Early results of lower-dose dasatinib, 50 mg daily, in newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase.

Abstract

e18551 Background: Dasatinib, a potent BCR-ABL tyrosine kinase inhibitor (TKI), is approved for the treatment of chronic phase CML (CML-CP) in the frontline and salvage settings. The approved dose in chronic phase is 100mg orally daily. Notable side effects include pleural effusions and myelosuppression.We evaluated the efficacy and toxicity profile of dasatinib 50mg orally daily in patients with newly diagnosed CML-CP. Methods: Adults with newly diagnosed CML-CP were eligible. Prior TKI therapy for up to 1 month was allowed. Eligibility criteria were standard. Patients received dasatinib 50mg daily. Responses were defined according to the European LeukemiaNet guidelines (Baccarani et al. Blood 2013 122:872-884). Results: From March 2016 until January 2017, 30 patients were enrolled. Median age was 47 years (22 to 84). Sokal risk was low in 17 patients, intermediate in 10, and high in 3. Response data are shown below. Among 7 patients not in CCyR at 3 months by FISH (% FISH + 3, 3.5, 4.5, 5.5, 7, 9 and 83%), the respective BCR-ABL transcripts (IS) were 0.49, 0.08, 0.1, 0.09, 0.60, 0.69 and 9.2%. Thus, 6/7 patients with FISH + disease at 3 months had BCR-ABL transcripts (IS) < 1%, and 17/18 patients evaluable at 3 months had BCR-ABL transcripts (IS) < 1% (equivalent to CCyR). Significant myelosuppression requiring treatment interruption occurred in only 1 patient. No patients so far had pleural effusions requiring intervention. To date, there have been no dose modifications. Conclusions: Dasatinib 50mg daily is active and well-tolerated in newly diagnosed CML-CP. It should be further explored as a new potential dose-schedule standard-of-care in CML. [Table: see text]