The Safety of Abiraterone Acetate in Patients with Metastatic Castration-Resistant Prostate Cancer: An...

Background/objectives: Multiple systemic treatments are available for metastatic castration-resistant prostate cancer (mCRPC), with unclear safety profiles. This study seeks to describe the safety determined in randomized clinical trials of a systemic treatment for mCRPC and whether safety differs by age. Methods: We utilized individual patient data from industry-funded phase 2/3 trials in mCRPC on abiraterone acetate (AA). Vivli, a clinical trial repository site, was used. One investigator independently performed screening. Relative effects of treatment were assessed with frequencies and odds of serious adverse events (SAEs). The Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline was used. Subgroup analysis measured odds of SAEs as modified by age. Results: We identified 14 trials with 4296 patients. The median age of participants was 69 years. Nearly all participants experienced at least one adverse event (98.4% abiraterone, 97.3% standard of care [SOC]). More serious adverse events (grade 3 or 4) and deaths (grade 5) occurred in those receiving SOC (71.8%) compared to abiraterone (64.1%). The most frequent adverse event category was "Musculoskeletal and Connective Tissue Disorders". The most frequent event types included anemia, back pain, hypertension, fatigue, hypokalemia, and bone pain. The odds of all events were lower in those receiving abiraterone compared to SOC. Odds of a serious musculoskeletal event were lower in older subjects by 22% (OR 0.78; 95% CI 0.63, 0.96). Conclusions: In this IPD meta-analysis, abiraterone acetate provides no greater risk of SAE in those receiving abiraterone than those receiving SOCs. Patients in the RCTs are younger and healthier than those in the general population; consequently, the results of RCTS might not be applied to the general population, especially those under-represented in the RCTs. There is a need to further evaluate abiraterone-related fractures and neuromuscular toxicities (NMTs) as key outcomes to gain insight into risk factors related to these adverse events. A real-world prospective study is warranted to examine the overall risks and benefits associated with treatment.