Efficacy and safety of androgen deprivation therapy after switching from monthly leuprolide to monthly degarelix in patients with prostate cancer

Summary Objectives:  To evaluate whether switching prostate cancer (PCa) patients from leuprolide to degarelix is associated with any change in the efficacy of testosterone suppression or safety profile during the first 3 months. Methods:  Participants were 134 patients with histologically confirmed PCa who had completed 1 year of treatment with leuprolide 7.5 mg monthly before being switched to degarelix. These patients were re‐randomised for the extension trial to receive a starting dose of 240 mg degarelix followed by monthly maintenance doses of either 80 ( n  = 69) or 160 mg ( n  = 65). For efficacy assessment, serum testosterone, prostate‐specific antigen (PSA), luteinising hormone (LH) and follicle‐stimulating hormone (FSH) levels measured at days 3, 7, 14, 28, 56 and 84 assessed whether treatment efficacy is sustained. Safety and tolerability assessments included adverse events (AEs), physical examinations, electrocardiograms and clinically significant changes in laboratory safety parameters. Results:  Serum testosterone, LH, and PSA levels were all sustained in both treatment arms during the observation period. Interestingly, FSH levels were further decreased by 30% following the switch to degarelix. With the exception of injection site reactions, the overall prevalence and pattern of AEs during the first 3 months after the switch was comparable to that during the last 3 months leuprolide treatment in the main trial. There were five (4%) patients discontinued to treatment‐related AEs including injection site pain ( n  = 3) and fatigue ( n  = 2). Conclusions:  This 3‐month analysis indicates that patients with prostate cancer can be safely switched from leuprolide to degarelix treatment with sustained efficacy as measured by biochemical markers.