Comparative effectiveness and safety of enzalutamide versus abiraterone in patients with metastatic castration-resistant prostate cancer: a nationwide registry-based cohort study from Taiwan.

PURPOSE: The real-world effectiveness and safety of abiraterone or enzalutamide in the Asian population with metastatic castration-resistant prostate cancer (mCRPC) remains unclear.

METHODS

Using the Taiwan National Health Insurance Research Database, we identified a cohort of 3056 patients diagnosed with mCRPC receiving abiraterone or enzalutamide from January 1, 2017 through April 30, 2020, followed until December 31, 2021. We applied inverse probability of treatment weighting (IPTW) to balance the treatment groups and compare outcomes between the two treatment groups. Effectiveness outcomes included all-cause death, prostate cancer-related death, and treatment failure. Safety outcomes included major adverse CV events (MACE), fractures, and venous thromboembolism (VTE).

RESULTS

Enzalutamide use was associated with superior overall survival (hazard ratio 0.88, 95% confidence interval [CI] 0.82-0.96) compared with abiraterone use, which was majorly contributed from pre-docetaxel use (HR 0.89, 95% CI 0.81-0.98) but not post-docetaxel use (HR = 0.93, 95% CI 0.80-1.07). The median overall survival of pre-docetaxel abiraterone and enzalutamide was 36.1 and 39.9 months, respectively. In contrast, the median overall survival of post-docetaxel abiraterone and enzalutamide was 22.5 and 24.2 months, respectively. In terms of safety outcomes, enzalutamide use was significantly associated with lower VTE events compared with abiraterone use, but there was no difference in MACE or fracture risk between enzalutamide and abiraterone.

CONCLUSIONS

We demonstrated the survival of enzalutamide and abiraterone use in Taiwanese patients with mCRPC is consistent with pivotal trials. The higher VTE risk with abiraterone use should be monitored.