Maximal androgen blockade for patients with metastatic prostate cancer: outcome of a controlled trial of bicalutamide versus flutamide, each in combination with luteinizing hormone-releasing hormone analogue therapy. Casodex Combination Study Group

Abstract

Objectives: To review the outcome of therapy with maximal androgen blockade and compare the efficacy and safety of bicalutamide and flutamide, each used in combination with luteinizing hormone-releasing hormone analogue (LHRH-A) therapy, in patients with untreated metastatic (Stage D2) prostate cancer.

Methods: Randomized, double-blind (for antiandrogen therapy), multicenter study with a 2 x 2 factorial design. A total of 813 patients were allocated 1:1 to bicalutamide (50 mg once daily) or flutamide (250 mg three times daily), plus 2:1 to goserelin acetate (3.6 mg every 28 days) or leuprolide acetate (7.5 mg every 28 days).

Results: At the time of analysis (median follow-up, 49 weeks), bicalutamide plus LHRH-A was associated with a statistically significant improvement in time-to-treatment failure, the primary endpoint, when compared with flutamide plus LHRH-A. The results with longer follow-up (median, 95 weeks) support previous findings of an improved time-to-treatment failure with bicalutamide plus LHRH-A; however, the difference between groups was not statistically significant. A treatment failure endpoint was reached by 68% of patients in the bicalutamide plus LHRH-A group, compared with 72% of patients in the flutamide plus LHRH-A group. The hazard ratio of bicalutamide plus LHRH-A to flutamide plus LHRH-A was 0.87 (95% confidence interval [CI], 0.74-1.03; P = 0.10). The upper one-sided 95% confidence limit for survival was 1.00, meeting the definition for equivalence (< 1.25). With longer follow-up, overall mortality was 34%, with equivalent survival between groups: 32% of patients in the bicalutamide plus LHRH-A group died, compared with 35% in the flutamide plus LHRH-A group. The hazard ratio of bicalutamide plus LHRH-A to flutamide plus LHRH-A was 0.88 (95% CI, 0.69-1.11; P = 0.29). The upper one-sided 95% confidence limit for survival was 1.07, meeting the definition for equivalence (< 1.25). Diarrhea occurred in 24% of patients in the flutamide plus LHRH-A group compared with 10% of patients in the bicalutamide plus LHRH-A group (P < 0.001).

Conclusions: In patients with metastatic prostate cancer, bicalutamide plus LHRH-A is effective and well tolerated. Because of its efficacy and tolerability profile, together with its convenient once-daily dosing formulation, bicalutamide represents a prime candidate for antiandrogen of first choice in combination with LHRH-A therapy in the treatment of men with metastatic prostate cancer.