Preclinical data suggest a rationale for combining CPX-351, a dual-drug liposomal encapsulation of daunorubicin and cytarabine, with venetoclax, a B-cell lymphoma-2 (BCL-2) inhibitor. This phase 1b study evaluated lower-intensity CPX-351 combined with venetoclax in adults with acute myeloid leukemia (AML) considered unfit/ineligible for intensive chemotherapy. In a dose-exploration phase using a 3+3 design, patients received stepwise dosing of CPX‑351 intravenously on days 1 and 3 plus venetoclax 400 mg orally on days 2-21 per cycle to determine the recommended phase 2 dose (RP2D) for this combination. During the expansion phase, additional patients received CPX-351 plus venetoclax at the identified RP2D. The primary endpoints were the RP2D and safety of CPX‑351 combined with venetoclax. Secondary endpoints included preliminary efficacy and pharmacokinetics. Overall, 35 patients were enrolled in the study. A RP2D of CPX-351 30 units/m2 (daunorubicin 13.2 mg/m2 and cytarabine 30 mg/m2) plus venetoclax 400 mg was established. The safety profile of the combination was consistent with the known safety profiles of CPX-351 and venetoclax. Complete remission (CR)/CR with incomplete hematologic recovery (CRi) was achieved by 17/35 (49%) patients, all after cycle 1; of these, 14 were negative for measurable residual disease. CR was achieved by 1/8 (13%) patients with a mutation in TP53, and CR/CRi was achieved by 15/26 (58%) patients with wild-type TP53. This study highlights that lower-intensity therapy of CPX-351 plus venetoclax as induction therapy provides a well-tolerated treatment option in adults with AML deemed unfit for intensive chemotherapy. This trial was registered at www.clinicaltrials.gov as #NCT04038437.
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