A phase 2 study of carboplatin plus docetaxel in men with metastatic hormone-refractory prostate cancer who are refractory to docetaxel

BACKGROUND: Prostate cancer is the second leading cause of cancer mortality among men in the U.S. To the authors' knowledge, there is no proven, effective, second-line therapy for docetaxel-refractory disease. Recent data suggest that platinum salts may be effective when combined with taxanes in metastatic hormone-refractory prostate cancer (HRPC). The authors conducted a phase 2 trial of docetaxel plus carboplatin chemotherapy in this disease setting. METHODS: Eligible men had metastatic HRPC that had progressed during or within 45 days after the completion of docetaxel-based chemotherapy. Patients were treated with intravenous docetaxel at a dose of 60 mg/m(2) plus carboplatin at an area under the curve of 4 once every 21 days until they had either disease progression or unacceptable toxicity. RESULTS: Thirty-four patients were enrolled. Therapy was tolerated reasonably well; Grade 3 leukopenia (graded according to the Common Toxicity Criteria grading system) was the most common adverse event (experienced by 56% of patients), but there was only 1 episode of febrile neutropenia reported. Prostate-specific antigen (PSA) declines > or =50% were noted in 18% of patients, and measurable responses were observed in 14%. The median duration of PSA response was 5.7 months. The median progression-free survival was 3 months, and the median overall survival was 12.4 months. Patients were more likely to respond to the combination if they previously had responded to docetaxel. CONCLUSIONS: In men with HRPC who developed progressive disease during or shortly after treatment with docetaxel, the addition of carboplatin resulted in modest additional activity. Taxane-refractory HRPC is an area of unmet need, and the current trial has provided evidence that platinum chemotherapy may be an important therapeutic option.