Efficacy of nilutamide as secondary hormonal therapy in androgen-independent prostate cancer (AIPC)

Abstract

4683 Background: Treatment options are limited for patients with androgen independent prostate cancer (AIPC). Secondary hormonal therapy with antiandrogens has advantages, including low toxicity, oral administration and high patient acceptance. We have evaluated the activity of nilutamide as secondary hormonal therapy in patients with AIPC. Methods: Retrospective study was focused on 45 patients with AIPC who were treated with nilutamide as secondary hormonal therapy in two institutions. All patients had a detectable prostate-specific antigen (PSA) at initiation of nilutamide therapy, but were not required to have radiographic evidence of disease. Any number of prior secondary hormonal therapies and prior history of chemotherapy were allowed. The primary endpoint was to determine the % of evaluable patients who had a ≥ 50% decline in PSA. Adverse effects of treatment, and the relationship between baseline patient characteristics, type and duration of previous therapy and response to nilutamide were also assessed. The majority of patients received nilutamide at a dose of 150 mg/day orally. Results: Median patient age at diagnosis was 64 (range 43–88), and median PSA was 17.0 ng/ml (range 2.5–2356). Thirty of 45 evaluable patients (66.6%; 95% CI 51.1–80.0%) experienced PSA decline of any degree after starting nilutamide therapy, and 18 (40%; 95% CI 25.7–55.7%) had a PSA decline ≥ 50% (Responders). Responders had a median time to progression of 4.4 months (range 0.31+-44.7+). Nilutamide responses were seen whether used as 2nd to 5th line hormonal therapy. No differences in response to nilutamide were observed based on clinical stage, type of local therapy, PSA at diagnosis or initiation of nilutamide, or type of prior antiandrogen therapy. Responders were more likely to have received monotherapy with luteinizing hormone releasing hormone agonist or orchiectomy as first line hormonal treatment than non-responders (p=0.02). The most common reversible adverse effects were mild to moderate visual adaptation alterations (20%). Conclusions: Nilutamide appears to be an effective secondary hormonal therapy in patients with AIPC with a mild toxicity profile. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Aventis