Phase II trial of cyclophosphamide, vincristine, and dexamethasone in the treatment of androgen‐independent prostate carcinoma

BACKGROUND: In this Phase II study, the authors assessed the toxicity and anti-tumor activity of a combination of oral cyclophosphamide, oral low-dose dexamethasone, and intravenous vincristine (CVD) in patients with metastatic androgen-independent prostate carcinoma (AI-PCa). METHODS: Patients with histologic proof of adenocarcinoma of the prostate progressing despite adequate hormonal therapy and adequate organ function were treated with oral cyclophosphamide, 250 mg/daily (Days 1-14); intravenous vincristine, 1 mg daily (Days 1, 8, 15); and oral dexamethasone, 0.75 mg twice a day (Days 1-14) in 28-day cycles. Study endpoints were toxicity, rate of prostate specific antigen (PSA) decline > 50%, and/or measurable disease response. RESULTS: Fifty-two (95%) of 55 registered patients were evaluable. The majority (65%) of patients had received prior chemotherapy. The median number of treatment cycles given was two (range, one-seven cycles). Twenty-nine percent of the patients were found to have a > 50% decline in PSA level compared with baseline levels, and 25% of the patients with bidimensionally measurable soft-tissue or visceral disease were found to have a partial response. The median progression-free survival duration was 10 weeks, and the median overall survival duration was 10.6 months. There were no thromboembolic events, and hematologic and nonhematologic toxicity was minimal. CONCLUSIONS: CVD was found to be an active and well-tolerated regimen for AI-PCa. The low toxicity profile makes CVD a useful treatment option for patients with significant comorbidities and high risk for treatment-related toxicity, especially thromboembolic events and myelotoxicity.