Abiraterone vs Enzalutamide Among US Veterans With Metastatic Hormone-Sensitive Prostate Cancer

Area of Science:

• Oncology
• Urology
• Pharmacology

Background:

• First-line hormonal therapy choice for metastatic hormone-sensitive prostate cancer (mHSPC) lacks comparative data between abiraterone and enzalutamide.
• Clinical practice often relies on comorbidities or physician preference due to limited trial and real-world evidence, particularly for African American patients.

Purpose of the Study:

• To compare clinical outcomes, including tumor growth rates (g-rates) and overall survival (OS), in patients with mHSPC treated with abiraterone acetate versus enzalutamide.

Main Methods:

• A retrospective cohort study analyzed mHSPC patients in the US Veterans Affairs Health Care system initiating abiraterone or enzalutamide (July 2017-April 2023).
• Outcomes measured included g-rates (estimated from prostate-specific antigen [PSA] values) and OS.
• Two matching analyses were performed: inverse probability weighting (IPW) and 1:1 exact matching.

Main Results:

• A total of 1569 patients were included (1258 on abiraterone, 311 on enzalutamide), with 25.0% and 27.0% being African American, respectively.
• IPW and 1:1 matched analyses revealed comparable median OS and g-rates between abiraterone and enzalutamide.
• No statistically significant differences in outcomes were observed based on race (including African American subgroups), cardiovascular disease, Gleason score, or baseline PSA levels.

Conclusions:

• Abiraterone and enzalutamide demonstrate comparable efficacy in the first-line mHSPC setting.
• Treatment choice between abiraterone and enzalutamide does not appear to significantly impact survival or tumor growth rates based on race, comorbidities, or specific prostate cancer features.