A phase II study of oral idarubicin as a treatment for metastatic hormone-refractory prostate carcinoma with special focus on prostate specific antigen doubling time. Swiss Group for Clinical Cancer Research, Berne, Switzerland

Abstract

Background: Treatment of hormone-refractory prostate carcinoma with chemotherapy is purely palliative, and reported response rates have been low. At the time this study was conducted, there was an urgent need for a trial using potentially efficacious drugs, with quality of life (QL), and serial prostate specific antigen (PSA) behavior as endpoints.

Methods: In this Swiss multicenter Phase II study, 30 patients were enrolled to receive oral idarubicin. Patients were administered 35 mg idarubicin on Days 1 and 8 of each cycle, and treatment was repeated every 3 weeks. Assessment was based on response rates, sequential PSA measurements in serum, toxicity, and selected aspects of QL.

Results: Twenty-six of 30 patients were evaluable for response, and none of them achieved a response. Three patients had stable disease as their best response, and their PSA levels also remained stable. In all other patients, PSA increased exponentially over time; the median PSA doubling time was 2.1 months (mean, 2.6; range, 0.7-6.1). Toxicity was minimal and consisted mainly of myelosuppression and nausea/vomiting. QL did not change significantly during therapy with regard to general well-being, fatigue, or nausea/vomiting. However, there were improvements in patient-rated and physician-rated pain.

Conclusions: At the dose and schedule used in this study, oral idarubicin showed only minimal efficacy against hormone-refractory prostate carcinoma. In patients who did not respond, PSA doubling times were similar to those in patients who relapsed while receiving only antiandrogen therapy. In future clinical trials, QL and serial PSA behavior should be included in analysis.