Walter, Roland B

Abstract Introduction: While newly diagnosed patients (pts) with acute myeloid leukemia (AML) who are ineligible for intensive chemotherapy have prolonged survival outcomes with venetoclax plus azacitidine (VEN+AZA) over AZA alone (2-year overall survival rate: 37.5% vs 16.9%), more can be done to further enhance outcomes (Pratz et al., 2024). CD123 is overexpressed on AML blasts and leukemia stem cells in AML. Pivekimab sunirine (PVEK) is a first-in-class antibody-drug conjugate comprised of a high-affinity anti-CD123 antibody, a cleavable linker, and an indolinobenzodiazepine pseudodimer payload. Previously, in pts with CD123-positive AML, PVEK combined with VEN+AZA demonstrated robust response rates with a manageable safety profile (Daver et al., 2023). Here we report a subgroup analysis from a preliminary cohort of frontline (1L)-treated pts with AML. Methods: Data are from the dose expansion phase of an ongoing, open-label, multicenter, fully enrolled, Phase 1b/2 study of PVEK+VEN+AZA in adults with 1L unfit AML deemed CD123-positive by investigator. Unfit pts were aged ≥75 years (yr), or aged <75 yr with Eastern Cooperative Oncology Group performance status (ECOG PS) score 2–3, or ≥1 defined comorbidity. Pts received PVEK (0.045 mg/kg, intravenous [IV]) on Day (D) 7 plus VEN (400 mg equivalent, oral) daily in a 28-D cycle (cohort 1 received ≥14 D of VEN; cohort 2 received 28 D of VEN) plus AZA (up to 75 mg/m2, subcutaneous or IV) on D1–7. Bone marrow assessments were performed by D12–14 (cohort 1) or D18–21 (cohort 2) to determine VEN duration in cycle 1 and at the end of every subsequent cycle to assess responses and myelosuppression. The primary endpoint was antileukemia activity (complete remission [CR] rate) and measurable residual disease (MRD) assessments. Responses were determined using the modified European LeukemiaNet 2017 criteria (plus CR + partial hematologic recovery [CRh]). MRD-negativity was defined centrally as <0.1% using multiparameter flow cytometry. Safety was assessed as a secondary endpoint. Results: Among 1L unfit pts with CD123-positive AML (n=49), the median (range) age was 77 (58–85) yr, with most pts aged ≥75 yr (n=36 [74%]). Forty-two (86%) pts reported an ECOG PS ≤1, 14% (n=7) had secondary AML, and 20% (n=10) and 51% (n=25) had intermediate or adverse cytogenetic risk, respectively; 65% (n=32) and 35% (n=17) were reported as TP53wt or TP53mut, respectively. Eight (16%) pts bridged to stem cell transplant. The median (range) number of treatment cycles and duration of treatment were 4 (1–20) and 5.5 (0.7–22.7) months (mo), respectively, for PVEK; 4 (1–20) and 5.1 (0.9–22.9) mo for VEN; and 4 (1–21) and 5.7 (0.9–23.4) mo for AZA. For cohort 1 (n=10), the median (range) duration of VEN was 4.5 (2.1–22.9) mo, and for cohort 2 (n=39), the median (range) duration of VEN was 5.7 (0.9–15.2) mo. With a median (range) follow-up of 10 (1.2–26.7) mo, 63.3% (95% CI: 48.3%–76.6%) of pts achieved CR, 79.6% (95% CI: 65.7%–89.8%) achieved CR/CR with incomplete hematologic recovery (CRi), and 73.5% (95% CI: 58.9%–85.1%) achieved CR/CRh; morphologic leukemia free state was achieved in 4% (n=2) of pts. Of pts who achieved CR or CR/CRi with a MRD-evaluable sample, 92% (23/25) and 90% (27/30) achieved flow cytometry MRD-negativity (<0.1%) respectively. The most common (≥50% of pts) any grade treatment-emergent adverse events (AEs) were neutropenia/neutrophil count decreased and thrombocytopenia/platelet count decreased (both 69%); constipation (61%); and peripheral edema (51%). Three pts (6%) experienced AEs leading to discontinuation (myocardial infarction/soft tissue infection/thrombocytopenia) and 2 pts had AEs leading to death (respiratory failure/pancytopenia). Conclusions: Unfit pts with newly diagnosed CD123-postive AML demonstrated high CR rates with PVEK+VEN+AZA. These robust response rates were observed across the select mutational profiles tested. Follow up with duration of response and survival estimates among all pts, by molecular subgroups and MRD negativity status, are being evaluated. Triplet therapy in unfit 1L pts with CD-123–positive AML was well-tolerated, and no new safety signals were observed. These data highlight the need to further evaluate this regimen in a randomized trial.

PURPOSE Ziftomenib—a potent, highly selective, oral menin inhibitor—was well tolerated and demonstrated encouraging clinical activity as monotherapy for relapsed/refractory NPM1 -mutated ( NPM1 -m) and KMT2A -rearranged AML in the KOMET-001 phase I trial. METHODS In the registration-enabling phase II part of KOMET-001, patients with relapsed/refractory NPM1 -m AML received ziftomenib 600 mg once daily. The primary end point was the rate of complete remission with full hematologic recovery (CR)/CR with partial hematologic recovery (CRh). RESULTS From January 26, 2023, to May 13, 2024, 92 patients (median age, 69 years [range, 33-84]) were treated. The primary end point was met, with a CR/CRh rate of 22% (95% CI, 14 to 32; P = .0058); 61% were negative for measurable residual disease. Overall response rate was 33% (95% CI, 23 to 43), with a median duration of 4.6 months (95% CI, 2.8 to 7.4). Prespecified subgroup analyses showed comparable CR/CRh regardless of previous therapy, including venetoclax, or type of comutations. Median overall survival was 6.6 months (95% CI, 3.6 to 8.6). Common grade ≥3 treatment-emergent adverse events were febrile neutropenia (26%), anemia (20%), and thrombocytopenia (20%). Differentiation syndrome occurred in 25% of patients (15% grade 3; no grade 4-5) and was manageable with protocol-defined mitigation. Three patients (3%) discontinued treatment because of ziftomenib-related adverse events. CONCLUSION Ziftomenib demonstrated significant clinical benefit and deep responses in patients with heavily pretreated, relapsed/refractory NPM1 -m AML. Ziftomenib was well tolerated with a safety profile consistent with previous studies, including manageable differentiation syndrome, lack of clinically significant QTc prolongation, and low rates of myelosuppression.

Background In unfit patients (pts) with newly diagnosed (ND) AML, long-term survival remains short (mOS 14.7 months) despite improved responses (CR 37% and CR/CRi 66%) with azacitidine (AZA) and venetoclax (VEN) (VIALE-A, DiNardo NEJM 2020). In a pooled analysis of AZA-VEN in ND AML pts with poor risk cytogenetics the response rates were higher in TP53wt pts (CR/CRi 70%) compared with TP53mut pts (CR/CRi 41%) (Pollyea Clin Cancer Res 2022). The measurable residual disease (MRD)-negative rate was 41% in AZA-VEN treated pts in VIALE-A which was associated with improved survival (Pratz JCO 2022). Pivekimab sunirine (PVEK, IMGN632) is a first-in-class antibody-drug conjugate (ADC) comprising a high-affinity CD123 antibody, cleavable linker, and an indolinobenzodiazepine pseudodimer (IGN) payload. The novel IGN payload alkylates DNA and causes single strand breaks without crosslinking (Kovtun Blood Adv 2018). Methods This is an ongoing, open-label, multicenter, Phase 1b/2 study of PVEK in combination with AZA +VEN in adults with ND CD123-positive AML (any CD123+ expression by local flow cytometry or IHC). Pts received the recommended phase 2 dose of PVEK 0.045 mg/kg IV on D7 + AZA 75 mg/m 2 SC or IV daily on D1-7 + VEN up to 400 mg PO daily for 14 to 28 days (based on cohort assignment) in a 28-day cycle. Bone marrow assessment was performed at D14 (cohort 1) or D21 (cohort 2) of cycle 1 to determine VEN duration. The primary endpoints are composite CR rate (CCR [CR+CRh+CRp+CRi]), MRD rate (assessed centrally [Hematologics, Inc.] by flow cytometry; <0.1% defined as negative) and duration of remission. Key secondary endpoints are safety, pharmacokinetics and immunogenicity. Responses were determined using ELN 2017 criteria (with the addition of CRh) and a 14-day post-marrow count recovery window. Results As of July 17, 2023, data is available for 50 ND pts (n=25 per cohort) treated with PVEK+AZA+VEN and are aggregately reported here. The median age was 74 years (range, 46-83), 42% were ≥ 75 years old, 26% had secondary AML, 64% were ELN 2017 adverse risk, and 38% had a TP53mut. The most common non-hematologic treatment-emergent adverse events (TEAE) (all grades [grade 3+]) seen in > 20% of all pts were febrile neutropenia (44% [38%]), constipation (42% [2%]), peripheral edema (36% [4%]), diarrhea (36% [2%]), hypophosphatemia (32% [0%], nausea (28% [4%]), and hypokalemia (24% [2%]). No veno-occlusive disease (VOD) events were reported. In responders, the median time to achieve absolute neutrophil count ≥500/µL and platelet count ≥50,000/µL was 35.5 days (range, 20-55) and 22 days (range, 20-55), respectively. The median post-remission cycle delay (beyond cycle day 28) was 14 days. Two pts discontinued PVEK due to a TEAE (edema; marrow aplasia). The 60-day mortality was 4%. In the ITT population (N=50) the CR rate was 52% (26/50), and the CCR rate was 66% (33/50). In pts ≥ 75 years old, the CCR rate was 76% (16/21). In pts known to be TP53wt, both the CR and CCR rate was 88% (22/25). Additional response subsets in Table 1. Twenty-one pts received 9-14 days of VEN, 9 pts received 15-21 days of VEN and 20 pts received ≥ 22 days of VEN in cycle 1; of those who received ≤ 14 days of VEN the CR rate was 71% (15/21) and the CCR rate was 76% (16/21). Of the 26 pts who achieved CCR and had an MRD-evaluable sample, 73% (19/26) achieved MRD negativity (CCR MRD-, <0.1% residual blasts); notably all had undetectable MRD levels (lower level of detection is 0.02%). MRD-negativity was achieved rapidly with a median of 1.7 months (range, 0.8-4.5). CCR MRD- rates were high across major molecular subsets, including FLT3 (ITD/TKD) at 100% (7/7), IDH1/2 at 89% (8/9), and NPM1 at 89% (8/9), as well as ELN risk groups (intermediate 80% [8/10]; adverse 64% [9/14]). Conclusion With a manageable safety profile in pts with ND AML, the PVEK+AZA+VEN triplet demonstrated anti-leukemia activity with robust CR rates and early MRD negative responses in a cohort enriched for adverse disease characteristics (64% ELN adverse risk; 38% TP53mut). Encouraging CCR MRD- rates were observed across cytogenetic/molecular subsets, and the majority of responding pts achieved early and deep remissions, which may translate to improved clinical outcomes. The regimen was well tolerated with no new safety signals, and the addition of PVEK to the AZA-VEN backbone did not appear to meaningfully prolong count recovery.

Abstract Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with historically poor outcomes and no worldwide consensus treatment approach. Unique among most hematologic malignancies for its frequent cutaneous involvement, BPDCN can also invade other extramedullary compartments, including the central nervous system. Generally affecting older adults, many patients are unfit to receive intensive chemotherapy, and although hematopoietic stem cell transplantation is preferred for younger, fit individuals, not all are eligible. One recent therapeutic breakthrough is that all BPDCNs express CD123 (IL3Rα) and that this accessible surface marker can be pharmacologically targeted. The first-in-class agent for BPDCN, tagraxofusp, which targets CD123, was approved in December 2018 in the United States for patients with BPDCN aged ≥2 years. Despite favorable response rates in the frontline setting, many patients still relapse in the setting of monotherapy, and outcomes in patients with relapsed/refractory BPDCN remain dismal. Therefore, novel approaches targeting both CD123 and other targets are actively being investigated. To begin to formally address the state of the field, we formed a new collaborative initiative, the North American BPDCN Consortium (NABC). This group of experts, which includes a multidisciplinary panel of hematologists/oncologists, hematopoietic stem cell transplant physicians, pathologists, dermatologists, and pediatric oncologists, was tasked with defining the current standard of care in the field and identifying the most important research questions and future directions in BPDCN. The position findings of the NABC’s inaugural meetings are presented herein.

Abstract Introduction: The interleukin-3 receptor alpha chain (CD123) is a cell-surface target aberrantly expressed on various myeloid neoplasms including blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML), and myelofibrosis (MF). Tagraxofusp (TAG, SL-401), a first-in-class CD123-targeted therapy, is the only treatment approved by the FDA and EMA for patients (pts) with BPDCN. It has also been investigated in phase 1/2 clinical trials for AML (including pts with minimal residual disease [MRD]), CMML, and MF. We report the aggregated safety data of TAG monotherapy from trials in BPDCN, AML, CMML, and MF. Methods: An integrated safety analysis was performed for pts who received TAG monotherapy in three phase 1/2, multicenter clinical studies: Study 0114 (NCT02113982; BPDCN/AML), Study 0214 (NCT02270463; AML with/without MRD), and Study 0314 (NCT02268253; CMML/MF; Table 1). Pts received the recommended phase 2 dose of 12 mcg/kg/day (d) IV on d1-3 (MF and CMML) or d1-5 (BPDCN and AML) and were analyzed for incidence and timing of treatment-related adverse events (TRAEs), AEs of interest, and discontinuations. Safety data for TAG monotherapy, reported as individual case study reports (ICSRs) postapproval (US) and from an early access program (EAP; EU) are also presented. Results: In total, 201 pts receiving TAG (12 mcg/kg/d) in a clinical trial setting were included: BPDCN, n=86; AML, n=36; AML with/without MRD, n=10; CMML, n=33; MF, n=36. As of Jul 2021, 11 (6%) pts discontinued TAG due to any-grade (Gr) TRAE. Most common TRAEs (any-Gr) are shown in Table 2 and included hypoalbuminemia (41%), increased alanine aminotransferase (ALT; 40%), increased aspartate aminotransferase (AST; 39%), and thrombocytopenia (26%). The most common Gr ≥3 TRAEs were thrombocytopenia (n=41; 20%), increased AST (n=40; 20%), and increased ALT (n=35; 17%). Tumor lysis syndrome occurred in 5% of pts and 1.5% had infusion-related reactions. Any-Gr and Gr ≥3 hematologic TRAEs are presented in Table 3. Most common was thrombocytopenia. All TRAEs were transient in nature; prolonged bone marrow suppression was not observed. Overall, 23% (47/201) of pts experienced ≥1 treatment-related serious AE. Onset of most TRAEs, irrespective of Gr, commonly occurred in cycle 1 and resolved by cycle 2. Although the number of pts in cycles ≥2 was lower than in cycle 1, the incidence rates of common TRAEs also substantially decreased in subsequent cycles. Capillary leak syndrome (CLS) occurred in 17% of the overall 201 pts. The majority of all CLS events were nonsevere, Gr ≤2 (n=22; 63%); also reported were Gr 3, n=10 (29%); Gr 4, n=3 (9%), and 2 pts experienced a Gr 5 event. Onset of CLS was usually within the first week of cycle 1 (median time to onset [range], d: 5.5 [1-51]) and resolved quickly (median time to resolution [range], d: 5.0 [2-69]); no pts experienced the first onset after cycle 2. Of the 15 pts who resumed treatment after an initial CLS event, only 1 pt experienced a recurrence. The most common AEs reported as ICSRs postapproval and from an EAP (December 2018 to June 2021) were CLS, blood albumin decreased, thrombocytopenia, pyrexia, and hepatic enzyme increased. No new safety signals that would alter the safety profile were observed. Conclusions: This integrated analysis represents the largest collection of safety data (N=201) following treatment with TAG monotherapy. TAG has an established and manageable safety profile, with the vast majority of AEs reported as transient and decreasing in frequency/severity with increasing cycles. CLS was reported in 17% of pts; onset was usually within cycle 1, resolved quickly (median time to resolution: 5.0 d) by early intervention measures including holding treatment, and no pts experienced first onset after cycle 2. Risk-minimization guidelines for CLS were developed and implemented during clinical trials and incorporated into prescribing information. No myelosuppression or cumulative toxicity was observed over multiple treatment cycles. The safety profile observed postapproval and in the EAP was consistent with the clinical trial data reported, reflecting successful adoption of risk-management strategies in real-world practice. These data confirm the favorable benefit-risk profile of TAG monotherapy has been maintained in the 3 years following US approval. Figure 1 Figure 1. Disclosures Pemmaraju: ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Sager Strong Foundation: Other; Blueprint Medicines: Consultancy; Incyte: Consultancy; Bristol-Myers Squibb Co.: Consultancy; Pacylex Pharmaceuticals: Consultancy; Cellectis S.A. ADR: Other, Research Funding; Aptitude Health: Consultancy; Celgene Corporation: Consultancy; CareDx, Inc.: Consultancy; Springer Science + Business Media: Other; Daiichi Sankyo, Inc.: Other, Research Funding; Samus: Other, Research Funding; Clearview Healthcare Partners: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; MustangBio: Consultancy, Other; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; LFB Biotechnologies: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Affymetrix: Consultancy, Research Funding; DAVA Oncology: Consultancy; Plexxicon: Other, Research Funding; Roche Diagnostics: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; ImmunoGen, Inc: Consultancy. Kantarjian: NOVA Research: Honoraria; Aptitude Health: Honoraria; Immunogen: Research Funding; BMS: Research Funding; Precision Biosciences: Honoraria; Novartis: Honoraria, Research Funding; Ascentage: Research Funding; Pfizer: Honoraria, Research Funding; Astra Zeneca: Honoraria; Astellas Health: Honoraria; Jazz: Research Funding; Ipsen Pharmaceuticals: Honoraria; Amgen: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; KAHR Medical Ltd: Honoraria; AbbVie: Honoraria, Research Funding; Taiho Pharmaceutical Canada: Honoraria. Sweet: Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Wang: Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; DAVA Oncology: Consultancy, Speakers Bureau; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Genentech: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Takeda: Consultancy, Honoraria, Other: Advisory board; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Rafael Pharmaceuticals: Other: Data safety monitoring committee; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Lane: N-of-One: Consultancy, Honoraria; Stemline Therapeutics: Research Funding; Qiagen: Consultancy, Honoraria; AbbVie: Research Funding. Ali: Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees. Stein: Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau; Stemline: Speakers Bureau. Yacoub: Agios: Membership on an entity's Board of Directors or advisory committees; Acceleron Pharma: Membership on an entity's Board of Directors or advisory committees; CTI Biopharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau. Rizzieri: Celltron/Teva: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: presentation to FDA for biosimilar review ; AROG: Other; Amgen: Other: personal fee; Bayer: Consultancy, Honoraria; Kite: Other: personal fee; Mustang: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Other: personal fee; Gilead: Other: personal fee; Jazz: Other: personal fee; Pharmacyclics: Other. Vasu: Seattle Genetics: Other: travel support; Boehringer Ingelheim: Other: Travel support; Kiadis, Inc.: Research Funding; Omeros, Inc.: Membership on an entity's Board of Directors or advisory committees. Gupta: AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy; Constellation Pharma: Consultancy, Honoraria; Pfizer: Consultancy; BMS-Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sierra Oncology: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Research Funding. Lee: BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pin Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Innate: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees. Schiller: Sangamo: Research Funding; Actinium Pharmaceuticals, Inc: Research Funding; FujiFilm: Research Funding; Pfizer: Current equity holder in publicly-traded company, Research Funding; Abbvie: Research Funding; Karyopharm: Research Funding; Onconova: Research Funding; Celator: Research Funding; Actuate: Research Funding; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Trovagene: Research Funding; Deciphera: Research Funding; Gamida Cell Ltd.: Research Funding; Forma: Research Funding; Ono-UK: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Arog: Research Funding; Takeda: Research Funding; Geron: Research Funding; Jazz: Consultancy, Honoraria, Research Funding, Speakers Bureau; PrECOG: Research Funding; Kite/Gilead: Honoraria, Research Funding, Speakers Bureau; Mateon: Research Funding; Constellation Pharmaceuticals: Research Funding; Daiichi-Sankyo: Research Funding; Tolero: Research Funding; Stemline Therapeutics, Inc.: Honoraria, Research Funding, Speakers Bureau; Samus: Research Funding; Astellas: Honoraria, Research Funding, Speakers Bureau; Regimmune: Research Funding; BMS/Celgene: Consultancy, Current equity holder in publicly-traded company, Research Funding, Speakers Bureau; Agios: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy, Current equity holder in publicly-traded company, Honoraria, Research Funding, Speakers Bureau; Bio: Research Funding; Elevate: Research Funding; Delta-Fly: Research Funding; Genentech-Roche: Research Funding; Ariad: Research Funding; Sanofi: Honoraria, Research Funding, Speakers Bureau; Pharma: Consultancy; Johnson & Johnson: Current equity holder in publicly-traded company; Biomed Valley Discoveries: Research Funding; Eli Lilly: Research Funding; ASH foundation: Other: Chair-unpaid; Sellas: Research Funding; Ono: Consultancy; Incyte: Consultancy; AstraZeneca: Consultancy; Kaiser Permanente: Consultancy; Cyclacel: Research Funding; MedImmune: Research Funding; Ambit: Research Funding; Leukemia & Lymphoma Society: Research Funding; Bluebird Bio: Research Funding; Boehringer-Ingleheim: Research Funding; Cellerant: Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Kura Oncology: Research Funding; Pharmacyclics: Honoraria, Speakers Bureau; Millennium: Research Funding; National Marrow Donor Program: Research Funding; NIH: Research Funding; Onyx: Research Funding; Pharmamar: Research Funding; UC Davis: Research Funding; UCSD: Research Funding; Evidera: Consultancy; NCI: Consultancy; Novartis: Speakers Bureau. Foran: trillium: Research Funding; actinium: Research Funding; aptose: Research Funding; novartis: Honoraria; OncLive: Honoraria; servier: Honoraria; gamida: Honoraria; takeda: Research Funding; boehringer ingelheim: Research Funding; abbvie: Research Funding; certara: Honoraria; bms: Honoraria; pfizer: Honoraria; sanofi aventis: Honoraria; revolution medicine: Honoraria; taiho: Honoraria; syros: Honoraria; kura: Research Funding; h3bioscience: Research Funding; aprea: Research Funding; sellas: Research Funding; stemline: Research Funding. Walter: Macrogenics: Consultancy, Research Funding; Jazz: Research Funding; Pfizer: Consultancy, Research Funding; Selvita: Research Funding; Amphivena: Consultancy, Other: ownership interests; Agios: Consultancy; Astellas: Consultancy; BMS: Consultancy; Genentech: Consultancy; Janssen: Consultancy; Kite: Consultancy; Immunogen: Research Funding; Celgene: Consultancy, Research Funding; Aptevo: Consultancy, Research Funding; Amgen: Research Funding. Sieminski: Stemline Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Patnaik: Kura Oncology: Research Funding; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics: Membership on an entity's Board of Directors or advisory committees. Mughal: Oxford University Press, Informa: Other: financial benefit and/or patents ; Stemline: Current Employment, Current holder of stock options in a privately-held company. Konopleva: Calithera: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Stemline Therapeutics: Research Funding; KisoJi: Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Cellectis: Other: grant support; Sanofi: Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding.

Background: Less-fit patients with acute myeloid leukemia (AML) or high-risk myelodysplasia (MDS) age 60 years and older constitute the majority of patients with AML/MDS but are not well represented in clinical trials. DNA-methyltransferase inhibitor (HMA) monotherapy (e.g. azacitidine or decitabine) is usual. Overall response rates (ORR) are low; improvement in overall survival relative to supportive care alone is modest, highlighting the critical need for efficient identification of effective novel therapies. Blocking programed cell death protein-1 (PD-1) signaling with nivolumab may increase the sensitivity of AML cells to azacitidine and improve outcomes and is the focus of one arm of the S1612 trial. Signaling through PD-1 contributes to tumor immune evasion and growth in AML [Chen, Cancer Biol Ther 2008]. Increased expression of PD-1 (~40% of AML), is associated with poor HMA response [Ørskov, Oncotarget 2015]. A single center azacitidine/nivolumab non-randomized phase II study in relapsed/refractory AML reported ORR of 33% (23/70), including 22% complete remission/complete remission with incomplete hematologic recovery [Daver, Cancer Discovery 2018]. About 25% of the patients developed grade 2-4 immune toxicities; nivolumab immune-related adverse events led to treatment discontinuation in nearly 1 in 7 patients. Study Design and Methods:The S1612 trial [NCT03092674] is a platform randomized phase II/III clinical trial with a common azacitidine control arm (CA) and two currently active experimental arms (EA). Therapy is intended for community setting: azacitidine/nivolumab; and azacitidine/midostaurin. The innovative design utilizes a phase II go/no-go decision comparing each EA with the CA independently when there are 100 pts/arm and 104 deaths on the EA and CA combined. EAs will proceed to phase III if the null hypothesis (HR=1) is rejected in favor of the EA (15% one-sided alpha). When the two currently active EAs complete phase II accrual, a third EA (decitabine/cytarabine) will open. The CA stays open the entire length of the trial and only concurrently randomized patients will be compared across arms. If an EA proceeds to phase III, 200 additional patients (300 total patients) will be accrued. Phase III analysis occurs 1.5 years after accrual or at 414 deaths (in the respective EA and CA), whichever comes first. The phase III tests the null hypothesis with 4.5% two-sided alpha and 83% power for each EA to detect an improvement in median OS from 10.4 to 15.6 months. Eligible pts are age ≥60 years, newly diagnosed AML with ≥ 20% blasts or myelodysplastic syndrome with excess blasts-2 (MDS-EB-2); deemed by the treating physician unfit for standard cytotoxic chemotherapy; and no prior HMA permitted. Trial in Progress Issues:Between December 2017 and October 2018, 113 patients were screened and 78 randomized to study treatment (median/range age: 75/61-86 years; median/range performance status 1/0-3). Two concerns challenged this trial: 1) required administration of 7-day azacitidine at the enrolling sites created a burden for this population and 2) an early excess grade 5 toxicity signal in the azacitidine/nivolumab arm compared with the control arm. Without a control comparison, this safety signal likely would have been missed. Strategies to address these concerns were developed by the study team. Discussion with the sponsor and US Food and Drug Administration (FDA) focused on allowance of standard-of-care protocol-directed azacitidine administration in the patient's primary care doctor's office rather than at the oncology center. Because of the toxicity concern, the trial was placed on partial clinical hold for further evaluation and possible nivolumab-arm eligibility changes, along with new surveillance and pre-emptive action including prompt steroid initiation for suspected immune-related toxicities. The S1612 trial highlights special concerns when enrolling vulnerable populations onto leukemia clinical trials, and the importance of collaborative strategies including with the FDA to preserve clinical trial integrity for patient benefit. It also demonstrates the efficiency this novel platform design has for therapeutic investigation and, importantly, very early identification of serious toxicity. Updates on accrual and resolution and of these issues will be presented. Disclosures Hay: Kite: Research Funding; Gilead: Research Funding; AbbVie: Research Funding; Janssen: Research Funding; MorphoSys: Research Funding; Seattle Genetics: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Roche: Research Funding; Novartis: Research Funding. Assouline:Janssen: Consultancy, Honoraria, Speakers Bureau; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Speakers Bureau; Abbvie: Consultancy, Honoraria. Walter:Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy; New Link Genetics: Consultancy; Agios: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Seattle Genetics: Research Funding; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Boston Biomedical: Consultancy; Covagen: Consultancy; Daiichi Sankyo: Consultancy; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; Amgen: Consultancy. Foran:Agios: Honoraria, Research Funding. Radich:TwinStrand Biosciences: Research Funding; Novartis: Other: RNA Sequencing. Othus:Celgene: Other: Data Safety and Monitoring Committee; Glycomimetics: Other: Data Safety and Monitoring Committee. Erba:Astellas Pharma: Consultancy; Amgen: Consultancy; Amgen: Consultancy; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy, Research Funding, Speakers Bureau; MacroGenics: Consultancy, Other: Lecture fees, Research Funding; Pfizer: Consultancy; Pfizer: Consultancy; ImmunoGen: Consultancy, Research Funding; Covance: Other: Fees for serving as chair on an independent review board for AbbVie Phase III studies; Astellas Pharma: Consultancy; Covance: Other: Fees for serving as chair on an independent review board for AbbVie Phase III studies; MacroGenics: Consultancy, Other: Lecture fees, Research Funding; AbbVie: Consultancy, Other: Chair, IRC for phase III studies, Research Funding; AbbVie: Consultancy, Other: Chair, IRC for phase III studies, Research Funding; Seattle Genetics: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy, Other: chair, AML Registry Scientific Steering Committee, Speakers Bureau; Celgene: Consultancy, Other: chair, AML Registry Scientific Steering Committee, Speakers Bureau; Daiichi Sankyo: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; GlycoMimetics: Consultancy, Other: Chair, data and safety monitoring board, Research Funding; GlycoMimetics: Consultancy, Other: Chair, data and safety monitoring board, Research Funding; Agios: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau. Michaelis:Pfizer: Equity Ownership, Research Funding; Incyte: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy; TG Therapeutics: Consultancy, Research Funding; JAZZ: Other: Data Safety Monitoring Board, uncompensated, Research Funding; BMS: Research Funding; Bioline: Research Funding; ASTEX: Research Funding; Janssen: Research Funding; Millenium: Research Funding; Macrogeneics: Research Funding. OffLabel Disclosure: Off label experimental combination therapies in newly diagnosed AML/MDS will be discussed, including nivolumab and azacitidine.

BACKGROUNDRAS/RAF/mitogen‐activated protein kinase activation is common in myeloid malignancies. Trametinib, a mitogen‐activated protein kinase kinase 1 (MEK1)/MEK2 inhibitor with activity against multiple myeloid cell lines at low nanomolar concentrations, was evaluated for safety and clinical activity in patients with relapsed/refractory leukemias.METHODSThis phase 1/2 study accrued patients with any relapsed/refractory leukemia in phase 1. In phase 2, this study accrued patients with relapsed/refractory acute myeloid leukemia (AML) or high‐risk myelodysplastic syndromes (MDS) with NRAS or KRAS mutations (cohort 1); patients with AML, MDS, or chronic myelomonocytic leukemia (CMML) with a RAS wild‐type mutation or an unknown mutation status (cohort 2); and patients with CMML with an NRAS or KRAS mutation (cohorts 3).RESULTSThe most commonly reported treatment‐related adverse events were diarrhea, rash, nausea, and increased alanine aminotransferase levels. The phase 2 recommended dose for Trametinib was 2 mg orally daily. The overall response rates were 20%, 3%, and 27% for cohorts 1, 2, and 3, respectively, and this indicated preferential activity among RAS‐mutated myeloid malignancies. Repeated cycles of trametinib were well tolerated with manageable or reversible toxicities; these results were similar to those of other trametinib studies.CONCLUSIONSThe selective, single‐agent activity of trametinib against RAS‐mutated myeloid malignancies validates its therapeutic potential. Combination strategies based on a better understanding of the hierarchical role of mutations and signaling in myeloid malignancies are likely to improve the response rate and duration. Cancer 2016;122:1871–9. © 2016 American Cancer Society.