Current Status of Monoclonal Antibodies-Based Therapies in Castration-Resistant Prostate Cancer: A Systematic Review and Meta-Analysis of Clinical Trials

Background Multiple patients with prostate cancer become resistant to castration therapies, which is termed castration-resistant prostate cancer (CRPC). Purpose The purpose of this review is to assess the status of efficacy (≥50% decline in prostate-specific antigen (PSA), progression-free survival (PFS), and overall survival (OS)) and safety (grade 3-4 adverse effects) of monoclonal antibodies in CRPC. Data source We searched databases including PubMed, Embase, Cochrane, Web of Science, and ClinicalTrials.gov. Results Hazard ratios of PFS and OS were 0.77 (95% CI = 0.69-0.87, I = 53%) and 0.98 (95% CI = 0.86-1.11, I = 40%), respectively, in the favor of monoclonal antibodies as compared to placebo. Risk ratio (RR) of >50% decline in PSA was 1.99 (95% CI = 0.97-4.08, I = 53%) in favor of monoclonal antibodies. Pooled incidence of >50% decline in PSA levels was 15% (95% CI = 0.1-0.23, I = 83%), 29% (95% CI = 0.14-0.51, I = 93%), 63% (95% CI = 0.49-0.76, I = 77%), and 88% (95% CI = 0.81-0.93, I = 0%) in single, two, three, and four-drug regimens, respectively. Conclusion Monoclonal antibodies are well tolerated and showed better PFS as compared to placebo. However, OS was only improved with ipilimumab. Denosumab delayed skeletal-related adverse events as compared to zoledronic acid. More multicenter double-blind clinical trials may be needed to confirm these results.