GNRH-agonist or antagonist in the treatment of prostate cancer: a comparision based on oncological results

Abstract

On the basis of the trials available, are we ready to consider GnRH antagonists better than agonists? Is there a population of patients who may benefit from antagonists more than agonists?We specifically focused our analysis on the significance of oncological results obtained in phase III trials directly comparing Degarelix with GnRH agonists. Oncological results were evaluated only in 1 trial (CS21) with some subanalysis and they were not the primary endpoints of the study. The follow-up duration was 364 days, and therefore, the number of events (all causes deaths and prostate cancer (PC), Prostate Specific Antigen (PSA), Hazard ratio (HR)-related deaths) was very low in both groups and this aspect strongly reduces the significance of overall survival evaluation. In our opinion, the CS21A open-label extension does not consent to obtain useful clinical data and the design of the study loses the possibility to have a longer randomized comparison between degarelix and agonist. Moreover, the fact that the crossover from leuprolide to degarelix was pre-defined at 12 months and not at agonist failure does not allow to gather data also on the effect of sequential treatment.The answer to the question whether we are ready to consider antagonists better than agonists, based on oncological results, is probably no. We have data in terms of testosterone suppression and PSA control rather than overall survival or clinical progression free survival. A PSA progression-free survival is a secondary endpoint that in our opinion is not sufficient. Large prospective comparative trials with long-term follow-up are needed to clarify this critical clinical question.