Stone, Richard M.

Abstract Tyrosine kinase inhibitors (TKIs) have improved the outcomes of patients with Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL). Many older patients (pts) are not good candidates for intensive chemotherapy and are treated with TKIs plus corticosteroids or low intensity chemotherapy. Although the remission rates with this approach have been high, the median disease-free survival (DFS) has been short. Therefore, novel treatment strategies are needed. This trial evaluated the feasibility of combining the TKI dasatinib with prednisone and blinatumomab in older pts with Ph+ ALL. Methods: This trial was activated through the NCTN in January 2015 and closed to accrual in April 2021. Pt eligibility included: age ≥ 65 years; Ph+ or Ph-like ALL (with dasatinib-sensitive fusions or mutations); newly diagnosed or relapsed/ refractory; no evidence of central nervous system (CNS) disease; and adequate organ function. Treatment: For induction, pts received dasatinib 140 mg/d orally (PO) Days 1-56 along with prednisone 60 mg/m 2/d PO Days 1-24. Pts achieving complete remission (CR) or CR with incomplete count recovery (CRi) (Day 28 or Day 56) continued dasatinib until Day 84 followed by 3 cycles of post-remission therapy (PRT) with blinatumomab/ dasatinib. Pts not achieving CR or CRi by Day 56 received re-induction with blinatumomab. Response was assessed at Day 35 of blinatumomab. Pts not achieving CR/ CRi could receive a second cycle of blinatumomab. This was followed by 3 cycles of PRT with blinatumomab/ dasatinib. Maintenance therapy consisted of prednisone 60 mg/m 2/d x 5 days every 28 days for a total of 18 cycles along with dasatinib 140 mg po qd indefinitely. CNS prophylaxis included intrathecal (IT) methotrexate every 4-6 weeks x 8 doses. IT methotrexate was given at least 2 days apart from blinatumomab. Response was assessed at Days 28, 56, 84 and additional time points were dependent on response. Minimal residual disease (MRD) was assessed centrally by multi-color flow cytometry at Day 28. Statistics: 9 eligible/ evaluable pts receiving PRT were to be evaluated before enrolling additional pts. Dose-limiting toxicities (DLTs) were defined as: > Grade 3 non-hematologic toxicities with the exception of nausea, vomiting, or diarrhea (if manageable with supportive care measures) or Grade 4 neutropenia lasting > 42 days with possible relationship to dasatinib or blinatumomab. If due to unexpected accrual, 12 pts were evaluable for DLT, the following rules would apply. If > 4 of the 12 pts experienced a DLT, the study would be temporarily closed pending review. Upon re-opening, 8 additional eligible and evaluable pts would be enrolled for a total of 20 pts receiving blinatumomab. Results: Due to rapid accrual, 16 pts enrolled before accrual was paused to assess feasibility and safety. Twelve pts were evaluable for DLT and 4 experienced a DLT: Grade 3 dyspnea and gastrointestinal pain (n=1), Grade 3 hypertension (n=1), Grade 3 dyspnea (n=1), Grade 3 hyperglycemia (n=1). These adverse events were deemed acceptable by the NCI and FDA and the study re-opened. A total of 25 eligible pts were accrued. The median age was 73 years (range 62-87). All pts were newly diagnosed. One pt was Ph-like, with the remainder being Ph+; 89% of Ph+ pts had additional cytogenetic abnormalities. During induction, 2 pts experienced treatment-related non-hematologic Grade 4 toxicities. No Grade 4 or higher treatment-related non-hematologic toxicities occurred during post-remission therapy or maintenance. Twenty-three out of 25 pts (92%) achieved a CR during dasatinib-based and prednisone induction therapy. Four did not receive PRT (2 due to adverse events, 1 to receive transplant, 1 because of insurance issues). Sixteen pts who achieved CR had MRD data. Five out of 16 pts (31%) were MRD negative at Day 28. One pt remains on PRT and 10 are on maintenance. The median follow up for pts who are alive is 1.7 years. The median overall survival (OS) and DFS have not been reached as of July 8, 2021. Kaplan-Meier 3-year estimates of OS and DFS are 85% (95% CI 58%-95%) and 80% (95% CI 55%-92%), respectively (Figure). Conclusions: This trial demonstrates the feasibility of combining dasatinib and blinatumomab in Ph+ ALL. In addition, with 1.7 years of follow up, outcomes are encouraging with high estimated 3-year DFS and OS. Longer follow up will be needed to determine the durability of these results. Figure 1 Figure 1. Disclosures Advani: Kite Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Research Funding; Glycomimetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunogen: Research Funding; OBI: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Moseley: BioSight Ltd: Consultancy. Wood: Pfizer, Amgen, Seattle Genetics: Honoraria; Juno, Pfizer, Amgen, Seattle Genetics: Other: Laboratory Services Agreement. Park: Intellia: Consultancy; Kura Oncology: Consultancy; BMS: Consultancy; Affyimmune: Consultancy; Curocel: Consultancy; Novartis: Consultancy; Artiva: Consultancy; PrecisionBio: Consultancy; Servier: Consultancy; Kite Pharma: Consultancy; Innate Pharma: Consultancy; Minerva: Consultancy; Autolus: Consultancy; Amgen: Consultancy. Wieduwilt: Gilead: Membership on an entity's Board of Directors or advisory committees; Reata: Current holder of stock options in a privately-held company. Jeyakumar: Jazz: Research Funding; Pfizer: Research Funding. Atallah: Abbvie: Consultancy, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Takeda: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy. Gerds: PharmaEssentia Corporation: Consultancy; CTI BioPharma: Research Funding; Sierra Oncology: Consultancy; AbbVie: Consultancy; Celgene/Bristol Myers Squibb: Consultancy; Constellation: Consultancy; Novartis: Consultancy. O'Brien: Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy; Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding. Othus: Celgene: Other: Data safety monitoring board; Merck: Consultancy; Biosight: Consultancy; Glycomimetics: Other: Data safety monitoring board; Daiichi Sankyo: Consultancy. Litzow: Jazz: Other: Advisory Board; Pluristem: Research Funding; Amgen: Research Funding; Actinium: Research Funding; Omeros: Other: Advisory Board; Astellas: Research Funding; AbbVie: Research Funding; Biosight: Other: Data monitoring committee. Stone: Actinium: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; Arog: Consultancy, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Innate: Consultancy; Janssen: Consultancy; Jazz: Consultancy; Novartis: Consultancy, Research Funding; Onconova: Consultancy; Syndax: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Macrogenics: Consultancy. Erba: 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; 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.

Abstract Background The phase 3 trial A041202 solidified the Bruton's Tyrosine Kinase (BTK) inhibitor ibrutinib as a standard of care for older patients with previously untreated CLL by showing superior progression-free survival (PFS) as compared with bendamustine plus rituximab. While ibrutinib is highly effective in previously untreated CLL, there do remain disadvantages to this therapy, specifically the low rate of complete response (CR) and therefore need for continuous administration, which increases cost and toxicity. In older patients especially, toxicities with ibrutinib are common; with median duration of ibrutinib treatment of 32 months, 17% of patients had atrial fibrillation and 29% had grade 3 or higher hypertension on the A041202 study. Thus, strategies to decrease the exposure time to ibrutinib are of interest. Venetoclax is an inhibitor of BCL2 which has shown efficacy as a single agent and in combination with monoclonal antibodies, specifically the anti-CD20 monoclonal antibody obinutuzumab for patients with previously untreated CLL. One significant advantage to venetoclax is the ability to produce CRs and minimal residual disease negative (MRD-) responses. In this study, we compare ibrutinib plus obinutuzumab (IO) to ibrutinib plus venetoclax plus obinutuzumab (IVO) with a response-dependent discontinuation. Study Design and Methods A041702 (NCT03737981) is a randomized phase 3 study led by the Alliance for Clinical Trials in Oncology that is currently enrolling through the national clinical trials network (NCTN). Eligible patients are those patients with CLL or SLL age 70 or older who are previously untreated and in need of therapy. Patients with del17p on FISH must be age 65 or older. Previous treatment of autoimmune complications with steroids or rituximab are allowed. Patients must have intermediate or high risk Rai stage, ECOG performance status 0-2, ANC ≥ 1000/mm 3 unless due to marrow involvement and plt ≥ 30,000/mm 3. CrCl must be ≥ 40 mL/min and AST/ALT ≤ 2.5x upper limit of normal. Patients with hepatitis B must have undetectable viral load, and patients must not have an intercurrent illness which is expected to limit survival to < 5 years. Warfarin and strong inhibitors or inducers of CYP3A4/5 are not permitted. Patients are initially pre-registered to the study and submit a peripheral blood sample for central FISH analysis of del(17p). Patients who are registered are randomized 1:1 to Arm 1 (IO) or Arm 2 (IVO), stratified upon Rai stage and presence of del(17p). IO consists of I daily starting cycle 1 day 1, and O dosed as standard starting cycle 1 day 1 and continuing to cycle 6 day 1. IVO consists of IO as in Arm 1, with V starting cycle 3 day 1 with standard 5-week ramp-up and continuing until cycle 14 day 28. At the end of 14 cycles, both arms undergo response evaluation with central peripheral blood and bone marrow MRD testing. Patients on IO then continue I indefinitely. Patients on IVO who are in a bone marrow MRD- CR discontinue all therapy, and those who are not continue I indefinitely. The primary objective of the study is to compare PFS between IO and IVO using the strategy of response-dependent discontinuation. There is 90% power to detect a hazard ratio for PFS of 0.55 (corresponding to 5-year PFS rates of 70% and 82.187% for IO and IVO, respectively), at a one-sided significance level of 0.025 by a log-rank test. This design requires 128 events and 431 total evaluable patients assuming uniform accrual over the course of 3 years and minimum follow-up of 5 years. The study includes two interim analyses for superiority when 50% and 75% of the expected number of events have been observed and three interim analyses for futility when 25%, 50%, and 75% of the expected number of events have been observed. Conclusions A041702 is an ongoing phase 3 clinical trial using a novel response-dependent discontinuation method. Results of this study have the potential to change the standard of care for older patients with previously untreated CLL. The study is expected to accrue until third quarter 2022, and we welcome participation from sites throughout the NCTN. Disclosures Woyach: AbbVie Inc, ArQule Inc, AstraZeneca Pharmaceuticals LP, Janssen Biotech Inc, Pharmacyclics LLC, an AbbVie Company,: Consultancy; AbbVie Inc, Loxo Oncology Inc, a wholly owned subsidiary of Eli Lilly & Company: Research Funding; Gilead Sciences Inc: Other: Data & Safety; AbbVie Inc, ArQule Inc, Janssen Biotech Inc, AstraZeneca, Beigene: Other: Advisory Committee. Ruppert: Telios Pharma: Consultancy. Hill: AstraZenica: Consultancy, Honoraria; Gentenech: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel Support, Research Funding; Karyopharm: Consultancy, Honoraria, Research Funding; Epizyme: Consultancy, Honoraria; Celgene (BMS): Consultancy, Honoraria, Research Funding; Incyte/Morphysis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Beigene: Consultancy, Honoraria, Research Funding. Ding: DTRM: Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees. Stone: Syndax: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; Janssen: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Jazz: Consultancy; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Actinium: Membership on an entity's Board of Directors or advisory committees; Onconova: Consultancy; GlaxoSmithKline: Consultancy; Innate: Consultancy; AbbVie: Consultancy; Bristol Myers Squibb: Consultancy; Arog: Consultancy, Research Funding; Astellas: Membership on an entity's Board of Directors or advisory committees; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Macrogenics: Consultancy. Byrd: Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Newave: Membership on an entity's Board of Directors or advisory committees; Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria.

Abstract Introduction: Alliance for Clinical Trials in Oncology A041202 is a NCI National Clinical Trials Network phase 3 study (NCT01886872) comparing BR (Arm 1) with ibrutinib (Arm 2) and the combination of ibrutinib plus rituximab (Arm 3) to determine whether ibrutinib-containing regimens are superior to chemoimmunotherapy (CIT) in terms of progression-free survival (PFS), and whether rituximab adds benefit to ibrutinib therapy. Initial results showed that ibrutinib-containing regimens had superior PFS to CIT, and that rituximab added to ibrutinib did not improve PFS over ibrutinib alone. Pts and Methods: Eligible pts on A041202 were those age ≥ 65 years with previously untreated, symptomatic CLL. Pts had a CrCl > 40 mL/min, bilirubin < 1.5 x ULN, and no significant life-limiting intercurrent illness or need for warfarin treatment. Pts were stratified on Rai stage, Zap-70 methylation performed centrally, and del(17)(p13.1) or del(11)(q22.3) by local interphase cytogenetics and were randomized 1:1:1 to each arm. Pts on Arm 1 who progressed could cross over to Arm 2. Here we present an updated analysis after the third planned interim analysis of Arms 2 and 3 versus Arm 1, and at the second planned interim analysis for Arms 3 vs 2. PFS and OS were estimated using the Kaplan-Meier method and corresponding hazard ratios with p-values were estimated using Cox proportional hazards models. These data encompass patient visits through April 2020 and were locked 15 February 2021. Results: Between 12/9/2013 and 5/16/2016, 547 pts were randomized (Arms 1: 183, 2: 182, and 3: 182). Baseline characteristics have previously been reported; briefly, median age was 71 years, 53% had unmethylated Zap-70, 61% were IGHV unmutated (performed in 66% of patients), 6% had del(17p) and 20% del(11q) by central FISH. Stimulated karyotype was performed centrally and revealed ≥ 3 abnormalities in 27%, and ≥ 5 in 11% of patients. With median follow-up of 55 months (mo), median PFS was 44 mo (95% CI 38-54) in Arm 1 and has not been reached in Arms 2 or 3 [Arm 2 vs 1 hazard ratio (HR): 0.36, 95% CI 0.26-0.52, p<0.0001; Arm 3 vs 1 HR 0.36, 95% CI 0.25-0.51, p<0.0001; Arms 3 vs 2 HR 0.99, 95% CI 0.66-1.48, p=0.96]. 48-month PFS estimates were 47%, 76% and 76% in Arms 1, 2, and 3 respectively (Figure 1). At this time, there are no significant differences in overall survival (OS) among arms (p=0.49). 48-month OS estimates were 84%, 85%, and 86% in Arms 1, 2, and 3, respectively (Figure 2). The benefit of ibrutinib regimens over CIT, with no additional benefit of rituximab when combined with ibrutinib, was consistent for all subgroups of patients defined by TP53 abnormalities, del(11q), complex karyotype, and IGHV (Figure 3). No significant interaction effects were observed between treatment arm and del(11q), complex karyotype, or IGHV. However, greater benefit of ibrutinib regimens over CIT was observed among patients with TP53 abnormalities than without (p<0.001). Thus in Arm 1, PFS was significantly worse for those with TP53 abnormalities vs without (HR 5.32, 95% CI 3.05-9.27, p<0.0001), but in Arms 2 and 3 combined, there was no significant difference in PFS by presence/absence of TP53 abnormalities (HR 0.99, 95% CI 0.51-1.91, p=0.98). Notable adverse events with ibrutinib include atrial fibrillation or flutter (afib) and hypertension (HTN). All grade afib was seen in 11 pts on BR (6%) and 67 pts on ibrutinib (19%). All grade HTN was seen in 95 pts on BR (54%) and 263 pts on ibrutinib (73%). Conclusions: This update of the A041202 trial continues to show that ibrutinib regimens prolong PFS over BR for older patients with treatment-naïve CLL. With longer follow-up, these benefits continue to be seen across subgroups, including those associated with higher risk disease. Strikingly, within the ibrutinib arms, there does not appear to be inferior PFS for patients with abnormalities in TP53, the highest risk feature seen in CLL, and a predictor of inferior PFS with ibrutinib in relapsed CLL. This differentiates ibrutinib (and perhaps BTKi in general) from other targeted therapy paradigms for treatment-naïve CLL. Similar to prior studies, rates of afib and HTN continue to increase with time on therapy. These data support the use of ibrutinib as initial therapy in CLL, and strengthen the rationale for use of ibrutinib for high risk disease. Support: U10CA180821, U10CA180882, U24CA196171, https://acknowledgments.alliancefound.org, Pharmacyclics, Inc Figure 1 Figure 1. Disclosures Woyach: Gilead Sciences Inc: Other: Data & Safety; AbbVie Inc, ArQule Inc, Janssen Biotech Inc, AstraZeneca, Beigene: Other: Advisory Committee; AbbVie Inc, Loxo Oncology Inc, a wholly owned subsidiary of Eli Lilly & Company: Research Funding; AbbVie Inc, ArQule Inc, AstraZeneca Pharmaceuticals LP, Janssen Biotech Inc, Pharmacyclics LLC, an AbbVie Company,: Consultancy. Ruppert: Telios Pharma: Consultancy. Ding: Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; DTRM: Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees. Bartlett: ADC Therapeutics: Consultancy, Research Funding; Roche/Genentech: Consultancy; Seagen: Consultancy, Research Funding; Autolus: Research Funding; Bristol Myers Squibb: Research Funding; Celgene: Research Funding; Forty Seven: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Kite, a Gilead Company: Research Funding; Merck: Research Funding; Millennium: Research Funding; Pharmacyclics: Research Funding. Brander: Pfizer: Consultancy, Other: Biosimilars outcomes research panel; Genentech: Consultancy, Research Funding; Verastem: Consultancy; Juno Therapeutics/Celgene/Bristol Myers Squibb: Research Funding; LOXO: Research Funding; TG Therapeutics: Consultancy, Research Funding; MEI Pharma: Research Funding; NCCN: Other: panel member; ArQule/Merck: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; DTRM: Research Funding; BeiGene: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding; ArQule: Research Funding; AbbVie: Consultancy, Other: informCLL registry steering committee, Research Funding; Novartis: Research Funding. Barr: Seattle Genetics: Consultancy; Bristol Meyers Squibb: Consultancy; AstraZeneca: Consultancy; Beigene: Consultancy; Genentech: Consultancy; Abbvie/Pharmacyclics: Consultancy; Gilead: Consultancy; Morphosys: Consultancy; TG Therapeutics: Consultancy; Janssen: Consultancy. Rogers: Pharmacyclics LLC: Consultancy; Innate Pharma: Consultancy; Genentech: Consultancy, Research Funding; AstraZeneca: Consultancy; Acerta Pharma: Consultancy; AbbVie Inc.: Consultancy, Research Funding; Janssen Pharmaceuticals, Inc: Research Funding; ovartis Pharmaceuticals Corporation: Research Funding. Parikh: Pharmacyclics, MorphoSys, Janssen, AstraZeneca, TG Therapeutics, Bristol Myers Squibb, Merck, AbbVie, and Ascentage Pharma: Research Funding; Pharmacyclics, AstraZeneca, Genentech, Gilead, GlaxoSmithKline, Verastem Oncology, and AbbVie: Membership on an entity's Board of Directors or advisory committees. Coutre: Acerta: Other: Data Safety Monitoring Committee, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Data Safety Monitoring Committee, Research Funding; AstraZeneca: 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; Pharmacyclics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Larson: Epizyme: Consultancy; Astellas: Consultancy, Research Funding; Gilead: Research Funding; CVS/Caremark: Consultancy; Takeda: Research Funding; Novartis: Research Funding; Rafael Pharmaceuticals: Research Funding; Cellectis: Research Funding. Erba: AbbVie Inc: Other: Independent review 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; AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau; 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. Litzow: Jazz: Other: Advisory Board; Pluristem: Research Funding; Actinium: Research Funding; Amgen: Research Funding; Astellas: Research Funding; AbbVie: Research Funding; Omeros: Other: Advisory Board; Biosight: Other: Data monitoring committee. Blachly: INNATE: Consultancy, Honoraria; KITE: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria. Owen: Genentech: Research Funding; Gilead: Honoraria; Janssen: Honoraria, Research Funding; AstraZeneca: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Merck: Honoraria; Servier: Honoraria; Incyte: Honoraria; Pharmacyclics: Research Funding. Abramson: Bristol-Myers Squibb Company: Consultancy, Research Funding; C4 Therapeutics: Consultancy; Morphosys: Consultancy; Kite Pharma: Consultancy; Novartis: Consultancy; EMD Serono: Consultancy; Genmab: Consultancy; Bluebird Bio: Consultancy; Kymera: Consultancy; BeiGene: Consultancy; Incyte Corporation: Consultancy; Astra-Zeneca: Consultancy; Allogene Therapeutics: Consultancy; Seagen Inc.: Research Funding; AbbVie: Consultancy; Karyopharm: Consultancy; Genentech: Consultancy. Brown: Abbvie, Acerta/Astra-Zeneca, Beigene, Bristol-Myers Squibb/Juno/Celgene, Catapult, Eli Lilly, Genentech/Roche, Janssen, MEI Pharma, Morphosys AG, Nextcea, Novartis, Pfizer, Rigel: Consultancy; Invectys: Other: Data Safety Monitoring Committee Service; Gilead, Loxo/Lilly, SecuraBio, Sun, TG Therapeutics: Research Funding. Stone: Onconova: Consultancy; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Jazz: Consultancy; Arog: Consultancy, Research Funding; Gemoab: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Consultancy; Janssen: Consultancy; Innate: Consultancy; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; AbbVie: Consultancy; Actinium: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Syros: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy; Agios: Consultancy, Research Funding; Celgene: Consultancy; Macrogenics: Consultancy. Byrd: Novartis, Trillium, Astellas, AstraZeneca, Pharmacyclics, Syndax: Consultancy, Honoraria; Vincerx Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Newave: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: The ECOG-ACRIN randomized phase 3 clinical trial E1912 established ibrutinib-rituximab (IR) as the standard of care for CLL patients <= 70 years in the frontline setting by improving the progression free (PFS) and overall survival (OS) compared to previous standard chemo-immunotherapy with fludarabine, cyclophosphamide and rituximab (FCR) (Shanafelt et al. NEJM 2019). Quality of life (QOL) was an important secondary endpoint on this trial comparing continuous (IR) vs time-limited (FCR) therapy due to the differing profile of treatment-related toxicities over the short and long-term. E1912 patient-reported outcomes (PROs) results are presented here. Methods: Patients enrolled on E1912 completed the Functional Assessment of Cancer Therapy-General (FACT-G) and Leukemia subscale at randomization (baseline), 3, 6, and 12 months post-randomization, and every 6 months for 2 years regardless of disease status. The primary outcome was the 31-item FACT-Leukemia Trial Outcome Index (FACT-Leu TOI), calculated by summing items from the FACT-G physical wellbeing (PWB), functional well-being (FWB), and leukemia subscales (score range: 0-124). The primary endpoint was defined as the difference in FACT-Leu TOI change scores from randomization to 12 months (at response evaluation) between patients treated with continuous therapy Arm A (IR) vs time-limited therapy Arm B (FCR). Mean change scores from baseline to each time point were calculated using all cases with data at baseline and the corresponding time point. Comparisons between treatment arms were performed using two-sample t tests. Linear mixed effects models were used to estimate the trajectories of PRO scores. Results: PRO data was extracted on 3/8/2021. PRO data was provided at baseline and 12 months for 233/354 (65.8%) patients on the IR arm and 118/175 (67.4%) patients on the FCR arm. At enrollment, there were no significant differences in the baseline FACT-Leu TOI scores (mean ± SE) between the two arms: IR (93.27 ± 1.03) vs FCR (92.68 ± 1.38; p=0.73). The FACT-Leu TOI score improved from baseline to 12 months in both arms (Table 1 and Figure 1). The change scores from baseline to 12 months, the primary outcome, were not significantly different between IR (7.59 ± 1.09) vs FCR (8.22 ± 1.44; p=0.73). Change in FACT-Leu TOI from baseline to 3 months was 5.77 ± 0.77 and 4.06 ± 1.18 (p=0.22); and from baseline to 6 months was 6.87 ± 0.87 and 8.01 ± 1.44 (p=0.50) in the IR and FCR arms, respectively. After the first 6 months of treatment, the improvement in FACT-Leu TOI scores was maintained in both treatment arms. There was no significant difference in total FACT-Leu TOI score in the continuous therapy (IR) vs time-limited therapy (FCR) arms over the first 36 months post registration. Analysis of FACT subscales showed PWB improved in the IR arm (0.37 ± 0.22) and declined in the FCR arm (-0.92 ± 0.39) from baseline to 3 months (p=0.004 for difference in PWB change between arms) but there was no significant difference between the two arms for change in PWB scores from baseline to 6 and 12 months. There were no significant differences between the two arms for change in FWB and FACT-Leu subscales from baseline to 3, 6 and 12 months. Conclusions: QOL improves in CLL patients age 70 and younger when treated in the frontline setting with IR or FCR. The improvement in QOL is maintained during continuous therapy with ibrutinib and there is no significant decline in QOL over time. Given the improvement in PFS and OS with IR over FCR seen in E1912, the results of this QOL analysis support the use of frontline ibrutinib in previously untreated younger CLL patients. Acknowledgement: This study was conducted by the ECOG-ACRIN Cancer Research Group (Peter J. O'Dwyer, MD and Mitchell D. Schnall, MD, PhD, Group Co-Chairs) and supported by the National Cancer Institute of the National Institutes of Health under award numbers: U10CA180794, U10CA180820, UG1CA189863, UG1CA190140, UG1CA232760, UG1CA233180, UG1CA233230, UG1CA233253, UG1CA233277, UG1CA233290, UG1CA233339, UG1CA189859, UG1CA233332. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Figure 1 Figure 1. Disclosures Kay: Oncotracker: Membership on an entity's Board of Directors or advisory committees; CytomX Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolero Pharmaceuticals: Research Funding; Acerta Pharma: Research Funding; Behring: 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; TG Therapeutics: Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Juno Therapeutics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees; Dava Oncology: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Targeted Oncology: Membership on an entity's Board of Directors or advisory committees; MEI Pharma: Research Funding; Sunesis: Research Funding; Genentech: Research Funding; Bristol Meyer Squib: Membership on an entity's Board of Directors or advisory committees, Research Funding. O'Brien: Amgen, Astellas, Celgene, GlaxoSmithKline, Janssen Oncology, Aptose Biosciences Inc., Vaniam Group LLC, AbbVie, Alexion, Verastem, Juno Therapeutics, Vida Ventures, Autolus, Johnson and Johnson, Merck, Bristol Myers Squibb, NOVA Research Company, Eli Lill: Consultancy; Kite, Regeneron, Acerta, Caribou, Gilead, Pharmacyclics, TG Therapeutics, Pfizer, Sunesis: Research Funding. Coutre: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Consultancy, Honoraria, 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; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Beigene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Data Safety Monitoring Committee, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Acerta: Other: Data Safety Monitoring Committee, Research Funding. Barr: AstraZeneca: Consultancy; Gilead: Consultancy; Janssen: Consultancy; Genentech: Consultancy; Beigene: Consultancy; Bristol Meyers Squibb: Consultancy; Seattle Genetics: Consultancy; TG Therapeutics: Consultancy; Morphosys: Consultancy; Abbvie/Pharmacyclics: Consultancy. Cashen: Secura Bio, ADC Therapeutics: Consultancy. Mato: Adaptive Biotechnologies: Consultancy, Research Funding; DTRM BioPharma: Consultancy, Research Funding; Johnson and Johnson: Consultancy, Research Funding; Acerta/AstraZeneca: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; AstraZeneca: Consultancy; BeiGene: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; MSKCC: Current Employment; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Nurix: Research Funding; Janssen: Consultancy, Research Funding; Genmab: Research Funding. Erba: 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: Other: Independent review 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; AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau. Stone: Onconova: Consultancy; AbbVie: Consultancy; Boston Pharmaceuticals: Consultancy; Bristol Myers Squibb: Consultancy; Gemoab: Membership on an entity's Board of Directors or advisory committees; Elevate Bio: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Research Funding; Jazz: Consultancy; Syros: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Research Funding; Takeda: Consultancy; BerGen Bio: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Foghorn Therapeutics: Consultancy; Innate: Consultancy; Janssen: Consultancy; GlaxoSmithKline: Consultancy; Amgen: Membership on an entity's Board of Directors or advisory committees; Arog: Consultancy, Research Funding; Actinium: Membership on an entity's Board of Directors or advisory committees; Syntrix/ACI: Membership on an entity's Board of Directors or advisory committees; Aprea: Consultancy; Celgene: Consultancy; Macrogenics: Consultancy. Litzow: Actinium: Research Funding; Amgen: Research Funding; AbbVie: Research Funding; Pluristem: Research Funding; Jazz: Other: Advisory Board; Omeros: Other: Advisory Board; Astellas: Research Funding; Biosight: Other: Data monitoring committee. Tallman: NYU Grand Rounds: Honoraria; Kura: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees; Innate Pharma: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Biosight: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees; Oncolyze: Membership on an entity's Board of Directors or advisory committees; KAHR: Membership on an entity's Board of Directors or advisory committees; Orsenix: 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: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Rafael Pharmaceuticals: Research Funding; Glycomimetics: Research Funding; Biosight: Research Funding; Orsenix: Research Funding; Abbvie: Research Funding; Mayo Clinic: Honoraria; UC DAVIS: Honoraria; Northwell Grand Rounds: Honoraria; NYU Grand Rounds: Honoraria; Danbury Hospital Tumor Board: Honoraria; Acute Leukemia Forum: Honoraria; Miami Leukemia Symposium: Honoraria; New Orleans Cancer Symposium: Honoraria; ASH: Honoraria; NCCN: Honoraria. Shanafelt: Genentech, Pharmacyclics: Research Funding. Wagner: Eli Lilly, Johnson & Johnson: Other: Spouse, previously held individual stocks;; Celgene-BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; Athenex Inc: Consultancy.

Abstract Myelofibrosis (MF) is a clonal stem cell neoplasm characterized by abnormal JAK-STAT signaling, chronic inflammation, cytopenias, and risk of transformation to acute leukemia. Despite improvements in the therapeutic options for patients with MF, allogeneic hematopoietic stem cell transplantation remains the only curative treatment. We previously demonstrated multiple immunosuppressive mechanisms in patients with MF, including increased expression of programmed cell death protein 1 (PD-1) on T cells compared with healthy controls. Therefore, we conducted a multicenter, open-label, phase 2, single-arm study of pembrolizumab in patients with Dynamic International Prognostic Scoring System category of intermediate-2 or greater primary, post-essential thrombocythemia or post-polycythemia vera myelofibrosis that were ineligible for or were previously treated with ruxolitinib. The study followed a Simon 2-stage design and enrolled a total of 10 patients, 5 of whom had JAK2V617mutation, 2 had CALR mutation, and 6 had additional mutations. Most patients were previously treated with ruxolitinib. Pembrolizumab treatment was well tolerated, but there were no objective clinical responses, so the study closed after the first stage was completed. However, immune profiling by flow cytometry, T-cell receptor sequencing, and plasma proteomics demonstrated changes in the immune milieu of patients, which suggested improved T-cell responses that can potentially favor antitumor immunity. The fact that these changes were not reflected in a clinical response strongly suggests that combination immunotherapeutic approaches rather than monotherapy may be necessary to reverse the multifactorial mechanisms of immune suppression in myeloproliferative neoplasms. This trial was registered at www.clinicaltrials.gov as #NCT03065400.

Abstract Post-remission strategies after dasatinib-corticosteroid induction in adult Philadelphia chromosome (Ph)–positive acute lymphoblastic leukemia (ALL) are not well studied. We evaluated dasatinib and dexamethasone induction then protocol-defined post-remission therapies, including hematopoietic cell transplantation (HCT). Adults (N = 65) with Ph-positive ALL received dasatinib-dexamethasone induction, methotrexate-based central nervous system (CNS) prophylaxis, reduced-intensity conditioning (RIC) allogeneic HCT, autologous HCT, or chemotherapy alone, and dasatinib-based maintenance. Key end points were disease-free survival (DFS) and overall survival (OS). The median age was 60 years (range, 22-87 years). The complete remission rate was 98.5%. With a median follow-up of 59 months, 5-year DFS and OS were 37% (median, 30 months) and 48% (median, 56 months), respectively. For patients receiving RIC allogeneic HCT, autologous HCT, or chemotherapy, 5-year DFS were 49%, 29%, and 34%, and 5-year OS were 62%, 57%, and 46%, respectively. Complete molecular response rate after CNS prophylaxis was 40%. Relative to the p190 isoform, p210 had shorter DFS (median 10 vs 34 months, P = .002) and OS (median 16 months vs not reached, P = .05). Relapse occurred in 25% of allogeneic HCT, 57% of autologous HCT, and 36% of chemotherapy patients. T315I mutation was detected in 6 of 8 marrow relapses. Dasatinib CNS concentrations were low. Dasatinib-dexamethasone followed by RIC allogeneic HCT, autologous HCT, or chemotherapy was feasible and efficacious, especially with RIC allogeneic HCT. Future studies should address the major causes of failure: T315I mutation, the p210 BCR-ABL1 isoform, and CNS relapse. This study was registered at www.clinicaltrials.gov as #NCT01256398.

Abstract E1912 was a randomized phase 3 trial comparing indefinite ibrutinib plus 6 cycles of rituximab (IR) to 6 cycles of fludarabine, cyclophosphamide, and rituximab (FCR) in untreated younger patients with CLL. We describe measurable residual disease (MRD) levels in E1912 over time and correlate them with clinical outcome. Undetectable MRD rates (<1 CLL cell per 104 leukocytes) were 29.1%, 30.3%, 23.4%, and 8.6% at 3, 12, 24, and 36 months for FCR, and significantly lower at 7.9%, 4.2%, and 3.7% at 12, 24, and 36 months for IR, respectively. Undetectable MRD at 3, 12, 24, and 36 months was associated with longer progression-free survival (PFS) in the FCR arm, with hazard ratios (MRD detectable/MRD undetectable) of 4.29 (95% confidence interval [CI], 1.89-9.71), 3.91 (95% CI, 1.39-11.03), 14.12 (95% CI, 1.78-111.73), and not estimable (no events among those with undetectable MRD), respectively. In the IR arm, patients with detectable MRD did not have significantly worse PFS compared with those in whom MRD was undetectable; however, PFS was longer in those with MRD levels <10−1 than in those with MRD levels above this threshold. Our observations provide additional support for the use of MRD as a surrogate end point for PFS in patients receiving FCR. In patients on indefinite ibrutinib-based therapy, PFS did not differ significantly by undetectable MRD status, whereas those with MRD <10−1 tended to have longer PFS, although continuation of ibrutinib would very likely be necessary to maintain treatment efficacy.

Abstract Overexpression of B-cell leukemia/lymphoma 2 (BCL2) renders acute myeloid leukemia (AML) cells resistant to chemotherapy and has been associated with unfavorable outcomes. Oblimersen (G3139) is a phosphorothioate 18-mer antisense oligonucleotide directed against the first 6 BCL2 codons. In a phase 1 study of AML patients treated with G3139, cytarabine, and daunorubicin induction with cytarabine consolidation, no antisense-related toxicity was reported, and BCL2 downregulation occurred in patients achieving complete remission. In this phase 3 trial, untreated older AML patients were randomized to cytarabine (100 mg/m2 per day on days 4-10) and daunorubicin (60 mg/m2 per day on days 4-6) followed by cytarabine consolidation (2000 mg/m2 per day on days 4-8) with (arm A) or without (arm B) G3139 (7 mg/m2 per day on days 1-10 [induction] or days 1-8 [consolidation]). A total of 506 patients were enrolled. No differences in toxicity were observed between arms. Estimated overall survival (OS) at 1 year was 43% for arm A and 40% for arm B (1-sided log rank P = .13), with no differences in disease-free (DFS; P = .26) or event-free survival (P = .80). Subgroup analyses showed patients age <70 years in arm A had improved OS by 1 month vs those in arm B (P = .04), and patients with secondary AML in arm A had better DFS vs those in arm B (P = .04). We conclude that addition of G3139 to chemotherapy failed to improve outcomes of older AML patients. However, more effective means of inhibiting BCL2 are showing promising results in combination with chemotherapy in AML. This trial was registered at www.clinicaltrials.gov as #NCT00085124.

Abstract BACKGROUND: Recurrent isocitrate dehydrogenase (IDH) 1 mutations are observed in 6-10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG-120), a potent, selective, oral, small-molecule inhibitor of the mutant IDH1 (mIDH1) protein, is a promising therapeutic candidate for the treatment of patients with mIDH1 AML. Through inhibition of mIDH1, ivosidenib suppresses the abnormal production of the oncometabolite 2-hydroxyglutarate (2-HG), leading to clinical responses via differentiation of malignant cells. AIM: To report safety and efficacy data from the first-in-human phase 1 study of ivosidenib in patients with mIDH1 advanced hematologic malignancies including relapsed/refractory (R/R) AML (NCT02074839). This is the first report of data from the 4 expansion cohorts, with a total of 258 patients treated on study. METHODS: The ongoing phase 1 study assesses the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and clinical activity of ivosidenib in mIDH1 hematologic malignancies. Enrollment was completed on May 8, 2017. During dose escalation, patients received ivosidenib as a single agent orally once daily (QD) or twice daily (BID) in 28-day cycles. The MTD was not reached and 500 mg QD was selected as the recommended dose to be tested in 4 expansion cohorts: R/R AML (Arms 1 and 4, where Arm 1 patients are those with relapse after transplantation, second or later relapse, resistance to initial induction or reinduction treatment, or relapse within 1 year of initial treatment, and Arm 4 patients have R/R AML but are not eligible for Arm 1); untreated AML (Arm 2); and other advanced hematologic malignancies including myelodysplastic syndrome (MDS) (Arm 3). Updated safety data will be presented for all patients. Efficacy outcomes will be presented for all R/R AML patients treated at 500 mg QD across the dose escalation and expansion cohorts who received their first dose of ivosidenib at least 6 months prior to the analysis cut-off date of May 12, 2017, as well as for the poorest prognosis Arm 1 subset. Efficacy data for all treated patients from the other expansion cohorts (untreated AML and other advanced hematologic malignancies including MDS) will also be presented. RESULTS: In all, 258 patients (78 in dose escalation, 180 in expansion) were treated with ivosidenib. As of May 12, 2017, 62 of 258 (24%) patients were continuing on treatment. The median duration of exposure to ivosidenib was 3.5 months (range 0.1-33.5). Twenty-two (8.5%) patients discontinued treatment to proceed to allogeneic stem cell transplantation. Treatment was well tolerated; the most common adverse events (AEs) (n=258) of any grade irrespective of causality occurring in ≥20% of patients were diarrhea (33%), leukocytosis (30%), nausea (30%), fatigue (29%), febrile neutropenia (25%), dyspnea (24%), anemia (23%), QT prolongation (23%), peripheral edema (22%), pyrexia (21%), and decreased appetite (20%). The majority of these AEs were grades 1-2 and reported as unrelated to treatment. Differentiation syndrome (DS) was observed in 29 of 258 (11.2%) patients, including grade ≥3 DS in 14 (5.4%); study drug was held owing to DS in 11 patients (4.3%), and no instances of DS led to permanent treatment discontinuation or death. The primary efficacy endpoint for R/R AML is the CR+CRh rate, i.e., the rate of complete remission (CR according to modified IWG 2003 criteria plus CR with partial hematologic recovery, defined as CR except absolute neutrophil count >0.5 × 109/L [500/µL] and platelet count >50 × 109/L [50,000/µL]). Among 125 Arm 1 R/R AML patients receiving ivosidenib 500 mg QD across dose escalation and expansion who received their first dose at least 6 months prior to the analysis cutoff date, the CR+CRh rate was 30.4% (95% CI 22.5%, 39.3%), including CR in 27 (21.6%) and CRh in 11 (8.8%) patients. Median duration of CR+CRh was 8.2 months (95% CI 5.5, 12.0), and duration of CR was 9.3 months (95% CI 5.6, 18.3). The overall response rate (CR+CRi/CRp+PR+MLFS) was 41.6% (95% CI 32.9%, 50.8%) (52/125 patients). CONCLUSION: Ivosidenib monotherapy is well tolerated in patients with mIDH1 AML and other advanced hematologic malignancies. In a high-risk, molecularly defined R/R AML patient population with unmet medical need, ivosidenib induced durable remissions and improved patient outcomes. These findings support the role of ivosidenib as an effective, oral, targeted treatment for patients with mIDH1 AML. Disclosures DiNardo: Celgene: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. De Botton: Pfizer: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Servier: Honoraria; Agios: Honoraria, Research Funding. Stein: GSK: Other: Advisory Board, Research Funding; Constellation Pharma: Research Funding; Seattle Genetics: Research Funding; Agios Pharmaceuticals, Inc.: Consultancy, Research Funding; Celgene Corporation: Consultancy, Other: Travel expenses, Research Funding; Pfizer: Consultancy, Other: Travel expenses; Novartis: Consultancy, Research Funding. Roboz: AbbVie, Agios, Amgen, Amphivena, Array Biopharma Inc., Astex, AstraZeneca, Celator, Celgene, Clovis Oncology, CTI BioPharma, Genoptix, Immune Pharmaceuticals, Janssen Pharmaceuticals, Juno, MedImmune, MEI Pharma, Novartis, Onconova, Pfizer, Roche Pharmace: Consultancy; Cellectis: Research Funding. Mims: Novartis: Honoraria. Pollyea: Takeda, Ariad, Alexion, Celgene, Pfizer, Pharmacyclics, Gilead, Jazz, Servier, Curis: Membership on an entity's Board of Directors or advisory committees; Agios, Pfizer: Research Funding. Altman: Syros: Consultancy; NCCN: Other: Educational speaker; BMS: Consultancy; Celgene: Consultancy; Astellas: Consultancy; Ceplene: Consultancy; Janssen Pharmaceuticals: Consultancy; Novartis: Consultancy; ASH: Other: Educational speaker. Collins: Celgene Corporation: Research Funding; Agios: Research Funding; Arog: Research Funding; BMS: Research Funding. Mannis: Curis: Honoraria; Juno: Research Funding; Agios: Research Funding; Amgen: Honoraria. Uy: GlycoMimetics: Consultancy; Novartis: Consultancy, Other: Travel Suppport; Boehringer Ingelheim: Consultancy. Fathi: Juno: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; Agios: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Medimmune: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Stein: Amgen: Consultancy, Speakers Bureau; Stemline: Consultancy. Erba: Celgene: Consultancy, Other: Chair, Scientific Steering Committee , Speakers Bureau; Incyte: all research support paid to University of Alabama, Consultancy, Speakers Bureau; Jazz: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Amgen: Consultancy, Other: all research support paid to University of Alabama, Research Funding; Daiichi Sankyo: Consultancy, Other: all research support paid to University of Alabama, Research Funding; ImmunoGen: Consultancy, Other: all research support paid to University of Alabama, Research Funding; MacroGen: Consultancy; Ono: Consultancy; Pfizer: Consultancy; Seattle Genetics: Consultancy, Other: all research support paid to University of Alabama, Research Funding; Sunesis: Consultancy; Millennium/Takeda: Consultancy, Other: all research support paid to University of Alabama, Research Funding; Agios: Other: all research support paid to University of Alabama, Research Funding; Juno: Other: all research support paid to University of Alabama, Research Funding; Astellas: Other: all research support paid to University of Alabama, Research Funding; Celator: Other: all research support paid to University of Alabama, Research Funding; Janssen: Other: all research support paid to University of Alabama, Research Funding; Glycomimetics: Other: Chair, Data and Safety Monitoring Committee. Traer: ImmunoGen: Consultancy; Tolero: Consultancy; Notable Labs: Equity Ownership. Stuart: Pharmacyclics LLC, an AbbVie Company: Research Funding; Amgen: Consultancy, Honoraria; Agios: Research Funding; Celator/Jazz: Research Funding; Sunesis: Consultancy, Honoraria, Other: Travel Support, Research Funding; Bayer: Research Funding; Novartis: Research Funding; Incyte: Research Funding; ONO: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Research Funding; MedImmune: Research Funding; Cantex: Research Funding; Astellas: Research Funding. Arellano: Cephalon Oncology: Research Funding. Sekeres: Celgene: Membership on an entity's Board of Directors or advisory committees. Yen: Agios: Employment, Equity Ownership. Kapsalis: Agios: Employment, Equity Ownership. Liu: Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Goldwasser: Agios: Employment, Equity Ownership. Agresta: Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Attar: Agios: Employment, Equity Ownership. Stone: Novartis: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Abbvie: Consultancy; Fuji Film: Consultancy; Jazz: Consultancy; Astellas: Consultancy; Pfizer: Consultancy; Arog: Consultancy; Ono: Consultancy; Agios: Consultancy; Sumitomo: Consultancy. Kantarjian: ARIAD: Research Funding; Bristol-Meyers Squibb: Research Funding; Delta-Fly Pharma: Research Funding; Amgen: Research Funding; Pfizer: Research Funding; Novartis: Research Funding.

Abstract Adolescents and young adults (AYAs) with acute lymphoblastic leukemia have improved outcomes when treated with pediatric-inspired regimens. CALGB 10403 was the largest prospective study to evaluate the feasibility of using a pediatric regimen in AYAs with acute lymphoblastic leukemia up to 40 years of age. This article presents the toxicity events observed in the CALGB 10403 study and compares these toxicities vs those observed among AYAs treated on the same arm of the companion Children’s Oncology Group (COG) AALL0232 study. Toxicities in CALGB 10403 were similar to those observed in COG AALL0232. Some grade 3 to 4 adverse events were more often reported in CALGB 10403 compared with COG AALL0232 (hyperglycemia, hyperbilirubinemia, transaminase elevation, and febrile neutropenia). Adverse events correlated with body mass index ≥30 kg/m2 and some with increasing age. The mortality rate in CALGB 10403 was low (4%) and similar to that in the COG AALL0232 trial. A caveat to this analysis is that only 39% of CALGB 10403 patients completed all planned protocol treatment. In COG AALL0232, although 74% of patients aged <18 years completed treatment, only 57% of patients aged ≥18 years completed treatment. This scenario suggests that issues associated with age and treating physician may be a factor. Due to its improved survival rates compared with historical controls, the CALGB 10403 regimen is now a standard of care. The hope is that the rate of protocol completion will increase as more familiarity is gained with this regimen. These trials were registered at www.clinicaltrials.gov as #NCT00558519 (CALGB 10403) and #NCT00075725 (COG AALL0232).