Dasatinib in imatinib-resistant or imatinib-intolerant chronic myeloid leukemia in blast phase after 2 years of follow-up in a phase 3 study: efficacy and tolerability of 140 milligrams once daily and 70 milligrams twice daily.

Background: In a phase 3 study, the authors assessed the effects of dasatinib at doses of 140 mg once daily and 70 mg twice daily in patients who had either chronic myeloid leukemia (CML) in advanced phases or Philadelphia chromosome-positive acute lymphoblastic leukemia and were resistant or intolerant to imatinib. In the current report, the results for patients with CML in blast phase after 2 years of follow-up are reported.

Methods: Patients were stratified according to whether they had CML in myeloid blast phase (MBP-CML) or in lymphoid blast phase (LBP-CML) and were randomized (1:1) within each stratum to receive either oral dasatinib 140 mg once daily or 70 mg twice daily.

Results: In patients with MBP-CML, the major hematologic response rate was 28% for both regimens; and, in patients with LBP-CML, the major hematologic response rate was 42% for once-daily dasatinib and 32% for twice-daily dasatinib. The major cytogenetic response rates were 25% for once-daily dasatinib and 28% for twice-daily dasatinib in patients with MBP-CML, and the respective rates in patients with LBP-CML were 50% and 40%. The overall survival rate at 24 months was 24% for once-daily dasatinib and 28% for twice-daily dasatinib in patients with MBP-CML, and the respective values in patients with LBP-CML were 21% and 16%. Adverse events indicated a trend toward improved tolerability for the once-daily regimen.

Conclusions: The current results suggested that dasatinib 140 mg once daily had similar efficacy and improved tolerability relative to the 70-mg twice-daily regimen in patients with imatinib-resistant, blast phase CML.