Superior anti-tumor efficacy of bicalutamide 80 mg in combination with a luteinizing hormone-releasing hormone (LHRH) agonist versus LHRH agonist monotherapy as first-line treatment for advanced prostate cancer: Interim results of a randomized study in Japanese patients

Objectives: To evaluate bicalutamide (Casodex) 80 mg as a component of maximum androgen blockade (MAB) in Japanese patients with previously untreated advanced prostate cancer. Methods: 205 patients with previously untreated stage C/D prostate cancer were randomized (1:1) to receive once-daily bicalutamide 80 mg or placebo, each combined with a luteinizing hormone-releasing hormone (LHRH) agonist. Primary study variables were the 12 week prostate-specific antigen (PSA) normalization (i.e. PSA level less than or equal to4 ng/ml) rate, the 12 week overall tumor response rate (proportion with a partial response or better) and the proportion of withdrawals due to adverse drug reactions (ADRs) at follow-up. This interim analysis was undertaken after a minimum of 6 months' follow-up (median 15 months). Results: The 12 week PSA normalization rate was 79.4% for MAB and 38.6% for LHRH agonist monotherapy (P < 0.001). The 12 week overall tumor response rate was 77.5 and 65.3%, respectively (P = 0.063). The withdrawal rate due to ADRs was 8.8% and 10.9%, respectively. There were differences in favor of MAB over monotherapy with respect to time to treatment failure (TTTF) (P = 0.038) and time to progression (TTP) (P = 0.016). There have been too few deaths (n = 10) to analyze survival. The profiles of adverse events and ADRs were broadly similar in the two treatment groups. Conclusion: In Japanese patients with advanced prostate cancer, first-line treatment with bicalutamide 80 mg in combination with an LHRH agonist is superior to LHRH agonist monotherapy in terms of the antitumor response at 12 weeks, and also time to treatment failure and progression, and does not compromise treatment safety. The study is ongoing.