Phase I/II Study of Combination Therapy With Sorafenib, Idarubicin, and Cytarabine in Younger Patients With Acute Myeloid Leukemia

PURPOSE To determine the efficacy and toxicity of the combination of sorafenib, cytarabine, and idarubicin in patients with acute myeloid leukemia (AML) younger than age 65 years. PATIENTS AND METHODS In the phase I part of the study, 10 patients with relapsed AML were treated with escalating doses of sorafenib with chemotherapy to establish the feasibility of the combination. We then treated 51 patients (median age, 53 years; range, 18 to 65 years) who had previously untreated AML with cytarabine at 1.5 g/m(2) by continuous intravenous (IV) infusion daily for 4 days (3 days if > 60 years of age), idarubicin at 12 mg/m(2) IV daily for 3 days, and sorafenib at 400 mg orally twice daily for 7 days. RESULTS Overall, 38 (75%) patients have achieved a complete remission (CR), including 14 (93%) of 15 patients with mutated FMS-like tyrosine kinase-3 (FLT3; the 15th patient had complete remission with incomplete platelet recovery CRp) and 24 (66%) of 36 patients with FLT3 wild-type (WT) disease (three additional FLT3-WT patients had CRp). FLT3-mutated patients were more likely to achieve a CR than FLT3-WT patients (P = .033). With a median follow-up of 54 weeks (range, 8 to 87 weeks), the probability of survival at 1 year is 74%. Among the FLT3-mutated patients, 10 have relapsed and five remain in CR with a median follow-up of 62 weeks (range, 10 to 76 weeks). Plasma inhibitory assay demonstrated an on-target effect on FLT3 kinase activity. CONCLUSION Sorafenib can be safely combined with chemotherapy, produces a high CR rate in FLT3-mutated patients, and inhibits FLT3 signaling.