy, Current equity holder in private company; Genentech: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees. Narayan:Sanofi-Genzyme: Other: Current Spouse employment ; Takeda: Other: Prior Spouse employment within 24 months; Genentech: Other: Prior Spouse employment within 24 months and prior spouse equity divested within past 24 months. Kontro:Abbvie: Research Funding; Jazz Pharma: 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: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Ottmann:Amgen: Honoraria, Research Funding; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Fusion Pharma: Honoraria; Incyte: Honoraria, Research Funding. Liao:Novartis: Current Employment. Stein:Novartis: Current Employment, Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months. Khanshan:Novartis: Current Employment. Naidu:Novartis Pharmaceuticals: Current Employment. Zhang:Novartis: Current Employment. Rinne:Novartis: Current Employment; Qiagen: Consultancy. Sun:Novartis: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Brunner:Biogen: Consultancy; Acceleron Pharma Inc.: Consultancy; Celgene/BMS: Consultancy, Research Funding; Forty Seven, Inc: Consultancy; Jazz Pharma: Consultancy; Novartis: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Xcenda: Consultancy; GSK: Research Funding; Janssen: Research Funding; Astra Zeneca: Research Funding. Borate:Genentech: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Research Funding; AbbVie: Other: Investigator in AbbVie-funded clinical trials; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Background: Approximately 40-60% of older patients (pts) with AML achieve complete remission (CR) with IC. Factors influencing the use of consolidation after induction include disease-related considerations, extent of hematopoietic recovery, pt fitness, and physician and pt preference. Most older pts who achieve AML remission will experience disease relapse despite consolidation therapy (Schlenk, Haematologica, 2018). In the phase III, randomized, double-blind QUAZAR AML-001 Maintenance Trial, CC-486, an oral hypomethylating agent, was shown to significantly prolong OS and RFS vs. placebo (PBO) in pts with AML in first remission following induction ± consolidation. Prior to study entry, the use of consolidation chemotherapy and number of consolidation cycles was at the discretion of the treating physician, with study eligibility not contingent on the use of consolidation. Objective: Assess survival outcomes in the QUAZAR AML-001 trial in pt subgroups defined by number of consolidation courses received before study entry. Methods: Eligible pts were aged ≥55 years with newly diagnosed AML, intermediate- or poor-risk cytogenetics, and ECOG PS ≤3. Within 4 months (mo) of attaining first CR or CR with incomplete blood count recovery (CRi), pts were randomized 1:1 to CC-486 300 mg or PBO QD for 14 days per 28-day treatment (Tx) cycle. OS and RFS were compared among pts who received no consolidation ("No Consolidation"), 1 cycle of consolidation ("1 Consolidation"), or ≥2 cycles of consolidation ("≥2 Consolidations"). For these analyses, "induction" and "consolidation" defined regimens received before and after, respectively, the reported date of first CR/CRi. OS was defined as the time from randomization to death, and RFS as time from randomization to relapse or death. Kaplan-Meier OS/RFS estimates were compared for CC-486 vs. PBO using log-rank test. Hazard ratios (HRs) and 95% CIs were generated using a stratified Cox proportional hazards model. These analyses were not powered sufficiently to determine statistical significance. Results: 472 pts were randomized to CC-486 (N=238) or PBO (N=234). Most pts (80%) received consolidation before study entry. The No Consolidation cohort comprised 94 pts (20%; CC-486 52, PBO 42), the 1 Consolidation cohort comprised 212 pts (45%; CC-486 110, PBO 102), and the ≥2 Consolidations cohort comprised 166 pts (35%; CC-486 76, PBO 90), including 19 pts (CC-486 6, PBO 13) who received 3 consolidation cycles. Common agents used for consolidation were cytarabine (377/378 pts), idarubicin (95/378), and daunorubicin (37/378). While most pts received 1 induction, 97 pts received ≥2 induction courses; of them, 21 (CC-486 14, PBO 7) did not receive consolidation and 76 (CC-486 43, PBO 33) received ≥1 consolidation cycle. Baseline characteristics (eg, CR / CRi after IC, ECOG PS, cytogenetic risk at diagnosis) were generally similar among Tx arms and cohorts. Median (range) ages of pts in the 0 / 1 / ≥2 Consolidation cohorts were 71 (58-84), 68 (55-86), and 67 (55-82) years, respectively. In the No Consolidation cohort, median OS from the time of randomization with CC-486 vs. PBO was 23.3 vs. 10.9 mo, respectively (HR 0.55 [95%CI 0.34, 0.89]), and median RFS was 8.4 vs. 3.9 mo (0.55 [0.34, 0.88]) (Figure A). In the 1 Consolidation cohort, median OS was 21.0 vs. 14.3 mo with CC-486 vs. PBO, respectively (HR 0.75 [95%CI 0.55, 1.02]), and median RFS was 10.0 vs. 4.7 mo (0.72 [0.53, 0.99]) (Figure B). In the ≥2 Consolidations cohort, median OS was 28.6 mo with CC-486 vs. 17.6 mo with PBO (HR 0.75 [95%CI 0.50, 1.11]), and median RFS was 13.0 vs. 6.1 mo (0.59 [0.41, 0.87]) (Figure C). Conclusions: CC-486 was associated with consistent survival benefits vs. PBO regardless of number of prior consolidation cycles. Use of consolidation was generally associated with nominal improvements in OS and RFS within each Tx arm; however, in the CC-486 arm, median OS for pts who did not receive consolidation was similar to those who received 1 consolidation cycle (23.3 and 21.0 mo, respectively). Results should be interpreted with caution, as these cohorts were not prospectively defined and the study was not powered to detect significant differences between subgroups. Nevertheless, these data clearly suggest that older pts with AML in first remission after induction can benefit from CC-486, regardless of their fitness to receive consolidation or the number of consolidation cycles received before starting CC-486. Disclosures Wei: AMGEN: Honoraria, Other: Advisory committee, Research Funding; Walter and Eliza Hall Institute: Patents & Royalties; Novartis: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria, Other: Advisory committee, Research Funding, Speakers Bureau; Genentech: Honoraria, Other: Advisory committee; Servier: Consultancy, Honoraria, Other: Advisory committee; Astellas: Honoraria, Other: Advisory committee; Pfizer: Honoraria, Other: Advisory committee; Macrogenics: Honoraria, Other: Advisory committee; Celgene: Honoraria, Other: Advisory committee, Speakers Bureau; Astra-Zeneca: Honoraria, Other: Advisory committee, Research Funding; Janssen: Honoraria, Other. Roboz:Orsenix: Consultancy; Actinium: Consultancy; Argenx: Consultancy; Jazz: Consultancy; Astex: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Pfizer: Consultancy; Bayer: Consultancy; Array BioPharma: Consultancy; Abbvie: Consultancy; Agios: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy; AstraZeneca: Consultancy; Jasper Therapeutics: Consultancy; Cellectis: Research Funding; Otsuka: Consultancy; Takeda: Consultancy; Trovagene: Consultancy; Eisai: Consultancy; Celltrion: Consultancy; Epizyme: Consultancy; Helsinn: Consultancy; MEI Pharma: Consultancy; Sandoz: Consultancy; Roche/Genentech: Consultancy; Amphivena: Consultancy. Dombret:Sunesis: Consultancy; Abbvie: Consultancy; Shire-Baxalta: Consultancy; Immunogen: Consultancy; Otsuka: Consultancy; Janssen: Consultancy; Menarini: Consultancy; Pfizer: Consultancy, Research Funding; Jazz Pharma: Consultancy, Research Funding; Celgene: Consultancy; Nova: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Astellas: Consultancy; Servier: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Daiichi Sankyo: Consultancy; Cellectis: Consultancy. Döhner:Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Astex: Consultancy, Honoraria; Astellas: Consultancy, Honoraria, Research Funding; AROG: Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Sunesis: Research Funding; Oxford Biomedicals: Consultancy, Honoraria; Pfizer: Research Funding; Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Helsinn: Consultancy, Honoraria; Jazz: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; GEMoaB: Consultancy, Honoraria. Selleslag:Amgen: Consultancy, Honoraria, Speakers Bureau; MSD: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Incyte: Consultancy, Honoraria; GSK: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Alexion: Consultancy, Honoraria; Astellas: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Janssen Cilag: Consultancy, Honoraria, Speakers Bureau; AbbVie: Consultancy, Honoraria, Speakers Bureau; Belgian College: Membership on an entity's Board of Directors or advisory committees; Teva: Consultancy, Honoraria, Speakers Bureau; Takeda: Consultancy, Honoraria, Speakers Bureau. La Torre:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Skikne:Bristol Myers Squibb: Current Employment. Kumar:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Dong:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Beach:Bristol Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Ravandi:Macrogenics: Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Orsenix: Consultancy, Honoraria, Research Funding; Xencor: Consultancy, Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria.

Ivosidenib (AG-120) and enasidenib (AG-221) are targeted oral inhibitors of the mutant isocitrate dehydrogenase (mIDH) 1 and 2 enzymes, respectively. Given their effectiveness as single agents in mIDH1/2 relapsed or refractory acute myeloid leukemia (AML), this phase 1 study evaluated the safety and efficacy of ivosidenib or enasidenib combined with intensive chemotherapy in patients with newly diagnosed mIDH1/2 AML. Ivosidenib 500 mg once daily and enasidenib 100 mg once daily were well tolerated in this setting, with safety profiles generally consistent with those of induction and consolidation chemotherapy alone. The frequency of IDH differentiation syndrome was low, as expected given the concurrent administration of cytotoxic chemotherapy. In patients receiving ivosidenib, the frequency and grades of QT interval prolongation were similar to those observed with ivosidenib monotherapy. Increases in total bilirubin were more frequently observed in patients treated with enasidenib, consistent with this inhibitor's known potential to inhibit UGT1A1, but did not appear to have significant clinical consequences. In patients receiving ivosidenib (n = 60) or enasidenib (n = 91), end-of-induction complete remission (CR) rates were 55% and 47%, respectively, and CR/CR with incomplete neutrophil or platelet recovery (CR/CRi/CRp) rates were 72% and 63%, respectively. In patients with a best overall response of CR/CRi/CRp, 16/41 (39%) receiving ivosidenib had IDH1 mutation clearance and 15/64 (23%) receiving enasidenib had IDH2 mutation clearance by digital polymerase chain reaction; furthermore, 16/20 (80%) and 10/16 (63%), respectively, became negative for measurable residual disease by multiparameter flow cytometry. This trial was registered at www.clinicaltrials.gov as #NCT02632708.

Older patients with acute myeloid leukemia (AML) respond poorly to standard induction therapy. B-cell lymphoma 2 (BCL-2) overexpression is implicated in survival of AML cells and treatment resistance. We report safety and efficacy of venetoclax with decitabine or azacitidine from a large, multicenter, phase 1b dose-escalation and expansion study. Patients (N = 145) were at least 65 years old with treatment-naive AML and were ineligible for intensive chemotherapy. During dose escalation, oral venetoclax was administered at 400, 800, or 1200 mg daily in combination with either decitabine (20 mg/m2, days 1-5, intravenously [IV]) or azacitidine (75 mg/m2, days 1-7, IV or subcutaneously). In the expansion, 400 or 800 mg venetoclax with either hypomethylating agent (HMA) was given. Median age was 74 years, with poor-risk cytogenetics in 49% of patients. Common adverse events (>30%) included nausea, diarrhea, constipation, febrile neutropenia, fatigue, hypokalemia, decreased appetite, and decreased white blood cell count. No tumor lysis syndrome was observed. With a median time on study of 8.9 months, 67% of patients (all doses) achieved complete remission (CR) + CR with incomplete count recovery (CRi), with a CR + CRi rate of 73% in the venetoclax 400 mg + HMA cohort. Patients with poor-risk cytogenetics and those at least 75 years old had CR + CRi rates of 60% and 65%, respectively. The median duration of CR + CRi (all patients) was 11.3 months, and median overall survival (mOS) was 17.5 months; mOS has not been reached for the 400-mg venetoclax cohort. The novel combination of venetoclax with decitabine or azacitidine was effective and well tolerated in elderly patients with AML (This trial was registered at www.clinicaltrials.gov as #NCT02203773).

Less-intensive induction therapies are increasingly used in older patients with acute myeloid leukemia (AML). Using an AML composite model (AML-CM) assigning higher scores to older age, increased comorbidity burdens, and adverse cytogenetic risks, we defined 3 distinct prognostic groups and compared outcomes after less-intensive vs intensive induction therapies in a multicenter retrospective cohort (n = 1292) treated at 6 institutions from 2008 to 2012 and a prospective cohort (n = 695) treated at 13 institutions from 2013 to 2017. Prospective study included impacts of Karnofsky performance status (KPS), quality of life (QOL), and physician perception of cure. In the retrospective cohort, recipients of less-intensive therapies were older and had more comorbidities, more adverse cytogenetics, and worse KPS. Less-intensive therapies were associated with higher risks of mortality in AML-CM scores of 4 to 6, 7 to 9, and ≥10. Results were independent of allogeneic transplantation and similar in those age 70 to 79 years. In the prospective cohort, the 2 groups were similar in baseline QOL, geriatric assessment, and patient outcome preferences. Higher mortality risks were seen after less-intensive therapies. However, in models adjusted for age, physician-assigned KPS, and chance of cure, mortality risks and QOL were similar. Less-intensive therapy recipients had shorter length of hospitalization (LOH). Our study questions the survival and QOL benefits (except LOH) of less-intensive therapies in patients with AML, including those age 70 to 79 years or with high comorbidity burdens. A randomized trial in older/medically infirm patients is required to better assess the value of less-intensive and intensive therapies or their combination. This trial was registered at www.clinicaltrials.gov as #NCT01929408.

Contains fulltext : 218279.pdf (Publisher’s version ) (Open Access) Patients with acute myeloid leukemia (AML) harboring FLT3 internal tandem duplications (ITDs) have poor outcomes, in particular AML with a high (>/=0.5) mutant/wild-type allelic ratio (AR). The 2017 European LeukemiaNet (ELN) recommendations defined 4 distinct FLT3-ITD genotypes based on the ITD AR and the NPM1 mutational status. In this retrospective exploratory study, we investigated the prognostic and predictive impact of the NPM1/FLT3-ITD genotypes categorized according to the 2017 ELN risk groups in patients randomized within the RATIFY trial, which evaluated the addition of midostaurin to standard chemotherapy. The 4 NPM1/FLT3-ITD genotypes differed significantly with regard to clinical and concurrent genetic features. Complete ELN risk categorization could be done in 318 of 549 trial patients with FLT3-ITD AML. Significant factors for response after 1 or 2 induction cycles were ELN risk group and white blood cell (WBC) counts; treatment with midostaurin had no influence. Overall survival (OS) differed significantly among ELN risk groups, with estimated 5-year OS probabilities of 0.63, 0.43, and 0.33 for favorable-, intermediate-, and adverse-risk groups, respectively (P < .001). A multivariate Cox model for OS using allogeneic hematopoietic cell transplantation (HCT) in first complete remission as a time-dependent variable revealed treatment with midostaurin, allogeneic HCT, ELN favorable-risk group, and lower WBC counts as significant favorable factors. In this model, there was a consistent beneficial effect of midostaurin across ELN risk groups.

Effective treatment options are limited for patients with acute myeloid leukemia (AML) who cannot tolerate intensive chemotherapy. Adults age ≥18 years with newly diagnosed AML ineligible for intensive chemotherapy were enrolled in this international phase 3 randomized double-blind placebo-controlled trial. Patients (N = 211) were randomized 2:1 to venetoclax (n = 143) or placebo (n = 68) in 28-day cycles, plus low-dose cytarabine (LDAC) on days 1 to 10. Primary end point was overall survival (OS); secondary end points included response rate, transfusion independence, and event-free survival. Median age was 76 years (range, 36-93 years), 38% had secondary AML, and 20% had received prior hypomethylating agent treatment. Planned primary analysis showed a 25% reduction in risk of death with venetoclax plus LDAC vs LDAC alone (hazard ratio [HR], 0.75; 95% confidence interval [CI], 0.52-1.07; P = .11), although not statistically significant; median OS was 7.2 vs 4.1 months, respectively. Unplanned analysis with additional 6-month follow-up demonstrated median OS of 8.4 months for the venetoclax arm (HR, 0.70; 95% CI, 0.50-0.98; P = .04). Complete remission (CR) plus CR with incomplete blood count recovery rates were 48% and 13% for venetoclax plus LDAC and LDAC alone, respectively. Key grade ≥3 adverse events (venetoclax vs LDAC alone) were febrile neutropenia (32% vs 29%), neutropenia (47% vs 16%), and thrombocytopenia (45% vs 37%). Venetoclax plus LDAC demonstrates clinically meaningful improvement in remission rate and OS vs LDAC alone, with a manageable safety profile. Results confirm venetoclax plus LDAC as an important frontline treatment for AML patients unfit for intensive chemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT03069352.

Although the BCL2 inhibitor venetoclax have been transformative in the management of AML, therapeutic resistance and relapse are frequently observed. In light of the urgent need to uncover novel therapeutic options in AML, we sought to study the potential role of ironomycin (AM5), a recently described small molecule that induces cell death through the sequestration of lysosomal iron. To evaluate the effects of ironomycin in AML, we chose a diverse panel of AML cell lines. These data showed a potent and dose-dependent effect, on proliferation, cell cycle progression and survival at a nanomolar range. In contrast to venetoclax, the cell death induced by ironomycin did not result in potent caspase activation or PARP1 cleavage. Neither the caspase inhibitor Z-VAD-fmk nor the necroptosis inhibitor necrostatin-1 did prevent cell death. Consistent with previous observations, we found that ironomycin accumulates in the lysosomes of AML cells leading to a sequestration of iron in this organelle but inhibitors of canonical ferroptosis, including ferrostatin-1 and liproxstatin-1 failed to prevent the activity of ironomycin. To gain greater insight into the molecular mechanism of ironomycin in AML cells, we performed a genome-wide positive-selection resistance screen under ironomycin selection pressure and collected several samples for sequencing. We found nine genes whose knock out conferred resistance to the drug. Interestingly, these data implicated key components of mitochondrial metabolic pathways, including phosphoglycolate phosphatase (PGP), a central phosphatase involved in glycolysis and pentose phosphate pathway (PPP) regulation and Hexokinase 2 (HK2), the first enzyme of glycolysis. Mass-spectrometry metabolomics analyses highlighted that ironomycin treatment significantly reduced key components of the TCA cycle and consequently the reducing agent nicotinamide adenine dinucleotide (NADH) and increased the intracellular concentration of amino acids. These data were corroborated with RNAseq showing a mitochondrial stress response mediated through the Activating Transcription Factor 4 (ATF4) and its paralog Activating Transcription Factor 5 (ATF5). As mitochondria are major hubs of iron utilization for oxidative respiration, we used Mass-spectrometry to measure mitochondrial iron load. We observed a rapid and dose-dependent decrease in mitochondrial iron after treatment mirroring the iron sequestration into the lysosomes and inducing the mitochondrial dysfunction. We next examined the ultrastructural appearance of mitochondria after ironomycin using transmission electron microscopy and observed a dramatic alteration of the structural integrity of mitochondria resulting in abnormal cristae, matrix density changes and mitochondrial membrane blebbing. In cells lacking BAX and BAK, the two main effectors of mitochondrial membrane permeabilization, structural changes and cell death were almost completely rescued but cell proliferation was still markedly affected, consistent with a BAX/BAK dependent cell death following mitochondrial iron deprivation. In vivo imaging confirmed that BAX activation occurred after 30 hours of treatment and preceded cell death, but we observed some major differences with canonical apoptosis induced by venetoclax. First, the structural alterations were clearly distinct. Next, delay between MOMP and cell death was significantly longer and caspase inhibitors weakly delayed cell death. Finally, BCL2 overexpression and P53 deletion did not rescue ironomycin cell death. These non-canonical features prompted us to assess the efficacy of the combination between ironomycin and venetoclax. In vitro experiment on AML cell lines found a high synergy between the two drugs. In vivo experiments on xenotransplanted mice confirmed the efficacy of the combination, which was associated with a significant increase in mice survival in comparison with the controls (Figure). Finally, primary AML samples from patients clinically resistant or refractory to venetoclax were sensitive to ironomycin in monotherapy and even more in combination with venetoclax. These results demonstrate that the novel mechanism of ironomycin action can be leveraged to resensitize AML cells to venetoclax and substitute for cytotoxic drugs as a more effective therapeutic combination in the salvage setting. Figure 1 Figure 1. Disclosures Huang: The Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: Employee of the Walter and Eliza Hall Institute and eligilble for payments in relation to venetoclax. Wei: Novartis, Celgene, AbbVie, Servier, AstraZeneca, and Amgen: Research Funding; Novartis, Janssen, Amgen, Roche, Pfizer, Abbvie, Servier, BMS, Macrogenics, Agios, Gilead: Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria.

The advent of pediatric inspired regimens has improved the outcome for younger adults with Acute Lymphoblastic Leukemia (ALL), however this comes at a considerable toxicity burden limiting its applicability in older adults. The advent of novel immunotherapies, such as Blinatumomab, an anti-CD19 targeting Bi-specific T-cell engager, has improved outcomes for adults with relapsed refractory and minimal residual disease (MRD) positive B-precursor (BCP) ALL. The Australasian Leukemia and Lymphoma Group (ALLG) undertook a phase 2 proof-of-concept study to explore the combination of Blinatumomab with reduced intensity chemotherapy in adults with newly diagnosed Ph- BCP ALL. Patients received an initial pre-phase of corticosteroids (Prednisolone 100mg/d, 5 days) followed by a low intensity chemotherapy debulking (Cyclophosphamide 150mg/m 2 BD D1-3, Vincristine 2mg IV D1, 11 and Dexamethasone 10mg/m 2 D1-4, D11-14). Following this patients received Blinatumomab at 9mcg/d days 1-7 and 28mcg/d days 8-28. A B cycle of Hyper-CVAD (Cytarabine 3g/m 2 BD for 4 doses and Methotrexate 1g/m 2 D1 with Methylprednisolone 50mg BD D1-3). Patients then received 3 alternating cycles of Blinatumomab (28mcg/d for 28 days) and B-cycles of Hyper-CVAD followed by 2-years of POMP maintenance in subjects not proceeding to allogeneic stem cell transplant (alloHSCT) which was at investigator discretion. MRD assessments by ASO-PCR were performed after the first B cycle, second B cycle and prior to maintenance therapy with an MRD response being a level of 10 -4 or less. This analysis is from a pre-specified interim analysis with a data cutoff of 29 th June 2021. 30 patients were enrolled with a median age of 51.7(range, 39.5 - 66.5 years) with 70% male subjects. ECOG performance score was 0 in 14 subjects, 1 in 12 and 2 in 4. High risk disease was identified in 5 subjects (1 t(4;11), 2 hypodiploid, 1 t(1;19) and 1 Ph-like). All patients attained a CR, with 28 at end of 1B and a further 2 at end of 2B. Of 26 patients evaluable for MRD, 70% had achieved an MRD response after cycle 1B and 83% at the end of cycle 2B. 15 patients have ceased study therapy; 6 patients died with progressive disease, 4 subjects exited to allogeneic stem cell transplant, 1 patient was withdrawn due to progressive disease, 1 had intolerable toxicity (peripheral neuropathy) and 1 at investigator discretion. There were no treatment related deaths. 15 remain on protocol in maintenance with the remainder having completed therapy. At data cut-off the median event free survival (EFS) was not reached (95% CI 8.3 months - NA) with an estimated 24 month EFS of 61.8% (95% CI 36.3 - 84.2%) (figure 1A), and similarly the median overall survival (OS) S was not reached (95% CI 21.0 months - NA) with an estimated 24 month OS of 68.6% (95% CI 41.5 - 85.1%)(figure 1B). This predicted EFS was greater than the pre-specified stopping rule of a 24-month EFS of 50%. 2 episodes of cytokine release syndrome (CRS) were recorded (1 grade 2, 1 grade 3) with the major toxicity being infective (53 episodes of sepsis, infection or febrile neutropenia) predominately related to chemotherapy cycles. 7 episodes of neurological toxicity were demonstrated (1 myelopathy and 4 peripheral neuropathy occurring during chemotherapy and 2 encephalopathy occurring during Blinatumomab administration). Overall, the combination of Blinatumomab with chemotherapy was tolerable and appeared efficacious with a high rate of remission and deep MRD responses observed. Responses appeared durable despite a low rate of alloHSCTin first remission. The major toxicity was infective and occurred in the context of chemotherapy cycles. Future developments from this protocol will emphasise further reduction in cytotoxic chemotherapy through incorporation of further novel agents to minimise this toxicity. Figure 1 Figure 1. Disclosures Fleming: Servier: Honoraria; Pfizer: Honoraria, Speakers Bureau; Abbvie: Honoraria, Speakers Bureau; Amgen: Honoraria, Research Funding, Speakers Bureau. Reynolds: Abbvie: Research Funding; Novartis AG: Current equity holder in publicly-traded company; Alcon: Current equity holder in publicly-traded company. Bajel: Abbvie, Amgen, Novartis, Pfizer: Honoraria; Amgen: Speakers Bureau. Yeung: BMS: Honoraria, Research Funding; Pfizer: Honoraria; Amgen: Honoraria; Novartis: Honoraria, Research Funding. Verner: Janssen-Cilag Pty Ltd: Research Funding. Wei: Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Honoraria; Novartis, Abbvie, Celgene/BMS: Speakers Bureau; Servier: Consultancy; Abbvie, Amgen, AstraZeneca, Celgene/BMS, Novartis, Servier and F. Hoffmann-La Roche: Research Funding; Abbvie, Amgen, Astellas, AstraZeneca, Celgene/BMS, Genentech, Janssen, MacroGenics, Novartis, Pfizer, and Servier: Membership on an entity's Board of Directors or advisory committees; Former employee of Walter and Eliza Hall Institute: Patents & Royalties: Prof. Andrew Wei is a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax. Greenwood: Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Blinatumomab - usage in front-line therapy for Acute Lymphoblastic Leukaemia

Background: Olutasidenib is a potent, selective, oral, small molecule inhibitor of mutant IDH1 (mIDH1). Olutasidenib has previously shown clinical activity in high-risk AML patients (pts) in a Phase 1 clinical trial (Watts, Blood 2019). The planned interim analysis of an ongoing Phase 2 clinical trial (NCT02719574) in R/R mIDH1 AML pts receiving single-agent olutasidenib 150 mg twice-daily showed an overall response rate (ORR) of 46%, including 33% of pts with CR/CRh (de Botton et al., ASCO/EHA 2021). Here we present data analysis on the mutational characteristics of these pts and the relationship between mutations and clinical response. Methods: The Efficacy Evaluable (EE) set comprised mIDH1R132X pts whose first dose was ≥180 days before the data cut-off (18-JUN-20). The primary endpoint was CR/CRh (complete remission [CR] according to modified IWG 2003 criteria plus CR with partial hematologic recovery [CRh]) response rate. CRh was defined as bone marrow blasts 0.5×10 9/L, and platelet count >50×10 9/L. ORR, a secondary endpoint, comprised CR+CRh+CR with incomplete recovery (CRi) + morphologic leukemia-free state (MLFS) + partial remission (PR). IDH1 mutation subtypes were determined by central analysis, co-mutations were reported by investigators. Baseline characteristics and mutation subtypes were tabulated for the safety population and analysis of response rate by mutation type was performed on the EE set. Results: There were 153 R/R AML pts treated with olutasidenib 150 mg BID (safety set). Of those, 123 were in the efficacy evaluable (EE) set (centrally confirmed IDH1R132 mutation and received first dose at least 180 days prior to the data cut off). For the safety population, cytogenetic risk classification was favorable in 6 (4%) pts, intermediate in 109 (71%) pts, and poor in 25 (16%) pts (unknown, 13 [8%] pts). Eighty-five (56%) pts had IDH1R132C mutation subtype, followed by IDH1R132H (n=35 [23%]), IDH1R132G (n=12 [8%]), IDH1R132S (n=11 [7%]), and IDH1R132L (n=4 [3%]). Ninety-four (61%) pts had 1-3 co-mutations reported by the investigator at baseline, with 4-7 co-mutations in 20 (13%) pts, none in 6 (4%) pts, and not done/unknown in 33 (22%) pts. The most common co-mutations at baseline were: NPM1 (n=40 [26%]), DNMT3A (n=36 [24%]), and ASXL1 (n=21 [14%]. Receptor tyrosine kinase (RTK) mutations were reported in 32 (21%) pts (FLT3, n=18 [12%]; NRAS, n=10 [7%]; KRAS, n=3 [2%]; PTPN11, n=3 [2%]; KIT, n=2 [1%]; NF1, n=2 [1%]), with multiple mutations reported in some pts. For the EE population, responses were achieved in all IDH1R132 mutation subtypes, with ORR and CR/CRh response rates ranging from 27%-54% and 17%-50%, respectively (Table 1). The CR/CRh response rate was lower for pts with IDH1R132H mutations; notably, these pts tended to have a higher percentage of co-mutations, particularly mutations in NPM1 and RTK genes, including FLT3. For EE pts with available co-mutation data (n=96), the mean (SD) number of co-mutations was lower (p Conclusions: Responses were observed across IDH1R132 mutation subtypes, with a relatively lower CR/CRh response rate for pts with a R132H mutation as compared to other subtypes. Pts with a best response of CR/CRh had fewer co-mutations than pts who did not achieve CR/CRh. While the ORR was not significantly reduced for pts with RTK mutations, these pts had a lower CR/CRh response rate compared to pts without any RTK mutations. Additional genetic analyses using ddPCR for IDH1 mutations and NGS on a targeted panel of genes at baseline, best response, and end of study will be presented to further explore primary and secondary resistance mechanisms. Figure 1 Figure 1. Disclosures De Botton: Celgene, Agios, Forma Therapeutics, Astella, Daiichi Sankyo, Syros, Abbvie, Bayer, Seattle Genetics, Janssen: Honoraria; Celgene, Agios, Astellas, Daiichi Sankyo, Syros, Abbvie, Bayer, Janssen, Pierre Fabre, Novartis, Pfizer, Servier: Consultancy; Celgene: Speakers Bureau; Agios, Forma Therapeutics: Research Funding. Yee: Forma Therapeutics: Research Funding; Onconova: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MedImmune: Research Funding; Jazz: Research Funding; Tolero: Research Funding; AbbVie: Honoraria; F. Hoffmann La Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Geron: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; TaiHo: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Paladin: Membership on an entity's Board of Directors or advisory committees; Otsuka: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb/Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Astex: Membership on an entity's Board of Directors or advisory committees, Research Funding. Recher: BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; Janssen: Honoraria; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MaatPharma: Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Wei: Gilead: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Montesinos: Forma Therapeutics: Consultancy; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Tolero Pharmaceutical: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Glycomimetics: Consultancy; Stemline/Menarini: Consultancy; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau. Pigneux: Amgen: Consultancy; Sunesis: Consultancy, Research Funding; BMS Celgene: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Braun: Servier: Research Funding; Daiichi-Sankyo, Celgene: Consultancy, Honoraria. Curti: Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Esteve: Novartis: Consultancy, Research Funding; Jazz: Consultancy; Pfizer: Consultancy; Astellas: Consultancy; Novartis: Research Funding; Bristol Myers Squibb/Celgene: Consultancy; Abbvie: Consultancy. Grove: Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jonas: 47, AbbVie, Accelerated Medical Diagnostics, Amgen, AROG, Celgene, Daiichi Sankyo, F. Hoffmann-La Roche, Forma, Genentech/Roche, Gilead, GlycoMimetics, Hanmi, Immune-Onc, Incyte, Jazz, Loxo Oncology, Pfizer, Pharmacyclics, Sigma Tau, Treadwell: Research Funding; AbbVie, BMS, Genentech, GlycoMimetics, Jazz, Pfizer, Takeda, Treadwell: Consultancy; AbbVie: Other: Travel reimbursement. Khwaja: Pfizer, Abbvie: Honoraria; Novartis, Jazz: Speakers Bureau. Blum: Forma Therapeutics, Xencor; Celyad: Research Funding; Amerisource Bergen; Abbvie, Syndax: Honoraria. Hiwase: Novartis: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Jurcic: AbbVie, BMS/Celgene, Novartis: Consultancy; AbbVie, Arog Pharmaceuticals, Astellas, BMS/Celgene, Forma Therapeutics, Genentech, Gilead Sciences, PTC Therapeutics, Syros Pharmaceuticals: Research Funding. Watts: Rafael Pharmaceuticals: Consultancy; Genentech: Consultancy; Bristol Myers Squibb: Consultancy; Takeda: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Aptevo Therapeutices: Research Funding. Xin: Forma Therapeutics, Inc.: Current Employment. Sedkov: Forma Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Guichard: Forma Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Sweeney: Forma Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Cortes: Sun Pharma: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Bristol Myers Squibb, Daiichi Sankyo, Jazz Pharmaceuticals, Astellas, Novartis, Pfizer, Takeda, BioPath Holdings, Incyte: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Bio-Path Holdings, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding. Fenaux: Syros Pharmaceuticals: Honoraria; JAZZ: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding.

Background: Treatment options for patients (pts) with relapsed/refractory (r/r) AML and HR-MDS who cannot tolerate standard therapy are limited, and innovative combination approaches are needed. Dysregulation of the tumor protein 53 [p53, (TP53 gene)], Murine Double Minute-2 (MDM2) interaction leads to uncontrolled cell proliferation and tumor growth (Chene 2003). Siremadlin is an orally administered small molecule inhibitor of the p53-MDM2 interaction, which has a well-characterized safety profile and shows antitumor activity in pts with AML (Stein 2021). Combination of siremadlin with BCL-2 inhibitors (eg, venetoclax [VEN]) results in synergistic activity in p53 wild-type AML cell lines and leads to complete and durable antitumor responses in a variety of p53wt AML patient-derived xenograft models (Wang 2019). Thus, combined MDM2 and BCL-2 inhibition may result in improved outcomes for pts with hematologic malignancies. Here we report the preliminary results of a phase Ib, open-label study of siremadlin in combination with VEN for the treatment of pts with AML and HR- MDS (NCT03940352). Methods: Pts were adults with r/r AML after ≥1 but ≤3 prior therapies who were not suited for standard therapy, or pts with AML who were unfit for standard chemotherapy. HR-MDS pts (per Revised International Prognostic Scoring System) who have previously failed hypomethylating agent therapy were also eligible. AML pts with TP53-mutant tumors (determined as the presence of any mutations in exons 5,6,7, and 8 at minimum) were excluded. Pts with prior treatment with an MDM2 or MDM4 inhibitor in combination with a BCL-2 inhibitor were excluded. Siremadlin (20 or 30 mg) was administered daily from day 1-5 during each 28-day cycle in combination with VEN at a starting dose of 50 mg daily, followed by a gradual ramp-up period over 4 days to a target daily dose of 400 mg (dose level [DL] 1: siremadlin 20 mg + VEN and DL2: siremadlin 30 mg + VEN]. Pts continued study treatment until unacceptable toxicity, disease progression, or investigator/patient decision. The primary objective is to evaluate safety/tolerability; secondary objectives are to test preliminary efficacy (per Cheson 2003) and pharmacokinetics (PK). Results: As of data cutoff March 1, 2021, 18 total pts underwent treatment. The median age was 72.5 y (range, 29-84). Most pts had an Eastern Cooperative Oncology Group performance status of 0 (n=13, 72%). Of the 17 (94%) pts with AML, 3 pts had first-line and 14 pts had r/r AML. One (6%) pt had HR-MDS (DL1); efficacy data for this pt are not presented. Eleven pts were treated at DL1 and 7 at DL2. Treatment is ongoing for 2 pts (both DL2). The mean treatment duration was 3.8 mo (range, 0.9-10.3; DL1) and 1.8 mo (range, 0-3.8; DL2). Two pts (DL1) had ≥9 mo treatment duration. The most common grade ≥3 adverse events (AEs) suspected to be treatment-related were neutropenia (n=5, 28%) and thrombocytopenia (n=4, 22%); 11 pts (61.1%) experienced grade ≥3 serious AEs regardless of study-treatment; only febrile neutropenia was experienced by >20% of pts (n=8, 44%). One case of tumor lysis syndrome was reported. Notably, gastrointestinal grade ≥3 serious AEs were uncommon (diarrhea [n=2, 11%] and nausea [n=1, 6%]). Dose modification or interruption due to an AE occurred in 10 (56%) pts, mostly due to febrile neutropenia (n=4) and neutropenia (n=3), and discontinuation due to an AE occurred in 4 (22%) pts, mostly due to febrile neutropenia (n=2). Among the 11 pts in the dose-determining set, 2 experienced dose limiting toxicities (1 with anemia, bone marrow failure, and thrombocytopenia and 1 with febrile neutropenia). Two on-treatment deaths occurred; however, none were treatment-related. Among 10 pts with AML in DL1, 1 had complete remission (CR), 3 had CR with incomplete blood count recovery (CRi) and had 1 partial remission. Among 7 pts with AML in DL2, 3 pts had CRi (Table). One pt in DL2 currently has an ongoing CRi. PK exposure and parameters for siremadlin and VEN for both cohorts were comparable to historical single-agent data. No drug-drug interaction between siremadlin and VEN was observed. Conclusions: Siremadlin + VEN is well-tolerated in pts with AML and shows promising antileukemic activity in r/r AML pts. These results validate the MDM2-p53 interaction as a therapeutic target and provide support for further development of siremadlin + VEN in pts with AML or HR-MDS. Dose escalation is ongoing to determine the recommended dose for expansion. Figure 1 Figure 1. Disclosures Wei: Astellas: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Breccia: Pfizer: Honoraria; Novartis: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Bristol Myers Squibb/Celgene: Honoraria. Cedena Romero: Janssen: Honoraria; BMS: Honoraria. Ciceri: IRCCS Ospedale San Raffaele: Current Employment. Erba: AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau; AbbVie Inc: Other: Independent review committee; AbbVie Inc; Agios Pharmaceuticals Inc; Astellas; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Daiichi Sankyo Inc; Genentech, a member of the Roche Group; GlycoMimetics Inc; Incyte Corporation; Jazz Pharmaceuticals Inc; Kura Oncology; Nov: Other: Advisory Committee; AbbVie Inc; Agios Pharmaceuticals Inc; ALX Oncology; Amgen Inc; Daiichi Sankyo Inc; FORMA Therapeutics; Forty Seven Inc; Gilead Sciences Inc; GlycoMimetics Inc; ImmunoGen Inc; Jazz Pharmaceuticals Inc; MacroGenics Inc; Novartis; PTC Therapeutics: Research Funding. Gaur: Novartis: Current Employment. Sechaud: Novartis: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Halilovic: Novartis: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Kuenzle: Novartis: Current Employment. Fabre: Novartis: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. OffLabel Disclosure: Siremadlin is a small molecule inhibitor of the p53-MDM2 interaction under investigation for the treatment of patients with myeloid malignancies.

Background: Adaptive resistance mechanisms leading to treatment failure have been identified in older patients receiving venetoclax (VEN) in combination with either azacitidine or low dose cytarabine (LDAC) as frontline therapy for acute myeloid leukemia (AML). These include the expansion or secondary emergence of kinase activating mutations, including FLT3-ITD in patients with non-adverse karyotype (NON-ADV), as well as TP53 mutations among patients with adverse karyotype (ADV)(DiNardo & Tiong et al, Blood 2020). INTERVENE is a phase 2 study evaluating the safety and efficacy of the "risk-stratified" addition of a novel third agent to VEN-LDAC, delivered in tandem to LDAC to minimize the risk of myelotoxicity (Figure 1A). To mitigate VEN resistance associated with activated kinases in NON-ADV risk AML, midostaurin (MIDO), a FLT3/multi-kinase inhibitor, was incorporated in combination with VEN. To address VEN resistance associated with TP53 defects in ADV risk AML, a HDAC inhibitor pracinostat (PRAN) was incorporated in accordance with pre-clinical studies suggesting synergistic induction of TP53 independent cell death with VEN plus HDAC inhibition (Salmon et al, ASH 2018). We hereby report the results of the dose-finding safety run-in phase of the study. Methods: Eligibility: Patients with treatment naïve AML (excluding APL), aged ≥60 years and unfit for intensive chemotherapy were included. Prior hypomethylating agents for antecedent myeloid neoplasms were permitted with a 14-day washout. Patients were stratified according to cytogenetic risk, as per Medical Research Council 2010 criteria. Treatment: VEN D1-28 (with dose ramp-up in cycle 1) was combined with LDAC (20mg/m 2 SC D1-10), with the third agent starting after/on the last day of LDAC (Fig 1A). Each cycle was 28 days. In the NON-ADV stratum (VEN-LDAC-MIDO), 2 dose levels were explored: (L1) VEN 400mg + LDAC + MIDO 50mg BD D11-28; (L2) VEN 600mg + LDAC + MIDO 50mg. In the ADV stratum (VEN-LDAC-PRAN), 3 dose levels were tested: (L1) VEN 400mg + LDAC + PRAN 45mg starting D10 and given 3x/week orally for a total of 9 doses; (L2) VEN 600mg + LDAC + PRAN 45mg; (L3) VEN 600mg + LDAC + PRAN 60mg. Azole antifungals were prohibited in cycle 1 but allowed from cycle 2 with VEN dose modification. Endpoints (safety run-in): Primary: occurrence of dose-limiting toxicities (DLT) during cycle 1 and determination of recommended phase 2 doses (RP2D) using a Bayesian Logistic Regression Model. Secondary: Preliminary response rates. Molecular studies: Next generation sequencing using a custom 48-gene Roche KAPA HyperCapture myeloid panel and FLT3-ITD targeted amplicon sequencing were performed on baseline bone marrow samples. First patient enrolled: 7SEP2020. Data cut-off: 29JUN2021. Results: 32 patients were enrolled: 18 in NON-ADV and 14 in ADV strata, respectively. Two patients in the NON-ADV stratum withdrew within the first 7 days due to non-therapy related reasons (1=personal, 1=incidental lung lesion) and were not DLT/response evaluable. Median age was 77 years (68-87; 69% ≥75 years). 43.8% (14/32) had secondary/therapy related AML. Although gastrointestinal adverse events (AE) during cycle 1 were more common in VEN-LDAC-PRAN arm with nausea (57 vs 17%), vomiting (36% vs 6%) and diarrhea (50% vs 22%), grade 3+ toxicities were uncommon (0-7%)(Table 2). Occurrence of febrile neutropenia was similar between the two arms. 30-day mortality was 0% and 14% (2/14: 1=infection, 1=disease progression) for NON-ADV and ADV strata, respectively. No DLTs were observed in either stratum across all dose levels, thus the RP2D was the highest dose level explored for both triplet combinations. The intention-to-treat overall response rate CR+CRi+CRh was 72.2% (13/18) in the NON-ADV arm and 57.1% (8/14) in ADV arm. The expanded response rate including PR and MLFS was 77.8% (14/18) and 71.4% (10/14) in the NON-ADV and ADV strata, respectively. Median time to best response was 1 cycle (range 1-6). Updated response and survival outcomes will be presented at the meeting. Conclusion: The addition of MIDO or PRAN to VEN-LDAC was tolerable in older/unfit patients with treatment naïve AML. Preliminary efficacy with this risk-stratified approach compared favorably to prior studies with VEN-LDAC alone (Wei et al Blood 2020: CR+CRi 56% in NON-ADV, 28% in ADV). The randomized phase 2 part of this tandem triplet strategy with the goal of preventing adaptive resistance is underway. Figure 1 Figure 1. Disclosures Chua: Abbvie: Other: Conference travel and accommodation . Reynolds: Alcon: Current equity holder in publicly-traded company; Abbvie: Research Funding; Novartis AG: Current equity holder in publicly-traded company. Enjeti: Astra Zeneca: Honoraria; Sanofi: Honoraria; AbbVie: Honoraria; Roche: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hiwase: AbbVie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Marlton: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Queensland Health: Current Employment; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bajel: Abbvie, Amgen, Novartis, Pfizer: Honoraria; Amgen: Speakers Bureau. Grove: Astellas: Consultancy, 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. Cooney: Amgen: Other: Travel, accommodation, expenses ; Roche: Other: Travel, accommodation, expenses ; Novartis: Other: Online conference registration . Beligaswatte: Astellas: Membership on an entity's Board of Directors or advisory committees. Anstee: Walter and Eliza Hall Institute: Patents & Royalties: Dr Anstee was a former employee of the Walter and Eliza Hall Institute and is eligible for a fraction of the royalty stream related to Venetoclax. Perera: Abbvie: Speakers Bureau; BMS: Speakers Bureau. Ritchie: Takeda: Research Funding; BMS: Research Funding; Novartis: Honoraria; CRISPR Therapeutics: Research Funding; Amgen Inc: Honoraria, Research Funding; CSL: Honoraria. Wei: Genentech: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees; Macrogenics: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. OffLabel Disclosure: This presentation will focus on the ALLG INTERVENE clinical trial combining venetoclax+LDAC+midostaurin or venetoclax+LDAC+pracinostat. Although venetoclax and midostaurin are individually FDA-approved in some indications, the combinations examined in this clinical trial have not been approved by FDA.

Background: Pts with higher-risk MDS and AML need treatment options that provide durable responses with sustained clinical benefit and favorable safety/tolerability. Sabatolimab is a novel immuno-myeloid therapy targeting TIM-3, an immune regulator expressed on immune cells and myeloid leukemic progenitors but not on normal hematopoietic stem cells. Sabatolimab + HMA has been shown to deliver promising durable responses in a phase (Ph) Ib study in pts with vHR/HR-MDS or newly diagnosed (ND) AML (Wei et al. EHA 2021; NCT03066648). We report updated data from this study, including new analyses evaluating a potential relationship between immune-mediated effects of sabatolimab and response. Final results with additional follow-up will be reported at the time of presentation. Methods: Eligibility criteria and design of this multicenter, open-label study have been previously reported (Wei et al. EHA 2021). The primary objective was to evaluate safety and tolerability. Preliminary efficacy, a key secondary objective, was assessed with overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS) endpoints. Safety and preliminary efficacy are reported for sabatolimab + HMA in pts with vHR/HR-MDS (per IPSS-R) or ND-AML. The proportion of pts who had a possible immune-mediated adverse event (imAE) was evaluated among pts who achieved remission (CR + PR + CRi/mCR) compared with pts that have not achieved remission. The outcomes of pts who received hematopoietic stem cell transplantation (HSCT) after coming off the study were assessed independent of the study by investigators. Results: As of the 15 Jun 2021 data cutoff, 53 pts with vHR/HR-MDS and 48 with ND-AML were treated with sabatolimab + HMA. The combination was safe and well tolerated, with the most common (≥15% in either vHR/HR-MDS or ND-AML) gr ≥3 AEs similar to HMA alone, consisting of thrombocytopenia (43.4%, 45.8%), neutropenia (47.2%, 50.0%), anemia (28.3%, 33.3%), and febrile neutropenia (35.8%, 29.2%), respectively. No pt with vHR/HR-MDS and only 3 with ND-AML discontinued treatment due to an AE regardless of relationship to treatment. In vHR/HR-MDS, 24.5% of pts had improvement allowing them to undergo HSCT. While on study, 6 pts with vHR/HR-MDS and 10 with ND-AML had possible imAEs regardless of relationship to study treatment. Few pts had clinically significant possible imAEs, with no gr ≥3 possible imAEs in pts with vHR/HR-MDS. In ND-AML, 5 pts had gr 3 and none had gr 4/5 possible imAEs. Among 51 pts with vHR/HR-MDS evaluable for response, ORR was 56.9%, with a median DOR (mDOR) of 16.1 mo (Table). The mDOR in pts with CR was 21.5 mo (95% CI, 12.1-NE). Estimated 12-mo PFS rate was 51.9% (95% CI, 30.6%-69.6%). In 40 evaluable pts with ND-AML, ORR was 40.0% and mDOR was 12.6 mo. The mDOR in pts with CR was 23.0 mo (95% CI, 1.3-NE). Estimated 12-mo PFS rate was 27.9% (95% CI, 14.9%-42.5%). Durable responses were also observed in pts with adverse-risk mutations, including TP53 mutations in pts with vHR/HR-MDS (ORR: 71.4% [10/14]; mDOR 21.5 mo [95%CI, 6.7-NE]) and at least 1 ELN adverse-risk mutation (TP53/RUNX1/ASXL1) in pts with ND-AML (ORR: 53.8% [7/13]; mDOR 12.6 mo [95%CI, 1.3-NE]). Although the majority (75%) of pts who went into remission did not experience an imAE, pts in the vHR/HR-MDS cohort who achieved remission more often had a possible imAE (6/24 [25%]) than pts without remission (n=27), none of whom had an imAE. Notably, all 6 pts with vHR/HR-MDS who had an imAE achieved remission. Among pts with ND-AML, the frequency of possible imAEs was similar regardless of remission status. Of the subset of pts who proceeded to HSCT, post-HSCT outcomes in pts with vHR/HR-MDS treated with sabatolimab + HMA were generally favorable without excess toxicities related to graft-versus-host disease. Conclusions: Sabatolimab + HMA was safe and well tolerated and demonstrated durable clinical responses in pts with vHR/HR-MDS and ND-AML. Responses were also durable in pts with adverse-risk mutations. The observed relationship between response and possible imAEs in vHR/HR-MDS would need further confirmation in ongoing studies, but suggests that an immunomodulatory mechanism of sabatolimab may be contributing to clinical responses. The STIMULUS clinical trial program is evaluating sabatolimab-based combination therapy in multiple Ph II and III studies in MDS and AML. Co-senior authors Uma Borate and Andrew H. Wei contributed equally. Figure 1 Figure 1. Disclosures Brunner: Celgene, Forty Seven Inc, Jazz: Other: Advisory Board; Novartis, Celgene, Takeda, AstraZeneca: Research Funding. Esteve: Bristol Myers Squibb/Celgene: Consultancy; Abbvie: Consultancy; Novartis: Consultancy, Research Funding; Astellas: Consultancy; Jazz: Consultancy; Pfizer: Consultancy; Novartis: Research Funding. Knapper: Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Astellas: Consultancy, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau. Traer: Schrodinger: Research Funding; ImmunoGen: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Servier/Agios: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees. Vey: Amgen: Honoraria; BMS: Honoraria; BIOKINESIS: Consultancy, Research Funding; NOVARTIS: Consultancy, Honoraria, Research Funding; SERVIER: Consultancy; JAZZ PHARMACEUTICALS: Honoraria; JANSSEN: Consultancy. Wermke: Novartis, Roche, Pfizer, BMS: Consultancy, Honoraria, Research Funding. Janssen: Uppsala County Council: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding; Roche: Speakers Bureau; Avillion: Research Funding; Ellipses Pharma: Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy; Incyte Biosciences Benelux BV: Research Funding, Speakers Bureau; Glycomimetics: Research Funding. Narayan: Novartis: Research Funding; Sanofi Genzyme: Other: Spouse employment & equity interest; Takeda: Other: Spouse employment & equity interest; Genentech: Other: Spouse employment & equity interest. Kontro: Jazz Pharmaceuticals: 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: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ottmann: Celgene/BMS: Honoraria, Research Funding; Fusion: Honoraria; Novartis: Honoraria; Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding. Naidu: Novartis: Current Employment. Pelletier: Novartis: Current Employment. Han: Novartis: Current Employment, Current equity holder in publicly-traded company. Lewandowski: Novartis Institutes: Current Employment. Zhang: Novartis Institutes for BioMedical Research: Current Employment. Mohammed: Novartis: Current Employment. Rinne: Novartis: Current Employment; Qiagen: Consultancy. Borate: Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; incyte: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rampal: Membership on an entity's Board of Directors or advisory committees; Galecto, Inc.: Consultancy; Promedior: Consultancy. Wei: Novartis, Janssen, Amgen, Roche, Pfizer, Abbvie, Servier, BMS, Macrogenics, Agios, Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis, Celgene, AbbVie, Servier, AstraZeneca, and Amgen: Research Funding; Astellas: Honoraria. OffLabel Disclosure: Sabatolimab is a novel immuno-myeloid therapy targeting TIM-3 and is under investigation for the treatment of patients with myeloid malignancies