Phase II study of the oral cyclophosphamide and oral etoposide combination in hormone-refractory prostate carcinoma patients.

Abstract

Hormonotherapy temporarily controls symptoms in 80% of patients with metastatic prostate carcinoma. Once progression occurs, no consensus exists on further therapy. Oral etoposide (VP-16) has shown clinical efficacy in advanced small cell lung carcinoma, breast cancer, germ cell tumors, and lymphomas, A synergistic effect between etoposide and alkylating agents such as estramustine was recently reported. We began a prospective Phase II study of an oral combination of cyclophosphamide (CPM) and VP-16 in patients with hormone-refractory [correction of refactory] prostate carcinoma (HRPC). Patients were orally treated with CPM (100 mg/day) and VP-16 (50 mg/day) for 14 days every 28 days. Therapy continued until there was evidence of disease progression. From November, 1992, to February, 1995, 20 patients with HRPC were entered into the study. Patients were eligible if they had an ECOG performance status (PS) of 0 to 2. All of the patients presented with bone metastasis, and 70% presented with bone pain. Seventy-five percent had failed at least two hormonal manipulations. The mean duration of treatment was 5 months (range 2-12). Performance status improved in 26% of the patients, and bone pain was relieved in 71%. An objective response was defined as a decrease of 50% or more in the prostate-specific antigen (PSA) level. One patient demonstrated a complete response, and six patients had partial responses assessed by PSA plasma levels (objective response rate: 35%). The mean duration of response was 8 +/- 6 months (range: 2-24). Median survival was 11 months. Toxicities were minimal. The combination of oral CPM and VP-16 may be an active and well tolerated regimen for patients with HRPC.