Long-term outcomes in FLT3-mutated acute myeloid leukemia after frontline hypomethylating agent, venetoclax and a FLT3 inhibitor

Abstract

Triplet regimens with a hypomethylating agent, venetoclax and a FLT3 inhibitor yield high rates of response in newly diagnosed FLT3-mutated AML. However, the long-term outcomes and patterns of relapse with these triplet regimens are not well-established. In this retrospective analysis, 73 patients with newly diagnosed FLT3-mutated AML received a frontline FLT3 inhibitor-containing triplet regimen. The composite complete remission (CR) and CR with incomplete hematologic recovery (CRi) rate was 93%. Next-generation sequencing FLT3-ITD MRD negativity (sensitivity: 0.005%) was achieved in 60% of patients after cycle 2 and 90% after cycle 4. The estimated 3-year relapse-free survival (RFS) for FLT3-ITD-mutated and FLT3 TKD-mutated AML was 38% and 76%, respectively, and the 3-year overall survival (OS) was 45% and 76%, respectively. Neither age, NPM1 co-mutation, ELN 2022 risk, nor allogeneic stem cell transplantation in first remission significantly impacted OS. Baseline RAS pathway mutations were associated with poor long-term survival (3-year OS 22% versus 63% without RAS pathway mutation). FLT3 wild type relapses accounted for 65% of relapses, and new RAS pathway mutations were observed in 24% of relapses. Outcomes were poor after relapse (median OS of 6.1 months), particularly for those with persistently detectable FLT3 mutations. Triplet combinations of an HMA, venetoclax and a FLT3 inhibitor result in durable remission and encouraging long-term OS in older adults with newly diagnosed FLT3-mutated AML. However, better strategies to prevent FLT3 wild type relapses and to overcome RAS pathway-mediated resistance are still needed.