Degarelix was developed as a novel gonadotropin-releasing hormone (GnRH) antagonist, with the aim of counteracting the testosterone surge often experienced with GnRH agonists. Degarelix blocks the GnRH receptors in the pituitary gland, rapidly reducing testosterone production, but the effects last only for a month. It is common practice to switch from degarelix to a GnRH agonist once the testosterone levels are down and stable. Degarelix is safe and effective for the short term, but what about the long term?
Researchers from Osaka City University and Bell Land General Hospital in Japan evaluated 5-year survival and time to castration-resistant prostate cancer (CRPC) in 108 patients with prostate cancer treated with degarelix. In the study, 57 patients were switched from degarelix to a GnRH agonist; 51 continued on degarelix.
Overall 5-year survival was high (89%) but statistically superior in the changed group (97% vs 74%). The 5-year cancer-specific survival also was longer in the changed group (100% vs 85%). Average time to CRCP was comparable in both groups (43 months in the changed group, 35 months in the continued group). The CRPC conversion did not reach the median at the time of data analysis. The median percentage decrease in prostate-specific antigen level for all patients treated with degarelix was 99.7%. The lowered levels were maintained even after switching to GnRH agonists.
The researchers say theirs is the first report of long-term data on degarelix and the first study to report that changing the treatment from a GnRH antagonist to a GnRH agonist did not affect the oncologic outcomes in patients with hormone-sensitive prostate cancer.
Asakawa J, Iguchi T, Tamada S, et al. Basic Clin Androl. 2018;28:9.