Globally, androgen deprivation therapy (ADT) strategies for both prostate-specific antigen (PSA) recurrence and metastatic prostate cancer (PCa) vary significantly. Data suggest that PSA progression free-survival (PSA-PFS) may predict overall survival in PCa patients (pts). We compare PSA-PFS with a GnRH antagonist (degarelix) and LHRH agonists (leuprolide, goserelin) in metastatic or high risk PCa pts in the Americas, Europe and Asia.
Data were pooled from two pivotal phase 3 randomized trials of men with PCa where ADT was indicated for pts with metastatic disease or those with PSA relapse deemed at high risk. Metastatic PCa was defined by baseline TNM staging (M1). High risk PCa was defined as baseline PSA >20 ng/mL or Gleason score 8–10. Pts in the Americas (n = 60), Europe (n = 97) and China (n = 224) were randomized to receive degarelix (n = 193), or LHRH agonist (n = 188). PSA-PFS was defined as death from any cause or PSA recurrence (two consecutive increases ≥50% [≥2 weeks apart] and ≥5 ng/mL increase from nadir). Unadjusted Kaplan-Meier analyses (log-rank p-value) and Cox-proportional hazard models (Wald Chi-square p-value) were used (stratified by baseline PSA categories, and adjusted for treatment, PCa stage, age and region) to assess treatment differences in PSA-PFS.
PSA-PFS was significantly improved in the degarelix group among metastatic or high risk pts (p = 0.011). Region did not influence difference between antagonist and agonist in PSA-PFS (treatment-by-region interaction p = 0.884), however, Chinese (HR = 0.48 [95% CI: 0.31–0.74]) and American (HR = 0.26 [95%CI: 0.10–0.68]) pts had lower risk for PSA-PFS compared to European pts. There was a lower hazard for PSA-PFS with degarelix across all regions when stratifying for PSA (and adjusting for confounders); HR = 0.67 (95%CI: 0.44–1.01), p = 0.053.
Improved PSA-PFS was shown in pts treated with degarelix vs LHRH agonists in metastatic or high risk PCa pts irrespective of region. These results suggest delay of disease progression with initial use of a GnRH antagonist as compared with LHRH agonists across global regions.
Clinical trial identification
Legal entity responsible for the study
N. Shore: Consultant/advisor for AbbVie, Ferring Pharmaceuticals, Takeda Pharmaceutical, Tolmar
Z. Bosnyak, A. Malmberg, P-A. Abrahamsson: Employee of Ferring Pharmaceuticals.
M. Gittelman, L-P. Xie: The author declares no conflict of interest.