Long-term Tolerability and Efficacy of Degarelix: 5-Year Results From a Phase III Extension Trial With a 1-Arm Crossover From Leuprolide to Degarelix

Objective To demonstrate the safety and efficacy of up to 5 years of degarelix treatment and the effects of crossing over from leuprolide to degarelix in the extension phase of a phase III pivotal 1-year trial. Methods Patients receiving degarelix who completed the 1-year trial continued on 80 mg (n = 125) or 160 mg (n = 126) maintenance doses. Patients who received leuprolide were rerandomized to degarelix 240/80 mg (n = 69) or 240/160 mg (n = 65). Safety and tolerability were assessed (primary end point), as well as testosterone and prostate-specific antigen levels and prostate-specific antigen progression–free survival (secondary end points). Results Adverse event frequency was similar between both the groups. Adverse events included initial injection site reactions, hot flushes, and increased weight. Testosterone and prostate-specific antigen values during the extension study were similar to those seen during the 1-year trial in patients who continued on degarelix or crossed over from leuprolide. The prostate-specific antigen progression–free survival hazard rate was decreased significantly after the crossover in the leuprolide to degarelix group (from 0.20 to 0.09; P = .002), whereas in patients who continued on degarelix, the rate did not change significantly. In patients with baseline prostate-specific antigen >20 ng/mL, the same hazard rate change pattern was observed on crossover (from 0.38 to 0.19; P = .019). Conclusion Degarelix was well tolerated; no safety concerns were identified. The significant prostate-specific antigen progression–free survival benefit established for degarelix over leuprolide during year 1 remained consistent at 5 years.