Phase I study of midostaurin and azacitidine in relapsed and elderly AML.

Abstract

7058 Background: The Fms-like tyrosine kinase 3 (FLT3) receptor is expressed in 80% of AML and activating mutations are associated with an adverse prognosis. Midostaurin (mdn), an orally available agent, has been shown to inhibit FLT3 receptor signaling and induces cell cycle arrest and apoptosis of leukemic cells expressing both mutant and wild type FLT3 receptors. Preliminary data has shown modest single agent activity as well as safety and tolerablility of mdn in combination with standard induction chemotherapy. Methods: We conducted a phase I study of azacitidine (75 mg/m2 iv X 7days) with escalating doses of oral mdn (25 mg bid, 50 mg bid, and 75 mg bid) days 8-21 of a 28 day cycle in untreated elderly and relapsed AML. The protocol was IRB approved at participating institutions and all patients gave written informed consent. Dose limiting toxicities (DLTs) were defined as > grade 3 non-heme toxicity during cycle 1 excluding grade 3 hepatotoxicity < 7 days, grade 3/4 stomatitis or diarrhea that resolved by day 28, infections, and electrolyte abnormalities of any grade. Pharmacokinetics (pK) were obtained on day 8,15, and 21 before mdn dosing. Results: 17 pts (11 females and 6 males) ages 57-83 ( median 73) were enrolled of whom 5 patients had prior intensive treatment for AML. All pts were FLT3 negative; 5 had normal cytogenetics and 12 had high risk cytogenetics. ECOG PS: 0 (4pts), 1 (11pts), 2 (2pts). No DLT were observed during escalation or in the expansion cohort of 75 mg bid. Responses were evaluable in 14/17 pts and included 2 CR, 1 PR, and 2 HI (clearing of peripheral blasts, platelet tx independence). Median survival from enrollment was 3.5 months (range 1-12 months). 4 pts remain on treatment (2- 9+ cycles). 3 pts died within 60 days (2 PD, 1 treatment-related). Non-infectious, non hematologic SAE’s are listed on the table below. Plasma concentrations of mdn accumulated in the first week of treatment and declined thereafter despite continued dosing. Conclusions: The combination of azacitidine and midostaurin in safe and tolerable in elderly AML and should be further studied in FLT3 positive leukemia. Clinical trial information: NCT01093573. [Table: see text]