Meta-analysis of randomized clinical trials in metastatic castration resistant prostate cancer: Comparison of hypertension, neurological and psychiatric adverse events on enzalutamide and abiraterone acetate plus prednisone treatment

Abstract

Background: Enzalutamide (ENZ) and abiraterone acetate (AA) are oral hormonal agents for the treatment of metastatic castration resistant prostate cancer (mCPRC) patients. Although these two drugs target the androgen signaling pathway, they have different mechanisms of action, with ENZ targeting the androgen receptor1 whilst abiraterone targeting the activity of CYP172.Consequently, they also differ in the nature of their adverse events profile Methods: Following a meta-analysis presented at ASCO GU 20163 on fatigue and cardiovascular adverse events (AEs) a further analysis, using the same methodology, was performed on hypertension, neurological and psychiatric AEs based on a literature search of randomized controlled trials (RCTs) that included AA + prednisone (P) or ENZ. The risk of these AEs was assessed by the overall relative risk of all the RCTs that comply with the inclusion criteria. Summary of incidence, relative-risks (RR), and 95% confidence intervals (CI) were calculated using random-effects or fixed-effects models based on the heterogeneity of included studies. Results: RR for hypertension (all grades) was 2.26 (1.06-4.81) for ENZ and 1.61 (1.30-2.00) for AA + P, for hypertension grade ≥ 3 was 2.52 (1.61-3.95) and 1.72 (0.97-3.06) respectively. The RR for neurological disorders was 1.44 (1.31-1.58) for ENZ and 1.13 (0.99-1.29) for AA + P. RR for psychiatric disorders was 1.43 (1.21-1.69) for ENZ and 1.04 (0.9-1.20) for AA + P. No evidence of publication bias was observed. Conclusions: The aim of this study is to contrast the hypertension, psychiatric and central nervous system disorders safety profile of AA + P and ENZ. This analysis suggests that mCRPC patients treated with ENZ had a higher risk of developing hypertension, neurological and psychiatric disorders than the patients treated with AA + P. One may speculate that the affinity of ENZ for GABA receptor may play a role in the toxicities related to the central nervous system4.