Phase II study of paclitaxel and vinorelbine (Pacl-Vin) in hormone-refractory metastatic prostate cancer: double tubulin targeting

Abstract

BACKGROUND: Androgen ablation is the standard treatment for advanced prostate cancer. However, most patients will eventually develop progressive hormone-refractory prostate cancer (HRPC). The aim of the Pacl-Vin study was to determine the efficacy and safety of paclitaxel in combination with vinorelbine in patients with HRPC, following from a phase I trial. METHODS: Thirty castrate patients with progressive, metastatic prostate cancer were enrolled. Patients were treated with paclitaxel 40 mg/m2, vinorelbine 20 mg/m2 intravenously on day 1 and day 8 of a 21-day cycle. RESULTS: Two patients demonstrated a partial response and seven patients had stable disease from a cohort of 10 patients with measurable disease. Of 30 patients assessable for prostate-specific antigen (PSA) response, 19 showed stable disease, which was maintained for at least 4 weeks, while six (20%) experienced>or=50% decline in PSA levels. Median overall survival was 7.3 months (interquartile range (IQR): 4.7-9.9 months). Median progression-free survival was 3.3 months (IQR: 2.5-7.0 months). Improvement in quality of life measures was noted after three cycles of therapy. Grade 3 and 4 toxicities were: neutropenia 8%, febrile neutropenia 4%, infection 2%, anaemia 3%, lethargy 1% and somnolescence 1%. One patient died as a result of neutropenic sepsis. CONCLUSION: In a poor prognostic cohort of patients paclitaxel and vinorelbine is a tolerable regimen, with a 20% PSA and objective response rate. The majority of patients achieved PSA stability. Furthermore, quality of life parameters, such as pain, were improved. However, the low level of activity of this regimen precludes its further testing.