Once Daily Leukemia Drug Dose Effective, Less Toxic

June 12, 2008

Dasatinib, a BCR-ABL inhibitor considerably more potent than imatinib, has similar efficacy but less toxicity at a dose of 100 mg once a day compared with the approved 70 mg twice a day in patients with chronic-phase chronic myelogenous leukemia who have failed imatinib treatment, according to study findings published online June 9 in the Journal of Clinical Oncology.

THURSDAY, June 12 (HealthDay News) -- Dasatinib, a BCR-ABL inhibitor considerably more potent than imatinib, has similar efficacy but less toxicity at a dose of 100 mg once a day compared with the approved 70 mg twice a day in patients with chronic-phase chronic myelogenous leukemia who have failed imatinib treatment, according to study findings published online June 9 in the Journal of Clinical Oncology.

In an open-label phase III trial, Neil P. Shah, M.D., Ph.D., from the University of California San Francisco, and colleagues randomly assigned 670 patients with chronic-phase chronic myelogenous leukemia who had failed imatinib treatment (due to resistance or intolerance) to dasatinib treatment at 100 mg once a day, 50 mg twice a day, 140 mg once a day, or 70 mg twice a day.

After a minimum follow-up of six months, the researchers found that all four groups had similar hematologic response rates (complete, 86 to 92 percent), cytogenetic response rates (major, 54 to 59 percent; complete, 41 to 45 percent), time to and duration of cytogenetic response, and progression-free survival rates (8 to 11 percent of patients had progression or died). However, there was significantly less pleural effusion and grade 3 to 4 thrombocytopenia, and less need for dose interruption, reduction or discontinuation for the 100 mg once-daily dose compared with the approved 70 mg twice-a-day dosing.

"Dasatinib 100 mg once daily retains the efficacy of 70 mg twice daily with less toxicity," Shah and colleagues conclude. "Intermittent target inhibition with tyrosine kinase inhibitors may preserve efficacy and reduce adverse events."

Several of the study authors have financial ties to Bristol-Myers Squibb and the company provided funding for the study.

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