On July 20, 2023, the U.S. Food and Drug Administration (FDA) approved quizartinib (Vanflyta) for adult patients newly diagnosed with acute myeloid leukemia (AML) that has FLT3 internal tandem duplication (ITD)-positive mutation, as detected by the FDA-approved LeukoStrat CDx FLT3 Mutation Assay.
Study ID Number NCT02668653
Approval was based on the QuANTUM-First study, a randomized, double-blind, placebo-controlled trial that included 539 patients with newly diagnosed FLT3-ITD-positive AML. Quizartinib was given orally at a dosage of 35.4 mg once daily on days 8-21 during the induction phase with cytarabine and daunorubicin/idarubicin and on days 6-19 of the consolidation phase with high-dose cytarabine for up to 4 cycles.
Subsequently, quizartinib was given at a dose of 26.5 mg once daily on days 1-14 and then 53 mg once daily after that, for maintenance therapy, for up to 36 28-day cycles or until patients’ health indicators dictated discontinuation. Patients who underwent hematopoietic stem cell transplantation (HSCT) started maintenance therapy after recovery from HSCT.
Efficacy was established based on the overall survival rate (OS), the study’s primary endpoint.
After a median follow-up of 24 months, the overall survival for the quizartinib group was statistically significantly improved with a hazard ratio (HR) of 0.78 (95% CI: 0.62, 0.98; 2‑sided p=0.0324) when compared with the placebo group.
The complete response (CR) rate in the quizartinib arm was 55% (95% CI: 48.7, 60.9) with a median duration of 38.6 months (95% CI: 21.9, NE), while that in the placebo group was 55% (95% CI: 49.2, 61.4) with a median duration of 12.4 months (95% CI: 8.8, 22.7).
The side effects of quizartinib include QT prolongation, torsades de pointes, and cardiac arrest. Quizartinib is not recommended as maintenance monotherapy following allogeneic hematopoietic stem cell transplantation (HSCT). The FDA has approved quizartinib (Vanflyta) for adult patients newly diagnosed with FLT3-ITD-positive AML. During induction, quizartinib should be administered orally once daily at a dose of 35.4 mg, during consolidation at the same amount, and during maintenance initially at a dose of 26.5 mg, then increasing to 53 mg.
The medication is available under the Vanflyta Risk Evaluation and Mitigation Strategy (REMS) program due to its potentially severe side effects.
