A Phase II trial of suramin monthly x 3 for hormone-refractory prostate carcinoma.

Background: The goal of the current study was to determine the prostate-specific antigen (PSA) and objective response rates and the pharmacokinetics associated with a monthly x 3 one-hour infusion of suramin in 58 patients with hormone-refractory prostate carcinoma.

Methods: A PSA response was defined as a > 50% reduction in the PSA level from baseline for at least 3 consecutive evaluations over a minimum of 6 weeks. The suramin dose was 2400 mg/m(2) taken intravenously on Day 1, 1620 mg/m(2) on Day 29, and 1292 mg/m(2) on Day 57. All patients received 0.5 mg dexamethasone twice daily.

Results: Among 56 evaluable patients (median entry PSA level, 229.5 ng/mL), there were 21 PSA responders (37.5%). Among 27 patients with measurable disease, there were 5 responders (4 partial and 1 complete). The median overall survival time was 15.3 months. Grade III fatigue (14.1%) was the predominant toxicity observed. Suramin plasma levels remained high even 3 months after treatment was discontinued. Among the 12 evaluable patients who previously had received chemotherapy, the PSA response rate was 42%; one response was observed among 4 patients with measurable disease, and the median survival was 12 months.

Conclusions: Monthly bolus suramin was well tolerated, reduced PSA levels, and induced objective responses, even in patients who previously had received chemotherapy.