Long-term use and risk of major adverse cardiac events: Comparing enzalutamide and abiraterone in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer

This is a retrospective cohort study by analyzing a multi-institutional electronic medical records database in Taiwan to compare long-term effectiveness and risk of major adverse cardiac events (MACE) in chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) patients treated with enzalutamide (ENZ) or abiraterone (AA). Patients aged 20 years and older and newly receiving androgen receptor targeted therapies ENZ or AA from September 2016 to December 2019 were included. We followed patients from initiation of therapies to the occurrence of outcomes (prostate-specific antigen (PSA) response rate, PSA progression free survival (PFS), overall survival (OS), and MACE), death, the last clinical visit, or December 31, 2020. We performed multivariable Cox proportional hazard models to compare ENZ and AA groups for the measured outcomes. A total of 363 patients treated with either ENZ (n = 157) or AA (n = 206) were identified. The analysis found a significantly higher proportion of patients with a PSA response rate higher than 50% among those receiving ENZ than among those receiving AA (ENZ vs AA: 75.80% vs 63.59%, P =.01). However, there was no significant difference in PSA PFS (adjusted hazard ratio: 0.86; 95% CI 0.63-1.17) and OS (0.68: 0.41-1.14) between the use of ENZ and AA in chemotherapy-naïve mCRPC patients. Regarding the cardiovascular (CV) safety outcome, there was a significantly lower risk of MACE in patients receiving ENZ, compared to patients receiving AA (0.20: 0.07-0.55). The findings suggest that enzalutamide may be more efficacious for PSA response and suitable for chemotherapy-naïve mCRPC patients with high CV risk profile.