ImmunoGen presents findings from newly diagnosed AML cohorts in Phase 1b/2 study

ImmunoGen announced new safety and efficacy findings from the newly diagnosed cohorts of the Phase 1b/2 study of pivekimab sunirine in combination with azacitidine and venetoclax in patients with ND acute myeloid leukemia. In the open-label, multicenter, Phase 1b/2 study of pivekimab in combination with azacitidine and venetoclax in patients with ND CD123-positive AML, patients received the recommended Phase 2 dose of pivekimab at 0.045 mg/kg on day 7, azacitidine at 75 mg/m2 daily on days 1-7, and venetoclax at up to 400 mg for at least 14 days or up to 28 days, based on cohort assignment, in a 28-day cycle. The primary endpoints are complete remission rate, composite CR rate, minimal residual disease negativity rate, and duration of remission. Key secondary endpoints are safety, pharmacokinetics, and immunogenicity. In the overall population, CCR rate was 68%, CR rate was 54%, and MRD negativity rate among evaluable patients achieving CCR was 76%. MRD was assessed centrally by flow cytometry with less than0.1% considered negative. Response rates and MRD negativity were numerically comparable between cohorts 1 and 2, despite differences in the venetoclax schedule. In a post hoc subset analysis of patients unfit for intensive chemotherapy, CCR rate was 78%, CR rate was 61%, and MRD negativity rate was 79%. In patients known to be TP53wt, CCR rate was 88%, CR rate was 84%, and MRD negativity rate was 80%. CCR and MRD negativity rates, respectively, were high across other major molecular subsets. Among all MRD negative patients, the median time to MRD negativity was 1.87 months. Although follow-up duration was short, landmark overall survival estimate at 6 months is 86%. The study is continuing to enroll newly diagnosed unfit AML patients. The triplet displayed a manageable safety profile; no new safety signals were observed compared to previously reported data. 30-day mortality was 0%. 60-day mortality was 4%.