A Randomized Phase 2 Trial of 28-Day (Arm A) Versus 14-Day (Arm B) Schedule of Venetoclax + Azacitidine in Newly Diagnosed Acute Myeloid Leukemia Patients ≥ 60 Years

Abstract

Background: Treatment options for older, less fit acute myeloid leukemia (AML) patients continue to be challenging, with toxicities and limited efficacy. The combination therapy of azacitidine (Aza) and the bcl-2 inhibitor venetoclax (Ven) showed superior benefit in response rates and overall survival compared to Aza alone, leading to the combination's FDA approval in newly diagnosed AML patients ≥ 75 years and younger patients ineligible for intensive chemotherapy. While Ven-Aza is a very effective and potent therapy, the 28-day continuous dosing of Ven combined with 7 days of Aza resulted in interrupted dosing or shortened dosing schedules due to persistent cytopenias in more than 50% of treated patients in the VIALE-A trial and subsequent real-world data. Furthermore, investigation of novel agents in combination with Ven-Aza has been challenging due to prolonged cytopenias even when monotherapy with the new agent shows no myelosuppression. Given that Ven-Aza is not curative, successful integration of other agents with this standard of care remains important in AML. The growing knowledge of Ven-Aza toxicities prompted attention to developing a safer dosing regimen while maintaining similar efficacy. Our study will examine the FDA label of 28 days of Ven, versus 14 days, in combination with Aza for newly diagnosed AML patients ≥ 60 years who are not candidates for intensive chemotherapy. The primary objective of this study is to compare complete remission (CR) rates with an abbreviated schedule of Ven (14 days) versus the current package insert approved schedule (28 days). We hypothesize that reducing the dosing duration of Ven would reduce the associated toxicities while maintaining a comparable response rate. Study Design and Methods: This protocol is a sub-study of the Beat AML Master Trial (NCT03013998) in which untreated AML patients age ≥ 60 are assigned an investigational therapy based on cytogenetic and central genomic analysis. Patients are randomized onto Arm A (28-day Ven-Aza schedule) or Arm B (14-day Ven-Aza schedule) stratified by age (60-74 vs. 75+ years). The primary objective is to determine the complete remission (CR) rate of patients treated in each randomized arm for up to 2 cycles. The secondary objectives will include assessments of composite complete remission (CR, CR with hematologic improvement, CR with incomplete count recovery), duration of remission, survival, and incidence of treatment-related and non-related toxicities. Additionally, the overall incidence of febrile neutropenia, grade ≥3 infections, transfusions, days of hospitalization and time to neutrophil recovery will be determined. In both arms of the study, patients will be assessed for response at day 21-28 of cycles 1 and 2. Patients who have marrow remission (< 5% blasts) will wait for count recovery of absolute neutrophil count ≥ 0.5x10 9/L and platelets ≥ 50x10 9/L before initiating the next cycle of therapy. Patients will then be followed for survival. With the exception of the Ven dosing schedule (14 vs. 28 days), the FDA approved package insert for Ven, including dose modifications for concurrent azole therapy, will be followed in both arms. The intent of the analysis is to demonstrate that the 14-day Ven-Aza regimen is at least as effective as the standard 28-day regimen. A total of 166 patients (83 per group) will provide 80% power to detect a 10% non-inferiority margin at the one-sided 5% significance level, assuming that the CR rate is 36% for the 28-day regimen, as observed in VIALE-A, and 25% higher (45%) for the 14-day regimen. In addition to assessing the frequency of adverse events such as cytopenias, safety monitoring will include an assessment of response rates after at least 25% of patients have completed 2 cycles of treatment, with consideration for stopping the study if data suggest the 14-day regimen is inferior to the standard regimen. Correlative studies will include measurement of MRD and a focus on identifying properties of leukemic cells that respond, do not respond and become resistant to therapy.