Kurzfassung: Background Recurrent mutations in the spliceosome complex are seen in myeloid malignancies, including acute myeloid leukemia (AML), chronic myelomonocytic leukemia (CMML), and myelodysplastic syndromes (MDS). Mutations are detected most frequently in SF3B1, SRSF2, or U2AF1, and are largely mutually exclusive. Recently, a novel SF3B1 modulator, H3B-8800, entered phase-I clinical trials. While the impact of spliceosome mutations at diagnosis and at the time of transplant has been described, there is limited data about the outcomes of patients with splicing factor-mutated disease after the initiation of standard frontline chemotherapies: induction chemotherapy (IC) or hypomethylating agents (HMA). Methods Patients with MDS, CMML, or AML with a spliceosome mutation and treated with chemotherapy were identified. Disease risk was assessed using standard criteria (IPSS-R for MDS, ELN for AML, and CPSS for CMML). Overall survival (OS) was defined as the time from start of treatment until death and censored at last known alive. Event free survival (EFS) was defined as the time from start of treatment until relapse, new therapy, or death. We identified the first therapy for newly diagnosed disease (induction chemotherapy, HMA, bone marrow transplant, or other), and grouped remissions as CR (complete remission) or CRi (complete remission with incomplete hematologic recovery). Outcomes were assessed by disease type, mutation, and initial therapy. EFS and OS were estimated by the method of Kaplan and Meier. Results We identified 88 patients diagnosed with AML, CMML, or MDS harboring a mutation in SF3B1 (n=24), SRSF2 (n=43), or U2AF1 (n=21). The median follow-up of the cohort was 637 days. The median age at diagnosis was 69.5 years (33-90), and there was no difference according to mutation (p=0.907). A diagnosis of AML was slightly more common among patients with SRSF2 mutations at the time of treatment, but this was not statistically significant (27/43, p=0.07). Patients with SF3B1 mutations were less likely to have co-mutated ASXL1 (12%, vs 42% with U2AF1 and 40% with SRSF2, p=0.0384). SRSF2 disease more often had co-mutated IDH2 (26%, vs 0% with U2AF1 and 4% with SF3B1, p=0.01). Other co-mutations did not vary significantly between U2AF1, SF3B1, or SRSF2-mutated disease (Figure 1). Patients who had a mutation in SF3B1 had a longer duration from diagnosis to first therapy (median 65 days, range 0-1159) than those with U2AF1 (median 39d) or SRSF2 (median 9d) mutations (p=0.045). A total of 31 patients received induction chemotherapy, while 50 received HMA as initial therapy; 3 patients were transplanted, and 5 received other chemotherapies (e.g. enasidenib). The remission rate for patients treated with induction was 55%, and there was no difference in rate of remission (CR+CRi) according to mutation type (U2AF1 50%, SF3B1 60%, SRSF2 53%, p=1.00). Patients treated with HMA had a remission rate of 22%, with a trend toward lower remission rates in SF3B1-mutated disease (0/11, vs. U2AF1 20% and SRSF2 33%, p=0.08). We performed a multivariate analysis for overall survival incorporating mutation type, initial treatment, disease risk group, age at the time of treatment, and disease (MDS, AML, or CMML). Compared to MDS, there was no difference in OS according to whether patients had splicing-factor mutated AML (p=0.45) or CMML (p=0.61) (Figure 2). Interestingly, although CR rates differed between all patients receiving induction or HMA, there was no difference in OS between these same groups (Figure 3, p=0.803). Conclusion In this study, there was no difference in response to frontline treatment for SF3B1-mutated myeloid malignancies compared to U2AF1- or SRSF2-mutated disease. Interestingly, there was no difference in survival according to whether patients had splicing-factor mutated AML, MDS, or CMML at the time of treatment; moreover, there was no difference in survival with induction compared to HMA therapy. Together, these point to a rationale to include AML, MDS, and CMML patients together on trials targeting these mutations, and the general need to improve on the poor outcomes with standard induction or HMA therapy. Disclosures Amrein: Takeda: Research Funding. Fathi:Celgene: Consultancy, Honoraria, Research Funding; Boston Biomedical: Consultancy, Honoraria; Jazz: Honoraria; Astellas: Honoraria; Agios: Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria; Takeda: Consultancy, Honoraria. Brunner:Novartis: Research Funding; Celgene: Consultancy, Research Funding; Takeda: Research Funding.

Kurzfassung: Patients with relapsed AML have a poor prognosis and limited responses to standard chemotherapy. Lenalidomide is an immunomodulatory drug that may modulate anti‐tumor immunity. We performed a study to evaluate the safety and tolerability of lenalidomide with mitoxantrone, etoposide and cytarabine (MEC) in relapsed/refractory AML. Adult patients with relapsed/refractory AML were eligible for this phase I dose‐escalation study. We enrolled 35 patients using a “3 + 3” design, with a 10 patient expansion cohort at the maximum tolerated dose (MTD). Lenalidomide was initially given days 1‐14 and MEC days 4‐8; due to delayed count recovery, the protocol was amended to administer lenalidomide days 1‐10. The dose of lenalidomide was then escalated starting at 5 mg/d (5‐10‐25‐50). The primary objective was tolerability and MTD determination, with secondary outcomes including overall survival (OS). The MTD of lenalidomide combined with MEC was 50 mg/d days 1‐10. Among the 35 enrolled patients, 12 achieved complete remission (CR) (34%, 90%CI 21‐50%); 30‐day mortality was 6% and 60‐day mortality 13%. The median OS for all patients was 11.5 months. Among 17 patients treated at the MTD, 7 attained CR (41%); the median OS was not reached while 12‐month OS was 61%. Following therapy with MEC and lenalidomide, patient CD4+ and CD8+ T‐cells demonstrated increased inflammatory responses to autologous tumor lysate. The combination of MEC and lenalidomide is tolerable with an RP2D of lenalidomide 50 mg/d days 1‐10, yielding encouraging response rates. Further studies are planned to explore the potential immunomodulatory effect of lenalidomide and MEC.

Kurzfassung: Introduction: Outcomes for acute myeloid leukemia (AML) among older patients has remained largely unchanged for decades. Long-term survival for patients aged & gt;60 years is poor (median survival 10.5 months). Targeting the proteasome in AML is attractive, since leukemia stem cells have demonstrated sensitivity to proteasome inhibition in preclinical models, perhaps through down regulation of nuclear NF-KB (Guzman, Blood 2001). AML cell lines are susceptible to synergistic cytotoxicity when bortezomib, a proteasome inhibitor, is combined with daunorubicin and cytarabine. We have shown that adding bortezomib to standard treatment in AML results in a high remission rate, although grade 2 sensory neurotoxicity was noted in approximately 12% of treated patients. A newer generation proteasome inhibitor, ixazomib, is less frequently associated with neurotoxicity, and, therefore, was selected for combination with conventional chemotherapy in this phase I trial. The primary objective of this study was to determine the maximum tolerated dose (MTD) of ixazomib in combination with conventional induction and consolidation chemotherapy for AML. Herein are the initial results of this trial. Methods: Adults & gt;60 years of age with newly diagnosed AML were screened for eligibility. Patients with secondary AML were eligible, including those with prior hypomethylating agent therapy for myelodysplastic syndromes (MDS). We excluded those with promyelocytic leukemia. There were 2 phases in this study. In the first phase (A), the induction treatment consisted of the following: cytarabine 100 mg/m2/day by continuous IV infusion, Days 1-7; daunorubicin 60 mg/m2/day IV, Days 1, 2, 3, and ixazomib was provided orally at the cohort dose, Days 2, 5, 9, and 12. Consolidaton or transplant was at the discretion of the treating physician in phase A. In the second phase (B), induction was the same as that with the determined MTD of ixazomib. All patients were to be treated with the following consolidation: cytarabine at 2 g/m2/day, days 1-5 with ixazomib on days 2, 5, 9, and 12 at the cohort dose for consolidation. A standard 3 + 3 patient cohort dose escalation design was used to determine whether the dose of ixazomib could be safely escalated in 3 cohorts (1.5 mg/day, 2.3 mg/day, 3.0 mg/day), initially in induction (phase A) and subsequently in consolidation (phase B). The determined MTD of ixazomib in the first portion (A) of the trial was used during induction in the second portion (B), which sought to determine the MTD for ixazomib during consolidation. Secondary objectives included rate of complete remission, disease-free survival, and overall survival (OS). Results: Thirty-six patients have been enrolled on study, and 28 have completed dose levels A-1 through A-3 and B1 through B-2. Full information on cohort B-3 has not yet been obtained, hence, this report covers the experience with the initial 28 patients, cohorts A-1 through B-2. There were 12 (43%) patients among the 28 with secondary AML, either with prior hematologic malignancy or therapy-related AML. Nineteen patients (68%) were male, and the median age was 68 years (range 61-80 years). There have been no grade 5 toxicities due to study drug. Three patients died early due to leukemia, 2 of which were replaced for assessment of the MTD. Nearly all the grade 3 and 4 toxicities were hematologic (Table). There was 1 DLT (grade 4 platelet count decrease extending beyond Day 42). There has been no grade 3 or 4 neurotoxicity with ixazomib to date. Among the 28 patients in the first 5 cohorts, 22 achieved complete remissions (CR) and 2 achieved CRi, for a composite remission rate (CCR) of 86%. Among the 12 patients with secondary AML 8 achieved CR and 2 achieved CRi, for a CCR of 83%. The median OS for the 28 patients has not been reached (graph). The 18-month OS estimate was 65% [90% CI, 50-85%]. Conclusions: The highest dose level (3 mg) of ixazomib planned for induction in this trial has been reached safely. For consolidation there have been no serious safety issues in the first 2 cohorts with a dose up to 2.3 mg, apart from 1 DLT in the form of delayed platelet count recovery. The recommended phase 2 dose of ixazomib for induction is 3 mg. Accrual to cohort B-3 is ongoing. Notably, to date, no grade 3 or 4 neurotoxicity has been encountered. The remission rate in this older adult population with the addition of ixazomib to standard chemotherapy appears favorable. Figure Disclosures Amrein: Amgen: Research Funding; AstraZeneca: Consultancy, Research Funding; Takeda: Research Funding. Attar:Aprea Therapeutics: Current Employment. Brunner:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Takeda: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding. Hobbs:Constellation: Honoraria, Research Funding; Novartis: Honoraria; Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding; Jazz: Honoraria; Celgene/BMS: Honoraria. Neuberg:Celgene: Research Funding; Madrigak Pharmaceuticals: Current equity holder in publicly-traded company; Pharmacyclics: Research Funding. Fathi:Blueprint: Consultancy; Boston Biomedical: Consultancy; BMS/Celgene: Consultancy, Research Funding; Novartis: Consultancy; Kura Oncology: Consultancy; Trillium: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Abbvie: Consultancy; Pfizer: Consultancy; Newlink Genetics: Consultancy; Forty Seven: Consultancy; Trovagene: Consultancy; Kite: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; Amphivena: Consultancy; PTC Therapeutics: Consultancy; Agios: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Jazz: Consultancy. OffLabel Disclosure: Ixazomib is FDA approved for multiple myeloma. We are using it in this trial for acute myeloid leukemia.

Kurzfassung: Characterization of pathogenic alterations in acute myeloid leukemia (AML) has led to development of promising targeted therapies, including FLT3 (FLT3i) and IDH1/2 inhibitors (IDHi), with several approved for use; midostaurin (MIDO), gilteritinib, enasidenib (ENA), and ivosidenib (IVO). A proportion of patients (pts) have concurrentFLT3andIDHmutations at diagnosis or develop a second mutation during therapy.FLT3mutations, in particular, are associated with poor response rates to IDHi therapy, and treatment-emergentFLT3mutations also appear to confer therapeutic resistance to these agents. There is therefore growing interest to study combined therapies that target multiple pathways, but the clinical experience with combined IDHi and FLT3i therapy has not yet been reported. We performed a retrospective data collection and analysis at 5 institutions (Massachusetts General Hospital, University of Pennsylvania, Johns Hopkins University, University of California San Francisco, and MD Anderson). Using de-identified information from institutional databases, pts treated with concurrent IDHi and FLT3i were identified. Collected data included demographic data, date of initial diagnosis, number of prior therapies, prior hematopoietic cell transplant (HCT), prior targeted therapy, type ofIDHandFLT3mutation, concurrent mutations and cytogenetics, duration of concurrent therapy, therapy-related toxicity, best response, toxicities, and vital status. We identified 12 pts who received concurrent IDHi and FLT3i therapy, 11 of which had relapsed/refractory (R/R) AML. Median age was 57 (range 31-84) and 9 (75%) were male. 7 (58%) were Caucasian, 3 (25%) African American, and 2 (17%) Asian. All pts had intermediate-risk cytogenetics.IDH1R132 mutations were detected in 3 (25%), andIDH2R140 mutations in 9 (75%) pts. OneIDH2mutation arose at relapse. All pts hadFLT3-ITDmutations, and for 3 (38%), this mutation was known to have emerged at relapse. Common concurrent mutations includedDNMT3A(75%) andNPM1(58%). Median number of prior lines of therapy was 2 (range 0-6), and 4 pts (33%) had underwent prior HCT. Six pts (50%) had received FLT3i monotherapy in a prior line of treatment; 4 sorafenib, 1 gilteritinib, 1 MIDO, and 1 with FF-10101 (one pt had 2 prior lines of FLT3i). Six pts were initiated on concurrent therapy in simultaneous fashion, and the remainder were sequential; 2 pts (17%) were on IDHi therapy to which the FLT3i was added, and 4 (33%) had been on FLT3i with subsequent IDHi addition. Four pts (33%) received concurrent gilteritinib and ENA, 3 (25%) received gilteritinib and IVO, 3 (25%) received sorafenib and ENA, and 2 (17%) MIDO and ENA. Three pts received hypomethylating therapy concurrent with combined FLT3i/IDHi therapy; 2 received azacitidine (AZA) with ENA/MIDO, and 1 received AZA with ENA/gilteritinib. Pts were on concurrent therapy for a median of 75 days (range 9-343). Two pts had rash attributable to sorafenib, leading to temporary treatment pause in one and discontinuation in the other. No other toxicities were thought to be related to concurrent treatment. Four pts (33%) achieved CR or CRi (2 CR, 2 CRi), all with persistence of molecular residual disease (MRD). The median duration of remission for these pts was 310 days (range 85-326), and 3 have since relapsed. One pt experienced MLFS, 1 had peripheral blast reduction and 1 had improvement in platelets. An additional pt had MRD(+) CR (byNPM1PCR) on gilteritinib prior to addition of ENA, and then achieved MRD(-) CR with dual therapy. The 4 remaining pts did not respond to concurrent treatment. Two pts (17%) were effectively bridged to HCT following dual therapy. Five pts (42%) remain alive. In this retrospective analysis, a notable proportion of pts benefitted from concurrent FLT3i and IDHi therapy. Composite remission rate was 33%, and overall response rate (CR+CRi+MLFS) was 42% among a largely R/R patient cohort, the majority of whom had received IDHi or FLT3i monotherapy in a prior line of treatment. An additional pt in MRD(+) CR cleared MRD following concurrent treatment. Concurrent therapy appeared to be largely well-tolerated. These response rates are particularly intriguing, given the presence ofFLT3/ITDmutations, alterations thought to confer resistance to IDHi monotherapy. Larger, prospective studies are needed to fully assess the promise of concurrent FLT3i and IDHi therapy in co-mutated pts with AML. Disclosures Fathi: Amphivena:Consultancy;Astellas:Consultancy;Trillium:Consultancy;Amgen:Consultancy;Seattle Genetics:Consultancy, Research Funding;Abbvie:Consultancy;Pfizer:Consultancy;Newlink Genetics:Consultancy;Forty Seven:Consultancy;Trovagene:Consultancy;Kite:Consultancy;BMS/Celgene:Consultancy, Research Funding;Novartis:Consultancy;Daiichi Sankyo:Consultancy;Kura Oncology:Consultancy;Blueprint:Consultancy;PTC Therapeutics:Consultancy;Agios:Consultancy, Research Funding;Takeda:Consultancy, Research Funding;Jazz:Consultancy;Boston Biomedical:Consultancy.Perl:Arog Pharmaceuticals Inc:Other: uncompensated consulting, travel costs for meetings;Astellas:Consultancy, Honoraria, Other: writing/editorial support, travel costs for meeting presentations related to study, Research Funding;AbbVie Inc:Consultancy, Honoraria, Other, Research Funding;Syndax:Consultancy, Honoraria;Takeda:Honoraria, Other: Travel costs for meeting;Leukemia & Lymphoma Society, Beat AML:Consultancy;Novartis:Honoraria, Other, Research Funding;Actinium Pharmaceuticals Inc:Consultancy, Honoraria, Research Funding;Daiichi Sankyo:Consultancy, Honoraria, Other: Writing/editorial support, travel costs for meetings, Research Funding;FUJIFILM Pharmaceuticals USA, Inc:Research Funding;New Link Genetics:Honoraria, Other;Bayer HealthCare Pharmaceuticals:Research Funding;Biomed Valley Discoveries:Research Funding;Loxo Oncology Inc, a wholly owned subsidiary of Eli Lilly & Company:Consultancy, Honoraria, Other;Jazz:Honoraria, Other;Agios:Consultancy, Honoraria, Other;FORMA Therapeutics:Consultancy, Honoraria, Other.Levis:Menarini:Honoraria;Amgen:Honoraria;FujiFilm:Honoraria, Research Funding;Daiichi-Sankyo:Honoraria;Astellas:Honoraria, Research Funding.Smith:Daiichi Sanyko:Consultancy, Honoraria;Abbvie:Other: Research Support, Research Funding;FujiFilm:Other: Research support, Research Funding;Astellas Pharma:Honoraria, Other: Research Support, Research Funding;Revolution Medicines:Other: Research Support, Research Funding;Sanofi:Honoraria.Brunner:Forty-Seven Inc:Membership on an entity's Board of Directors or advisory committees;AstraZeneca:Research Funding;Takeda:Research Funding;Celgene:Membership on an entity's Board of Directors or advisory committees, Research Funding;Novartis:Research Funding;Jazz Pharmaceuticals:Membership on an entity's Board of Directors or advisory committees.Amrein:Amgen:Research Funding;AstraZeneca:Consultancy, Research Funding;Takeda:Research Funding.Hobbs:Merck:Research Funding;Constellation:Honoraria, Research Funding;Incyte:Research Funding;Bayer:Research Funding;Celgene/BMS:Honoraria;Novartis:Honoraria;Jazz:Honoraria.Narayan:Sanofi-Genzyme:Other: Current Spouse employment ;Takeda:Other: Prior Spouse employment within 24 months;Genentech:Other: Prior Spouse employment within 24 months and prior spouse equity divested within past 24 months.Daver:Pfizer:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Karyopharm:Research Funding;Servier:Research Funding;Daiichi Sankyo:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Genentech:Research Funding;AbbVie:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Astellas:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Novimmune:Research Funding;Gilead:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Amgen:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding;Trovagene:Research Funding;Fate Therapeutics:Research Funding;ImmunoGen:Research Funding;Novartis:Consultancy, Membership on an entity's Board of Directors or advisory committees;Celgene:Consultancy, Membership on an entity's Board of Directors or advisory committees;Jazz:Consultancy, Membership on an entity's Board of Directors or advisory committees;Trillium:Consultancy, Membership on an entity's Board of Directors or advisory committees;Syndax: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;KITE:Consultancy, Membership on an entity's Board of Directors or advisory committees;Agios:Consultancy, Membership on an entity's Board of Directors or advisory committees;Bristol-Myers Squibb:Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.DiNardo:Calithera:Research Funding;Celgene:Consultancy, Honoraria, Research Funding;Agios:Consultancy, Honoraria, Research Funding;Syros:Honoraria;Daiichi Sankyo:Consultancy, Honoraria, Research Funding;Notable Labs:Membership on an entity's Board of Directors or advisory committees;Jazz:Honoraria;ImmuneOnc:Honoraria;Takeda:Honoraria;MedImmune:Honoraria;Novartis:Consultancy;AbbVie:Consultancy, Honoraria, Research Funding. OffLabel Disclosure: Midostaurin for relapsed/refractory AML Sorafenib for relapsed/refractory AML

Kurzfassung: Introduction: Treatment of acute myeloid leukemia (AML) has remained largely unchanged for several decades despite the emergence of new agents. Long-term survival for patients aged 〉 60 years is less than 10% (median survival 10.5 months). Targeting the proteasome in treating AML is attractive, since leukemia stem cells have demonstrated sensitivity to proteasome inhibition, perhaps through down regulation of nuclear NF-KB (Guzman, Blood 2001). Preclinical studies in leukemia cell lines revealed synergistic cytotoxicity when bortezomib, a proteasome inhibitor, was combined with the standard agents daunorubicin and cytarabine. We have shown that adding bortezomib to standard treatment in AML results in a high remission rate, although neurotoxicity was noted among treated patients, 12% grade 3 sensory (Attar, …, Amrein, et al. Clin Cancer Res 2008, Attar, … Amrein, J Clin Oncol 2012). The next generation proteasome inhibitor, ixazomib, which is less frequently associated with neurotoxicity, was therefore selected for combination with conventional chemotherapy in this phase I trial. The primary objective was to determine the maximum tolerated dose (MTD) in the combination, initially in induction, and then in combination with consolidation in a subsequent portion of the overall study. We report here the results of the induction portion of the study, which has been completed. Methods: Adults 〉 60 years of age with newly diagnosed AML were screened for eligibility. Patients with secondary AML were eligible, including those with prior hypomethylating agent therapy for myelodysplastic syndromes (MDS). We excluded those with promyelocytic leukemia. The induction treatment consisted of the following: cytarabine 100 mg/m2/day by continuous IV infusion, Days 1-7; daunorubicin 60 mg/m2/day IV, Days 1, 2, 3; ixazomib orally at the cohort dose, Days 2, 5, 9, and 12 A standard 3 + 3 patient cohort dose escalation design was used to determine whether the dose of ixazomib could be safely escalated in 3 cohorts (1.5 mg/day, 2.3 mg/day, 3.0 mg/day), initially in induction and subsequently in consolidation. The dose of 3.0 mg/day was the maximum planned for this study. The determined MTD of ixazomib in the first portion of the trial would be used during induction in the second portion, which seeks to test dose escalation of ixazomib during consolidation. Secondary objectives included rate of complete remission and disease-free survival. Results: Fourteen patients have been analyzed for toxicity and activity during the induction portion of the study. There were 4 (28%) patients with either secondary AML or treatment related AML, 9 (64%) were male, and the median age was 67 years (range 62-80 years). There have been no grade 5 toxicities due to study drug. Three patients died early due to leukemia, 2 of which were replaced for assessment of the MTD. Nearly all the grade 3 and 4 toxicities were hematologic (Table). There was 1 DLT (grade 3 thrombocytopenia) indicated at the highest dose level. There has been no neurotoxicity with ixazomib to date. Among the 14 patients, there have been 10 complete remissions (CR's) and 1 CRi for a remission rate of 79%. Conclusions: The highest dose level planned for this portion of the trial, 3.0 mg of ixazomib, was reached with 1 DLT and is the recommended dose for induction in the next portion of this study, which will seek to determine a safe ixazomib dose in combination with conventional consolidation therapy. That no neurotoxicity was encountered was reassuring, and the remission rate in this older adult population is favorable. Table. Table. Disclosures Amrein: Takeda: Research Funding. Attar:Agios: Employment, Equity Ownership. Brunner:Takeda: Research Funding; Novartis: Research Funding; Celgene: Consultancy, Research Funding. Fathi:Celgene: Consultancy, Honoraria, Research Funding; Boston Biomedical: Consultancy, Honoraria; Astellas: Honoraria; Agios: Honoraria, Research Funding; Jazz: Honoraria; Seattle Genetics: Consultancy, Honoraria; Takeda: Consultancy, Honoraria.

Kurzfassung: Introduction: While progress has been made in the treatment of childhood leukemia, the outlook for patients & gt;60 years of age with acute lymphoblastic leukemia (ALL) is poor with complete remission rates (CR) of approximately 60% and 3-year survivals (OS) of less than 15%. Intensified treatment in a later CALGB trial showed little improvement with a CR=61% and 5-year OS=6% (Stock, Cancer 2013). Ixazomib is an oral proteasome inhibitor, which has shown single agent activity and promising combination activity in pediatric ALL patients (Messinger, Blood 2012). We sought to assess the safety and tolerability, as well as early efficacy of adding ixazomib to a current MGH-DFCI/HCC multi-agent regimen for older adults with ALL. Methods: Patients aged 51 to 75 years of age with newly diagnosed B-ALL and T-ALL were screened for eligibility. Patients with mature ALL (including Burkitt's) were excluded. Patients with Philadelphia chromosome positive ALL (BCR-ABL1+) were eligible, and dasatinib was added to the chemotherapy on Day 10 for these patients. The chemotherapy treatment schedule from induction through maintenance is outlined in Table 1. A standard 3 + 3 patient cohort dose escalation design was used to determine the maximum tolerated dose (MTD) of ixazomib during induction for these patients, the primary objective of the trial. After consolidation I, patients in complete remission (CR) with a suitable donor were offered a hematopoietic stem cell transplantation (HSCT) as per institutional guidelines. Those not going to HSCT continued therapy as noted in the table. Results: There were 19 patients with B-ALL enrolled, none with T-ALL. Among these patients, 7 harbored BCR-ABL1 rearrangements. The median age was 65 years, 74% were male, and 90% had a performance status 0 or 1. The MTD was 2.3 mg of ixazomib, as 2 patients at 3.0 mg developed DLT's: a grade 3 peripheral neuropathy and a grade 5 acute kidney injury (Table 2). Grade 3 and 4 toxicities encountered at any time consisted mainly of grade 4 neutropenia in 13 patients and grade 4 thrombocytopenia in 12 patients. One patient experienced grade 3 neutropenia and 5 patients experienced grade 3 thrombocytopenia. Two patients with grade 2 neuropathy did not meet the definition of DLT. Among the 19 patients, 15 (79%, [95% confidence interval (CI), 54-94%]) achieved CR (14) or CRi (1), and 5 patients went on to HSCT. The median follow-up time was 2 years (range, 1-5) for 8 patients remaining alive. The 1-year overall survival estimate was 53% [95% CI, 29-72%] , while the 2-year overall survival estimate was 47% [95% CI, 24-67%]. Conclusions: A dose of 2.3 mg of ixazomib in combination with induction chemotherapy among older patients with ALL was well-tolerated and associated with a promising rate of complete remission. Disclosures Amrein: Takeda: Research Funding; AstraZeneca: Consultancy, Research Funding; Amgen: Research Funding. Brunner:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; AstraZeneca: Research Funding; Forty-Seven Inc: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Hobbs:Novartis: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria; Constellation: Honoraria, Research Funding; Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding. Neuberg:Celgene: Research Funding; Pharmacyclics: Research Funding; Madrigak Pharmaceuticals: Current equity holder in publicly-traded company. Fathi:Takeda: Consultancy, Research Funding; Agios: Consultancy, Research Funding; PTC Therapeutics: Consultancy; Amphivena: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy; Novartis: Consultancy; Newlink Genetics: Consultancy; Pfizer: Consultancy; Blueprint: Consultancy; Trillium: Consultancy; Kura Oncology: Consultancy; Forty Seven: Consultancy; Jazz: Consultancy; Boston Biomedical: Consultancy; BMS/Celgene: Consultancy, Research Funding; Kite: Consultancy; Trovagene: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Abbvie: Consultancy. OffLabel Disclosure: MLN 9708, ixazomib is FDA approved for multiple myeloma. In this trial it is used to treat acute lymphoblastic leukemia.

Kurzfassung: Characterization of molecular alterations in acute myeloid leukemia (AML) has led to development of targeted therapies, including FLT3 and IDH1/2 inhibitors. Maintenance therapy following hematopoietic cell transplantation (HCT) has shown substantial promise. Enasidenib (ENA), a selective IDH2 inhibitor, was associated with impressive rates of response in relapsed/refractory (R/R) AML and is now FDA-approved for this indication. We sought to assess the tolerability and define the maximum tolerated dose (MTD) of ENA as maintenance following HCT for IDH2-mutated myeloid malignancy. HCT-eligible patients (pts) ≥ 18 years with AML in remission, or myelodysplastic syndrome (MDS) with & lt;5% marrow blasts, were enrolled. There were no restrictions on conditioning or donor type. A 2-step registration process was utilized; 1 before HCT and 1 before ENA initiation. Before HCT, pts were required to have normal organ and recovered marrow function (neutrophils & gt; 1000/µL and platelets & gt; 50000/µL). Those with prior HCT, active disease, QTc ≥450ms, and active infections were excluded. ENA was initiated between day 30 and 90 after HCT, at which time the following were required: chimerism ≥70% of donor origin among blood/marrow cells, no acute graft versus host disease (aGVHD) requiring ≥0.5mg/kg/day prednisone or equivalent, and no relapse. ENA was taken orally (po) daily (qd) in 28-day cycles. The period for dose-limiting toxicity (DLT) evaluation was the first cycle, escalation to successive levels was guided by DLT incidence, and 2 levels (50mg,100mg) were studied. Following establishment of MTD or recommended phase 2 dose (RP2D), 10 pts would be enrolled in an expansion cohort. Pts were monitored for relapse and toxicity and continued until disease progression, intolerable toxicity, or receipt of 12 cycles. Nineteen pts have been registered prior to HCT at 3 sites, Massachusetts General Hospital, Dana Farber Cancer Institute, and Johns Hopkins Hospital. Three pts could not initiate ENA following HCT; 2 due to logistic challenges of the COVID pandemic and 1 due to relapse. The remaining 16 pts initiated ENA treatment. The median age was 61 years (range 31-76); 12 (75%) were male, and 13 (81%) were Caucasian. Fourteen (88%) had AML, of which 6 were AML with MDS related changes and 2 had antecedent myeloproliferative neoplasm. Two pts (13%) had MDS. Among these 16 pts, 9 (56%) had IDH2 R140, and 5 (25%) had IDH2 R172 mutations. IDH2 subtype data was unavailable for 2 pts. Of 15 pts with available data from time of diagnosis, 11 (73%) had intermediate-risk and 4 (27%) had adverse-risk cytogenetics. Among these 15 pts, common concurrent mutations were DNMT3A (47%), SRSF2 (33%), and RUNX1 (33%). Eleven AML pts (85%) received intensive versus non-intensive therapies (15%) prior to HCT, and among all pts, 7 (44%) had received ENA prior to HCT. HCT data was available for all 16 pts; 4 pts (25%) received myeloablative, and 12 (75%) received reduced-intensity conditioning. Nine pts (56%) had a matched unrelated, 6 (38%) had haploidentical, and 1 (6%) had a matched related donor HCT. Three pts were enrolled at the 50mg dose level, 6 pts at 100mg, and after no DLTs were detected, the remaining were enrolled in an expansion cohort at 100mg qd. Median follow-up (F/U) for surviving patients is currently 11.7 months (range 1.5-18.9). 2 pts (13%) have relapsed during F/U, at 96 and 364 days post HCT. Additional ≥grade (G) 3 toxicities detected during treatment, possibly or probably related to ENA, included neutropenia, anemia, and bilirubinemia. Six pts (38%) required dose interruptions lasting a median 19 days (range 7-25), 4 required a dose reduction to 50mg, and 1 stopped treatment due to G3 bilirubinemia. In total, 3 pts (18%) discontinued study treatment, 1 for aforementioned G3 bilirubinemia, 1 to pursue a GVHD trial, and 1 for relapse. Six pts have completed the 12-month f/u without relapse, and 7 remain on study. 15 of 16 pts remain alive. Thus far, 3 pts have experienced ≥ G2 aGVHD, and 4 had moderate chronic GVHD. Serial measurement of 2HG is being conducted on samples, and these will be reported. Enasidenib is well-tolerated as post-HCT maintenance therapy for myeloid malignancy at the RP2D of 100mg qd. No DLTs have been detected, and a low rate of post-HCT relapse has been identified to date, although longer f/u is needed. Larger, randomized studies of ENA in the post-SCT setting would determine the true efficacy of this agent as maintenance therapy. Disclosures Fathi: Blueprint: Consultancy; Jazz: Consultancy; Amgen: Consultancy; Newlink Genetics: Consultancy; Pfizer: Consultancy; Abbvie: Consultancy; Seattle Genetics: Consultancy, Research Funding; Agios: Consultancy, Research Funding; PTC Therapeutics: Consultancy; Takeda: Consultancy, Research Funding; Boston Biomedical: Consultancy; Amphivena: Consultancy; BMS/Celgene: Consultancy, Research Funding; Kite: Consultancy; Trovagene: Consultancy; Forty Seven: Consultancy; Novartis: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; Trillium: Consultancy; Kura Oncology: Consultancy. Soiffer:Gilead: Consultancy; Novartis: Consultancy; Juno: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; VOR Biopharma: Consultancy; alexion: Consultancy; Rheos Therapeutics: Consultancy; Cugene: Consultancy; Precision Bioscience: Consultancy; Be the Match/ National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Kiadis: Membership on an entity's Board of Directors or advisory committees; Mana Therapeutics: Consultancy. Levis:Menarini: Honoraria; Amgen: Honoraria; FujiFilm: Honoraria, Research Funding; Astellas: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria. Mims:Novartis: Speakers Bureau; Kura Oncology: Membership on an entity's Board of Directors or advisory committees; Leukemia and Lymphoma Society: Other: Senior Medical Director for Beat AML Study; Agios: Consultancy; Syndax Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Other: Data Safety Monitoring Board; Abbvie: Membership on an entity's Board of Directors or advisory committees. Devine:Magenta Therapeutics: Consultancy. Defilipp:Incyte: Research Funding; Regimmune: Research Funding; Syndax Pharmaceuticals: Consultancy. Spitzer:Jazz Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Bluebird Bio: Membership on an entity's Board of Directors or advisory committees. Frigault:Celgene: Consultancy; Arcellx: Consultancy; Novartis: Consultancy, Research Funding; Gilead/Kite: Consultancy, Research Funding. Amrein:Amgen: Research Funding; AstraZeneca: Consultancy, Research Funding; Takeda: Research Funding. Hobbs:Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding; Constellation: Honoraria, Research Funding; Jazz: Honoraria; Celgene/BMS: Honoraria; Novartis: Honoraria. Brunner:Janssen: Research Funding; Acceleron Pharma Inc.: Consultancy; GSK: Research Funding; Xcenda: Consultancy; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Jazz Pharma: Consultancy; Forty Seven, Inc: Consultancy; Celgene/BMS: Consultancy, Research Funding; Biogen: Consultancy; Astra Zeneca: Research Funding. Narayan:Genentech: Other: Prior Spouse employment within 24 months and prior spouse equity divested within past 24 months; Takeda: Other: Prior Spouse employment within 24 months; Sanofi-Genzyme: Other: Current Spouse employment . Chen:AbbVie: Other: Data and Safety Monitoring Board Member; Incyte Corporation: Consultancy; Takeda: Consultancy; Actinium: Other: Data and Safety Monitoring Board Member; Equillium: Other: Data and Safety Monitoring Board Member; Magenta: Consultancy; Kiadis: Consultancy. OffLabel Disclosure: Enasidenib as post-transplant maintenance therapy