Outcomes Following Abiraterone versus Enzalutamide for Prostate Cancer: A Scoping Review

SIMPLE SUMMARY: Abiraterone acetate and enzalutamide are novel therapies used in advanced prostate cancer. However, their outcomes and toxicities may differ based on patient–specific factors. Understanding these differences may allow clinicians to make personalized treatment decisions based on individual patients. Because clinical trials do not represent the real-world population, this study used a formal protocol to review and collate smaller, real-world samples, aiming to explain the differences in outcomes following administration of these two drugs. We found that enzalutamide typically has improved cancer response and overall survival. Enzalutamide more commonly causes neurological side effects and fatigue, while abiraterone acetate has cardiovascular complications. Abiraterone acetate leads to increased costs and healthcare needs, including hospitalizations and emergency room visits. Ultimately, this study demonstrates significant differences in patient experiences and outcomes following abiraterone acetate versus enzalutamide. Clinicians may use this information to inform their treatment choice on a patient-specific basis. ABSTRACT: Abiraterone acetate (AA) and enzalutamide (ENZ) are commonly used for metastatic prostate cancer. It is unclear how their outcomes and toxicities vary with patient-specific factors because clinical trials typically exclude patients with significant comorbidities. This study aims to fill this knowledge gap and facilitate informed treatment decision making. A registered protocol utilizing PRISMA scoping review methodology was utilized to identify real-world studies. Of 433 non-duplicated publications, 23 were selected by three independent reviewers. ENZ offered a faster and more frequent biochemical response (30–50% vs. 70–75%), slowed progression (HR 0.66; 95% CI 0.50–0.88), and improved overall survival versus AA. ENZ was associated with more fatigue and neurological adverse effects. Conversely, AA increased risk of cardiovascular- (HR 1.82; 95% CI 1.09–3.05) and heart failure-related (HR 2.88; 95% CI 1.09–7.63) hospitalizations. Ultimately, AA was associated with increased length of hospital stay, emergency department visits, and hospitalizations (HR 1.26; 95% CI 1.04–1.53). Accordingly, total costs were higher for AA, although pharmacy costs alone were higher for ENZ. Existing data suggest that AA and ENZ have important differences in outcomes including toxicities, response, disease progression, and survival. Additionally, adherence, healthcare utilization, and costs differ. Further investigation is warranted to inform treatment decisions which optimize patient outcomes.