Oral estramustine and cyclophosphamide in patients with metastatic hormone refractory prostate carcinoma: a phase II study

BACKGROUND: Nearly all cases of metastatic prostate carcinoma progress, after hormonal ablation, to a hormone refractory status. To the authors' knowledge no standard chemotherapy for patients with hormone refractory prostate carcinoma (HRPC) exists. In a prospective study, the efficacy and toxicity of an oral combination of estramustine and cyclophosphamide were evaluated. METHODS: Between March 1996 and April 1998, 32 consecutive patients (median age 74 years; range, 53-84 years) with metastatic HRPC were treated with oral estramustine (10 mg/kg/day) and oral cyclophosphamide (2 mg/kg/day) for 14 days every 28 days. Inclusion criteria were previous complete androgen blockade, antiandrogen withdrawal evaluation, and clinical or biochemical disease progression. Response assessment was based on a decrease > or =50% in the prostate specific antigen (PSA) level associated with improvement (or no worsening) in Eastern Cooperative Oncology Group (ECOG) performance status (PS) and relief of bone pain (if present). RESULTS: All patients were evaluable for efficacy and toxicity. PSA levels decreased by at least 50% in 14 patients (43.7%) (95% confidence interval, 26.5-60.9), remained stable in 12 patients (37.5%), and rose in 6 patients (18.8%). ECOG PS was 0 in 5 of 14 patients, improved from 1 to 0 in 7 patients, and remained unchanged in 2 patients. Bone pain, present in 8 of 14 patients, disappeared in 7 and was partially relieved in 1. The median duration of response was 30 weeks (range, 8-88+ weeks). An objective partial response was obtained in two cases. Toxicity was mild and mainly gastrointestinal (World Health Organization [WHO] Grade 1). No cases of WHO Grade 3-4 hematologic toxicity occurred. CONCLUSIONS: The oral combination of estramustine and cyclophosphamide appears to be safe and effective in patients with HRPC. In responding patients its use shows a clinical benefit in terms of improvement of ECOG PS and pain control.