Chemo-free regimen based on venetoclax and azacytidine as induction therapy for adults with newly-diagnosed mixed phenotype acute leukemia

Abstract Introduction Mixed phenotype acute leukemia (MPAL) is a rare type of leukemia with a poor prognosis and lack of standard treatment. Venetoclax (ven) plus azacitidine (aza) has been the standard care for patients with newly-diagnosed acute myeloid leukemia who are unfit for intensive chemotherapy. Methods We retrospectively analyzed the efficacy and safety of the ven-aza-based chemo-free regimen as induction therapy in patients with newly-diagnosed MPAL at the First Affiliated Hospital of Soochow University from July 2021 to October 2023. Results Sixteen patients were enrolled with a median age of 45 years in whom six patients bearing BCR-ABL1 fusion gene. The response rate was 100%, including 9 (56.3%) patients who achieved complete response and 7 (43.7%) patients who achieved complete remission with incomplete blood count recovery. Eight (50%) patients attained measurable residual disease negativity. Thirteen (81.3%) patients received hematopoietic stem cell transplantation (HSCT), 10 of whom underwent HSCT in their first remission. Four (25%) patients experienced relapse, the median time to relapse after remission was 3.7 months. The median follow-up was 30.8 (16.2-43.6) months. The 3-year event-free survival and overall survival were 67.5% (95%CI, 43.8%-91.2%) and 85.7% (95%CI, 67.3%-104.1%), respectively. The severe adverse events were limited to hematologic toxicity and infections and no treatment-related deaths. Conclusions The ven-aza-based chemo-free regimen demonstrated high efficacy and safety in newly-diagnosed MPAL, enabling these patients to receive individualized post-induction strategies and improve long-term prognosis.