Retrospective cohort study of abiraterone or enzalutamide for metastatic castration-sensitive prostate cancer

Enzalutamide or abiraterone, combined with androgen-deprivation therapy, is standard of care for metastatic castration-sensitive prostate cancer (mCSPC). A US-wide, retrospective cohort study compared outcomes of these two drugs. The study included patients with mCSPC initiating enzalutamide (n=1803) or abiraterone (n=3332) between 2020 and 2023 within the Veterans Affairs healthcare system. The median age was 74.3 years; 58% were non-Hispanic White, 28.2% were non-Hispanic Black, and 5.6% were Hispanic. The median follow-up was 18.74 months for abiraterone and 24.76 months for enzalutamide. Inverse probability of treatment weighting was used to balance baseline characteristics. Outcomes were similar overall: for overall survival the 3-year restricted mean survival time (RMST) difference was 0.72 months (95% CI -0.06 to 1.50), for time to treatment switch or death the 3-year RMST difference was 0.53 months (-0.45 to 1.51), and for prostate cancer-specific survival the 1-year RMST difference was -0.12 months (-0.35 to 0.11). In subgroup analysis, enzalutamide was associated with improved overall survival among patients aged 75 years and older (3-year RMST difference 1.65 months; 95% CI 0.41 to 2.89) but not among younger patients (0.13 months; -0.86 to 1.11). The authors conclude that enzalutamide and abiraterone yielded comparable outcomes, although a small but statistically significant overall survival benefit was observed for enzalutamide among patients aged ≥ 75 years.