Cardiovascular Safety of Enzalutamide Versus Abiraterone in Patients With mCRPC

Abiraterone and enzalutamide are both common first-line treatment options for patients with metastatic castration-resistant prostate cancer (mCRPC). The drugs have also expanded in use to patients in the castration-sensitive and nonmetastatic settings.

At the 2024 American Society of Clinical Oncology Annual Meeting, Charles Gaber, PhD, MPH, presented a new study comparing the real-world overall survival (OS) rates and risk of major adverse cardiovascular events (MACE) of enzalutamide and abiraterone in older patients with mCRPC.

The comparative observational study involved 5633 patients, with data taken from the Surveillance Epidemiology and End Results-Medicare database. Each patient began treatment with abiraterone or enzalutamide between 2011 and 2017. Measured cofounders were balanced using propensity scores and inverse-probability-of-treatment weighting.

MACE was defined as hospitalization for myocardial infarction, heart failure, ischemic stroke, or transient ischemic attack. Hazard ratios were taken from weighted Cox proportional hazards for mortality and Fine-Gray models for MACE.

The median age of the patient group was 77 years. There were 3720 patients in the abiraterone arm and 1913 in the enzalutamide arm. Compared with patients in the enzalutamide arm, overall survival rates were similar in those who started abiraterone at both 1 year (mortality hazard ratio [HR], 1.05; 95% CI, 0.95-1.17) and 5 years of follow-up (HR, 1.01; 95% CI, 0.95-1.08).

In patients who began abiraterone, the median 1-year risk of MACE was higher than in those who began enzalutamide (5.9 vs 4.5; HR, 1.30; 95% CI, 1.01-1.67). Both treatments displayed similar effects on MACE when considering a 5-year follow-up period after initiation, at 12.2 in the abiraterone arm versus 12.6 in the enzalutamide arm.

Abiraterone and enzalutamide had similar comparative efficacy and cardiovascular safety, although a short-term increase in MACE was seen in patients in the abiraterone arm. Cardiovascular risk and cancer prognosis should be considered carefully when selecting therapies for patients with mCRPC.