Major adverse cardiovascular events of enzalutamide versus abiraterone in prostate cancer: a retrospective cohort study

Background: While the cardiovascular risks of androgen receptor pathway inhibitors have been studied, they were seldom compared directly. This study compares the risks of major adverse cardiovascular events (MACE) between enzalutamide and abiraterone among prostate cancer (PCa) patients.Methods: Adult PCa patients receiving either enzalutamide or abiraterone in addition to androgen deprivation therapy in Hong Kong between 1 December 1999 and 31 March 2021 were identified in this retrospective cohort study. Patients who switched between enzalutamide and abiraterone, initiated abiraterone used without steroids, or experienced prior cardiac events were excluded. Patients were followed-up until 30 September 2021. The primary outcomes were MACE, a composite of stroke, myocardial infarction (MI), Heart failure (HF), or all-cause mortality and a composite of adverse cardiovascular events (CACE) not including all-cause mortality. The secondary outcomes were individual components of MACE. Inverse probability treatment weighting was used to balance covariates between treatment groups.Results: In total, 1015 patients were analyzed (456 enzalutamide users and 559 abiraterone users; mean age 70.6 +/- 8.8 years old) over a median follow-up duration of 11.3 (IQR: 5.3-21.3) months. Enzalutamide users had significantly lower risks of 4P-MACE (weighted hazard ratio (wHR) 0.71 [95% confidence interval (CI) 0.59-0.86], p < 0.001) and CACE (wHR 0.63 [95% CI: 0.42-0.96], p = 0.031), which remained consistent in multivariable analysis. Such an association may be stronger in patients aged >= 65 years or without diabetes mellitus and was independent of bilateral orchidectomy. Enzalutamide users also had significantly lower risks of MI (wHR 0.57 [95% CI: 0.33-0.97], p = 0.040) and all-cause mortality (wHR 0.71 [95% CI: 0.59-0.85], p < 0.001).Conclusion: Enzalutamide was associated with lower cardiovascular risks than abiraterone in PCa patients.