Dasatinib (SPRYCEL®) 50mg or 70mg BID Versus 100mg or 140mg QD in Patients with Chronic Myeloid Leukemia in Chronic Phase (CML-CP) Resistant or Intolerant to Imatinib: Results of the CA180-034 Study.

Phase II studies of dasatinib (SPRYCEL^®, formerly BMS-354825), an oral multi-targeted kinase inhibitor of BCR-ABL and SRC kinases, have demonstrated the efficacy and safety of a 70mg twice daily (BID) dose in CML-CP patients (pts) with resistance or intolerance to imatinib (im). A phase I trial of dasatinib (N Engl J Med 2006;354:2531–41) had shown complete hematologic responses (CHR) and major cytogenetic responses (MCyR) at total daily doses of 100mg and 140mg daily in both BID and once daily (QD) schedule in CML-CP pts. The primary objective of the present study was to compare 6 month (mo) cytogenetic response (CyR) rates among the BID and QD regimens of dasatinib. Secondary objectives included estimating differences in CyR rates between the total daily doses of 100 and 140mg, and safety across the arms to optimize the dose and schedule of the drug. Dasatinib was administered according to one of 4 arms: 50mg BID, 70mg BID, 100mg QD or 140mg QD. Dose escalation to 90mg BID or 180mg QD and reduction to 40mg BID or 80mg QD were allowed for inadequate response or adverse events (AEs), respectively. Evaluation included complete blood counts every 2 weeks x 6 then every 3 mo; bone marrow cytogenetics at mo 3, 6 and then every 6 mo; and qPCR monthly x 3 then every 3 mo. A total of 670 pts were randomized and 663 treated in 139 worldwide sites from July 2005 to March 2006. Median age was 55 years and 47% were male. The median time from CML diagnosis to randomization was 54 mo. All pts received prior im: <1% had <400mg/d, 66% had 400–600mg/d and 34% had >600mg/d. The best previous response to im was CHR in 83% and MCyR in 42%. Prior treatment for CML included interferon alpha in 52%, chemotherapy in 27% and stem cell transplantation in 5% of cases. With a median follow-up of 3 mo, the overall CHR rate for the entire population is 80% and MCyR rate is 37% as of August 2006. 44% of pts required a dose interruption; 25% were due to hematologic toxicity and 14% due to non-hematologic toxicity; 28% required a dose reduction of which 13% were due to hematologic toxicity and 6% due to non-hematologic toxicity; the remainder of dose interruptions and reductions were due to other (including dosing error) or unknown reasons. 3% of pts had a dose escalation typically due to lack of CHR after 3 mo or no decrease in WBC after 1 mo. 601 (90%) pts remain on the trial with the majority of discontinuations for disease progression or study drug toxicity. Grade 3–4 neutropenia and thrombocytopenia occurred in 35% and 30% of pts, respectively. AEs considered drug related by the investigators included headache 24%, diarrhea 20%, nausea 16%, fatigue 12%, rash 11%, edema 10%, dyspnea 7%, pleural effusion 7%, myalgia 7%, arthralgia 5%, anorexia 4%, pneumonia 1%, and gastrointestinal hemorrhage 1%. Rare AEs that were considered drug-related by the investigators included congestive heart failure in 4 pts, and cardiac dysfunction, pulmonary hypertension, pulmonary edema and pericardial effusion in 3 pts each. Other AEs regardless of relationship to study drug included grade 3–4 creatinine elevation in 4%, grade 3–4 transaminase elevation in <1%, and grade 3–4 hypocalcemia in 1% of pts. Updated safety and efficacy data on all treatment groups with a minimum of 6-months of follow-up will be presented at the meeting.