ATLANTA, June 3 /PRNewswire-FirstCall/ -- Bristol-Myers Squibb Company today presented interim data from a randomized Phase II study of the investigational compound dasatinib (140 mg/day) or imatinib (800 mg/day) in patients with chronic-phase chronic myelogenous leukemia (CML) resistant to imatinib (less than or equal to 600 mg/day). The data were presented today at the 42nd Annual Meeting of the American Society of Clinical Oncology (ASCO).
This multi-center trial accrued 150 chronic-phase CML patients resistant to imatinib. Patients were randomized in a 2:1 ratio to either start treatment with dasatinib at 140 mg/day (n=101) or receive increased imatinib doses of 800 mg/day (n=49).
The primary endpoint of the study was major cytogenetic response at 12 weeks. Major cytogenetic response is defined as complete (no signs of Philadelphia chromosome positive [Ph+] cells in the bone marrow) plus partial (less than 35% of Ph+ cells in the bone marrow) cytogenetic responses. Thirty-five percent (35/101) of patients in the dasatinib arm experienced a major cytogenetic response (21% complete). Twenty-nine percent (14/49) of patients in the imatinib arm experienced a major cytogenetic response (8% complete).
Crossover to the alternate therapy was permitted in the event of disease progression or intolerable toxicity. Six percent (6/101) of dasatinib-treated patients and 73% (36/49) of imatinib-treated patients crossed over to the opposite treatment arm. At the time of this analysis, 19 of the patients who crossed over from imatinib to dasatinib were evaluable for response; eight of these patients achieved a major cytogenetic response (four complete). None of the four evaluable patients who crossed over from dasatinib to imatinib achieved a major cytogenetic response.
Important non-hematologic adverse events in the dasatinib arm included diarrhea (26%), fluid retention (25%), nausea (21%), bleeding (17%), and vomiting (6%). Important non-hematologic adverse events in the imatinib arm included fluid retention (43%), nausea (31%), diarrhea (29%), vomiting (22%), and bleeding (8%). Grade 3 or 4 cytopenias observed in the dasatinib arm included low absolute neutrophil white blood cells (58%), platelets (54%), and hemoglobin (9%). Grade 3 or 4 cytopenias observed in the imatinib arm included low absolute neutrophil white blood cells (38%), platelets (14%), and hemoglobin (8%).
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