Dasatinib Induces Durable Cytogenetic Responses in Patients with Chronic Myelogenous Leukemia in Chronic Phase with Resistance or Intolerance to Imatinib

Dasatinib, a potent inhibitor of BCR-ABL in vitro, is effective for patients with chronic myelogenous leukemia (CML) resistant or intolerant to imatinib. To provide a more definitive assessment of dasatinib in chronic-phase (CP)-CML, we report extended follow-up of a phase II trial, presenting data for the entire patient cohort (N=387). Dasatinib (70 mg) twice daily was administered to patients with imatinib-resistant or -intolerant CP-CML. With median follow-up of 15.2 months (treatment duration, <1-18.4 months), a complete hematologic response was attained or maintained in 91% of patients. A major cytogenetic response (MCyR) was attained or maintained by 59% (52% imatinib resistant and 80% imatinib intolerant); this was complete in 49% of patients (40% imatinib resistant and 75% imatinib intolerant). Of 230 patients achieving an MCyR, 7 experienced disease progression. Fifteen-month progression-free survival was 90% while overall survival was 96%. Grade 3/4 thrombocytopenia and neutropenia were reported in 48 and 49% of patients, respectively. Non-hematologic toxicity (any grade) consisted primarily of diarrhea (37%), headache (32%), fatigue (31%), dyspnea (30%) and pleural effusion (27%). Pleural effusions were classified as grade 3 in 6% of reported events, with no incidence of grade 4. Dasatinib is associated with high response rates in patients with imatinib-resistant or -intolerant CP-CML.