Safety and durability of ponatinib in patients with Philadelphia chromosome-positive (Ph+) leukemia: Long-term follow-up of an ongoing phase I study.

Abstract

7063 Background: Ponatinib is a potent oral pan–BCR-ABL tyrosine kinase inhibitor (TKI) that is active against native and mutated forms of BCR-ABL. The safety and anti-leukemic activity of ponatinib in patients (pts) with chronic myeloid leukemia (CML) or Ph+ acute lymphoblastic leukemia (ALL) were evaluated in a phase I clinical trial. Methods: Pts (N=81) with resistant/refractory hematologic malignancies were enrolled in this ongoing, open-label, dose escalation, phase I study. Ponatinib was dosed once daily (2–60 mg). 65 pts had Ph+ leukemia and are included in the present analysis (data as of 9 Nov 2012). Median follow-up was 25 (0.5–44) mos. Results: The median age of pts was 55 yrs; median time since diagnosis was 6.5 yrs. Pts were heavily pretreated (94% had received ≥2 prior TKIs, 62% ≥3). 65% had baseline BCR-ABL mutations. 46% (67% chronic phase [CP] CML) of pts remained on study. Progression and adverse events (AEs) were the most common reasons for discontinuation (17% each). The most common treatment-related AEs were rash (42%), thrombocytopenia (34%), arthralgia (20%), and increased lipase (20%). Significant anti-leukemic activity was observed (Table). Responses (major cytogenetic response [MCyR] for CP-CML or major hematologic response [MaHR] for accelerated phase [AP] CML, blast phase [BP] CML, or Ph+ ALL) were observed against the following mutations detected in >1 pt at baseline: 14/19 T315I, 4/7 F317L, 2/4 G250E, 2/2 M244V, 2/2 M35IT, and 1/2 F359V. Among CP-CML pts, 73% with complete cytogenetic response (CCyR) and 63% with major molecular response (MMR) are estimated to maintain response at 2 yrs (Kaplan-Meier). Of 28 CP-CML pts with CCyR, 25 remained on study (19 with continuous CCyR); of 22 pts with MMR, 21 remained on study (15 with continuous MMR). Updated data will be presented. Conclusions: Significant and durable responses were observed in heavily pretreated CP-CML pts, regardless of mutation status, and ponatinib was generally well tolerated. Clinical trial information: NCT00660920. [Table: see text]