Background
QuANTUM-First was a phase III randomized double-blind placebo-controlled trial evaluating quizartinib (a highly selective FLT3 inhibitor) added to standard induction, consolidation, and maintenance chemotherapy in newly diagnosed FLT3-ITD–positive AML. FLT3-ITD mutations occur in ~25% of AML and confer poor prognosis. Midostaurin (RATIFY, 2017) established the FLT3 inhibitor + chemotherapy paradigm; QuANTUM-First tested whether a more potent and selective FLT3 inhibitor could improve upon that survival benefit.
Interventions and follow up
Arm A: Standard 7+3 induction → cytarabine consolidation ± allo-SCT → placebo maintenance ×36 cycles (n=271)
Arm B: Standard 7+3 induction + quizartinib → consolidation + quizartinib ± allo-SCT → quizartinib 30–60 mg PO daily maintenance ×36 cycles (n=268)
Primary endpoint: Overall survival; secondary: event-free survival, CR/CRi, safety
mFollow up: 39.2 months
Arm B: Standard 7+3 induction + quizartinib → consolidation + quizartinib ± allo-SCT → quizartinib 30–60 mg PO daily maintenance ×36 cycles (n=268)
Primary endpoint: Overall survival; secondary: event-free survival, CR/CRi, safety
mFollow up: 39.2 months
Results
mOS: 31.9 vs 15.1 months (quizartinib vs placebo), HR 0.78, 95% CI 0.62–0.98, P=.032
EFS: HR 0.916, 95% CI 0.75–1.11 (not significant)
CR: 54.9% vs 55.4% (similar)
Composite CR (CR+CRi): 71.6% vs 64.9%
allo-SCT in CR1: ~44% vs ~40%
EFS: HR 0.916, 95% CI 0.75–1.11 (not significant)
CR: 54.9% vs 55.4% (similar)
Composite CR (CR+CRi): 71.6% vs 64.9%
allo-SCT in CR1: ~44% vs ~40%
Adverse events
Hematologic/infectious (Grade ≥3, quizartinib vs placebo): febrile neutropenia 44% vs 42%; infections 24.1% vs 21.8%
Cardiac: QTc prolongation Grade ≥3 ~3% (key quizartinib-specific toxicity; ECG monitoring and electrolyte management required)
Other: overall Grade ≥3 AEs ~97% both arms; treatment discontinuation due to AEs higher with quizartinib
Cardiac: QTc prolongation Grade ≥3 ~3% (key quizartinib-specific toxicity; ECG monitoring and electrolyte management required)
Other: overall Grade ≥3 AEs ~97% both arms; treatment discontinuation due to AEs higher with quizartinib
Conclusions
Quizartinib added to standard induction, consolidation, and maintenance chemotherapy significantly improved OS in newly diagnosed FLT3-ITD+ AML (HR 0.78, mOS 31.9 vs 15.1 months), establishing it as a new option for fit FLT3-ITD+ patients and demonstrating that potent selective FLT3 inhibition with maintenance extension improves survival over chemotherapy alone.
Key Limitations
Modest OS benefit (HR 0.78); EFS not significantly improved; QTc prolongation requires ECG monitoring and CYP3A4 interaction management; only FLT3-ITD (not TKD) patients eligible; no head-to-head comparison to midostaurin-containing regimens; design does not distinguish benefit attributable to induction/consolidation vs maintenance quizartinib; similar allo-SCT frequency limits attribution of post-transplant maintenance benefit; gilteritinib is now also being studied in the frontline setting.
Clinical Context
QuANTUM-First led to FDA approval (July 2023) of quizartinib with standard induction/consolidation chemotherapy for newly diagnosed FLT3-ITD+ AML — the second frontline FLT3 inhibitor after midostaurin. Both show HR ~0.78 for OS, suggesting a class effect of FLT3 inhibition added to 7+3. The choice between quizartinib and midostaurin involves quizartinib's ECG-monitoring burden versus midostaurin's additional FLT3-TKD activity. Gilteritinib (ADMIRAL) remains R/R standard of care, and ELN guidance incorporates FLT3 inhibitors into frontline FLT3-mutant AML management.