Abstract

Abstract Therapeutic options for chronic myelogenous leukemia (CML) resistant to 400 to 600 mg imatinib are limited. Escalating imatinib doses may overcome resistance. Dasatinib, a significantly more potent inhibitor of BCR-ABL, is safe and effective in this population. Patients with imatinib-resistant chronic-phase (CP) CML were randomized 2:1 to 140 mg dasatinib (n = 101) or 800 mg imatinib (n = 49). With a median follow up of 15 months, complete hematologic responses were observed in 93% and 82% of patients receiving dasatinib and high-dose imatinib (P = .034), respectively. Dasatinib resulted in higher major cytogenetic response rates (52%) than high-dose imatinib (33%) (P = .023); this included complete cytogenetic response in 40% and 16% (P = .004). Major molecular responses were also more frequent with dasatinib (16% versus 4%; P = 0.038). Treatment failure (hazard ratio [HR], 0.16; P < .001) and progression-free survival (HR, 0.14; P < .001) both favored dasatinib. Superficial edema (42% versus 15%) and fluid retention (45% versus 30%) were more prevalent with imatinib; pleural effusion was more common with dasatinib (17% versus 0%). Grade 3 to 4 nonhematologic toxicity was minimal. Cytopenias were more frequent and severe with dasatinib. Dasatinib represents a safe and effective therapy for CP-CML resistant to conventional imatinib doses with improved cytogenetic and molecular response rates and progression-free survival relative to high-dose imatinib.