Quizartinib for patients with newly diagnosed FLT3-ITD-positive AML who received maintenance therapy in QuANTUM-First.
QuANTUM-First demonstrated improved overall survival (OS) in patients with newly diagnosed acute myeloid leukemia with FMS-like receptor tyrosine kinase 3-internal tandem duplication (FLT3-ITD) treated with quizartinib + standard chemotherapy. Herein, we evaluated the impact of postconsolidation/posttransplant single-agent maintenance therapy on clinical outcomes in patients receiving maintenance, focusing on measurable residual disease (MRD) status at maintenance onset. OS, event-free survival, and relapse-free survival were prespecified exploratory analyses. Cumulative incidence of relapse, analyses by allogeneic hematopoietic cell transplant (allo-HCT), and analyses by MRD status were post hoc and not powered for statistical significance. Samples for FLT3-ITD MRD analysis were collected from patients with composite complete remission ≤30 days before receiving maintenance and assessed using an ultrasensitive amplicon-based assay. More patients who had received an allo-HCT and quizartinib treatment received maintenance (71%) vs placebo (55%); OS benefit was not demonstrated among these patients. In patients who did not undergo allo-HCT, quizartinib maintenance was associated with a significant OS benefit (hazard ratio [HR], 0.401; 95% confidence interval [CI], 0.192-0.838), including a benefit in patients who were MRD negative at the start of maintenance (OS HR, 0.194; 95% CI, 0.056-0.676). Patients who were MRD negative at the completion of consolidation achieved 89.1% (95% CI, 70.0-96.4) survival at 3 years with quizartinib maintenance in the absence of allo-HCT. These data suggest that for patients who achieve FLT3-ITD MRD negativity after induction and consolidation with quizartinib, maintenance with quizartinib provides a significant survival benefit and, in some patients, may eliminate the need for allo-HCT. This trial was registered at www.clinicaltrials.gov as NCT02668653.