Stock, Wendy

Abstract Enasidenib (ENA) is an inhibitor of isocitrate dehydrogenase 2 (IDH2) approved for the treatment of patients with IDH2-mutant relapsed/refractory acute myeloid leukemia (AML). In this phase 2/1b Beat AML substudy, we applied a risk-adapted approach to assess the efficacy of ENA monotherapy for patients aged ≥60 years with newly diagnosed IDH2-mutant AML in whom genomic profiling demonstrated that mutant IDH2 was in the dominant leukemic clone. Patients for whom ENA monotherapy did not induce a complete remission (CR) or CR with incomplete blood count recovery (CRi) enrolled in a phase 1b cohort with the addition of azacitidine. The phase 2 portion assessing the overall response to ENA alone demonstrated efficacy, with a composite complete response (cCR) rate (CR/CRi) of 46% in 60 evaluable patients. Seventeen patients subsequently transitioned to phase 1b combination therapy, with a cCR rate of 41% and 1 dose-limiting toxicity. Correlative studies highlight mechanisms of clonal elimination with differentiation therapy as well as therapeutic resistance. This study demonstrates both efficacy of ENA monotherapy in the upfront setting and feasibility and applicability of a risk-adapted approach to the upfront treatment of IDH2-mutant AML. This trial is registered at www.clinicaltrials.gov as #NCT03013998.

Abstract Acute myeloid leukemia (AML), an aggressive malignancy with unmet medical need, lacks immunotherapeutic options. CD123, the cellular receptor for interleukin-3, expressed in AML is an attractive target for tumor-specific therapy. Vibecotamab (XmAb14045), a humanized bispecific antibody, monovalently binds both CD3 and CD123 to recruit cytotoxic T cells to kill CD123+ tumor cells. This phase 1 study’s primary objectives were safety and tolerability and identification of a maximum tolerated dose/recommended dose for use as monotherapy in patients with relapsed/refractory AML. Identification of a recommended phase 2 vibecotamab dose comprised 3 step-up doses (Week 1), which were noted to reduce cytokine response syndrome (CRS), followed by weekly dosing (1.7 μg/kg, Cohort -1D). In 16 of 120 patients, at least 1 treatment-emergent adverse event was classified as a dose-limiting toxicity. CRS, the most common adverse event (59.2%), managed with premedication, were mostly ≤grade 2. A secondary objective was assessment of efficacy in patients with CD123-expressing leukemias. A total of 10 of 111 (9.0%) efficacy-evaluable patients with AML achieved an overall response of morphologic leukemia-free state or better with an overall objective response rate (ORR) of 9.0%. Response was only observed in patients receiving a target dose of 0.75 μg/kg or higher (n = 87) in which the efficacy-evaluable ORR was 11.5%. Response was associated with lower baseline blast counts in blood and bone marrow (<25%) suggesting potential benefit. This trial was registered at www.clinicaltrials.gov as #NCT02730312.

AbstractNext-generation sequencing (NGS) to identify pathogenic mutations is an integral part of acute myeloid leukemia (AML) therapeutic decision-making. The concordance in identifying pathogenic mutations among different NGS platforms at different diagnostic laboratories has been studied in solid tumors but not in myeloid malignancies to date. To determine this interlaboratory concordance, we collected a total of 194 AML bone marrow or peripheral blood samples from newly diagnosed patients with AML enrolled in the Beat AML Master Trial (BAMT) at 2 academic institutions. We analyzed the diagnostic samples from patients with AML for the detection of pathogenic myeloid mutations in 8 genes (DNMT3A, FLT3, IDH1, IDH2, NPM1, TET2, TP53, and WT1) locally using the Hematologic Neoplasm Mutation Panel (50-gene myeloid indication filter) (site 1) or the GeneTrails Comprehensive Heme Panel (site 2) at the 2 institutions and compared them with the central results from the diagnostic laboratory for the BAMT, Foundation Medicine, Inc. The overall percent agreement was over 95% each in all 8 genes, with almost perfect agreement (κ > 0.906) in all but WT1, which had substantial agreement (κ = 0.848) when controlling for site. The minimal discrepancies were due to reporting variants of unknown significance (VUS) for the WT1 and TP53 genes. These results indicate that the various NGS methods used to analyze samples from patients with AML enrolled in the BAMT show high concordance, a reassuring finding given the wide use of NGS for therapeutic decision-making in AML.

7006 Background: Older adult patients (pts) with Philadelphia-chromosome-negative (Ph-) acute lymphoblastic leukemia (ALL) have poor survival with chemotherapy. The α-CD22 Ab-drug conjugate inotuzumab ozogamicin (InO) and α-CD19/CD3 T-cell engager blinatumomab (blina) were each superior to chemotherapy in Phase III studies in relapsed/refractory B-ALL. Because InO induces high CR rates and blina can induce durable remissions in low burden disease, we conducted a Phase II trial of induction InO then blina for older adults with newly-diagnosed (ND), Ph-, B-ALL. Methods: Eligible were pts ≥60 years old with ND, Ph-, CD22+ (≥20% of blasts) B-ALL without plan for allogeneic HCT (alloHCT). Pts with CNS leukemia or liver disease were excluded. Induction IA was InO 0.8 mg/m 2 day (d) 1, 0.5 mg/m 2 d8, d15 IV on a 21d cycle. Pts with adequate cytoreduction (marrow blasts by ≥50% or cellularity ≤20%) after IA went to IB if in CR/CRi (InO 0.5 mg/m 2 d1, d8, d15 IV; 28d cycle) or IC if no CR/CRi (InO 0.8 mg/m 2 on d1 and 0.5 mg/m 2 on d8 and d15 IV; 28d cycle). Those without cytoreduction to IA started course II blina. Pts without events in IA/B/C received course II blina CIV (9 mcg/d x 7d then 28 mcg/d x 21d; 14d break; 28 mcg/d x28d). Pts with CR/CRi to InO received 2 more 28d cycles of blina, others received 3 more. CNS prophylaxis was methotrexate 15 mg intrathecal x 8. The primary endpoint was 1-yr event-free survival (EFS) with a lower limit of a 90% CI for 1-yr EFS >10% defined as success. EFS was the time from therapy start to failure to achieve CR/CRh/CRi by end Course II, progression, relapse, or death, whichever occurred first. Results: Thirty-three eligible pts were treated (1 ineligible, 2 nd malignancy). The median age was 71 years (range 60-84). Median WBC count was 3,200/mcl (range 6-38,000). Median CD22 expression was 92% (range 21-100%). Eight pts had therapy-related ALL. The cumulative CR rates through Course IA/B/C and Course II were 85% and 97%, respectively (Table). With median follow up of 22 mo, the 1-yr EFS was 75% (95% CI 61-92%). The 2-sided 90% CI was 63-89% for 1-yr EFS with lower bound above 10% indicating regimen success. Twelve pts had events: 9 relapses, 2 deaths in remission (1 after alloHCT), and 1 death without remission from respiratory failure with sinusoidal occlusion syndrome of liver. The 1-yr OS was 84% (95% CI 72-98%). Nine pts have died, 6 after relapse. Conclusions: InO induction then blina consolidation is highly active for ND, Ph-, CD22+ B-ALL. The regimen is an option for older adults and a comparator regimen for future studies. Support: U10CA180821, U10CA180882, U10CA180820 https://acknowledgments.alliancefound.org . Clinical trial information: NCT03739814 . N=33 I A/B/C II Composite CR* 28 ( 85%) 32 ( 97%) CR 15 (45%) 19 (58%) CRh 11 (33%) 12 (36%) CRi 2 (6%) 1 (3%) Refractory 3 (9%) † - 1-yr EFS 75% (95% CI 61-92%) 1-yr OS 84% (95% CI 72-92%) *CR+CRh+CRi † 1 completed IA only

AbstractBackgroundPatients with acute myeloid leukemia (AML) who have tumor protein p53 (TP53) mutations or a complex karyotype have a poor prognosis, and hypomethylating agents are often used. The authors evaluated the efficacy of entospletinib, an oral inhibitor of spleen tyrosine kinase, combined with decitabine in this patient population.MethodsThis was a multicenter, open‐label, phase 2 substudy of the Beat AML Master Trial (ClinicalTrials.gov identifier NCT03013998) using a Simon two‐stage design. Eligible patients aged 60 years or older who had newly diagnosed AML with mutations in TP53 with or without a complex karyotype (cohort A; n = 45) or had a complex karyotype without TP53 mutation (cohort B; n = 13) received entospletinib 400 mg twice daily with decitabine 20 mg/m2 on days 1–10 every 28 days for up to three induction cycles, followed by up to 11 consolidation cycles, in which decitabine was reduced to days 1–5. Entospletinib maintenance was given for up to 2 years. The primary end point was complete remission (CR) and CR with hematologic improvement by up to six cycles of therapy.ResultsThe composite CR rates for cohorts A and B were 13.3% (95% confidence interval, 5.1%–26.8%) and 30.8% (95% confidence interval, 9.1%–61.4%), respectively. The median duration of response was 7.6 and 8.2 months, respectively, and the median overall survival was 6.5 and 11.5 months, respectively. The study was stopped because the futility boundary was crossed in both cohorts.ConclusionsThe combination of entospletinib and decitabine demonstrated activity and was acceptably tolerated in this patient population; however, the CR rates were low, and overall survival was short. Novel treatment strategies for older patients with TP53 mutations and complex karyotype remain an urgent need.

PURPOSE: Clinical trials are important for managing older patients with AML. We investigated differences in outcomes of older patients with AML on the basis of whether patients participated in intensive chemotherapy trials at community versus academic cancer centers. METHODS: We used data from the Alliance for Clinical Trials in Oncology phase III trials that enrolled patients age ≥ 60 years with newly diagnosed AML between 1998 and 2002 in the Cancer and Leukemia Group B (CALGB) 9720 trial and between 2004 and 2006 in the CALGB 10201 trial. Centers funded by the NCI Community Oncology Research Program were identified as community cancer centers; others were designated as academic cancer centers. Logistic regression models and Cox proportional hazards models were used to compare 1-month mortality and overall survival (OS) by center type. RESULTS: Seventeen percent of the 1,170 patients were enrolled in clinical trials in community cancer centers. The study results demonstrated comparable rates of grade ≥3 adverse events (97% v 93%), 1-month mortality (19.1% v 16.1%), and OS (43.9% v 35.7% at 1 year) between community versus academic cancer centers, respectively. After adjusting for covariates, 1-month mortality (odds ratio, 1.40; 95% CI, 0.92 to 2.12; P = .11) and OS (hazard ratio, 1.04; 95% CI, 0.88 to 1.22; P = .67) were not statistically different among patients treated in community versus academic cancer centers. CONCLUSION: An older patient population, who have complex health care needs, can be successfully treated on intensive chemotherapy trials in select community cancer centers with outcomes comparable with that achieved at academic cancer centers.