The Current Role of Immunotherapy in mCRPC: A Systematic Review

Abstract

Background: The development of immunotherapy has shown promising results in several malignant diseases, including prostate cancer, calling for a systematic review of the current literature. This review aims to evaluate the present data and prospects of immune checkpoint inhibitors in metastatic Castration Resistant Prostate Cancer (mCRPC). Methods: Articles were identified via a systematic search of the electronic database Pubmed, in accordance with the PICO process and following the PRISMA guidelines. Articles in English studying immune checkpoint inhibitors in patients with mCRPC published between March 2010 and March 2020 were eligible for inclusion. Endpoints of interest were Overall Survival (OS), Progression-Free Survival (PFS), clinical Overall Response Rate (ORR), and Prostate-Specific Antigen (PSA) response rate. Results: Ten articles were identified as eligible for inclusion. The studies primarily explored the use of Ipilimumab, a CTLA-4 inhibitor, and Pembrolizumab, a PD-1 inhibitor. These drugs were both used either as monotherapy or in combination with other treatment modalities. The largest trial included in the review demonstrated no significant difference in overall survival between the intervention and placebo. However, two studies presented promising data combing immunotherapy and immune vaccines. Grade 3 and 4 adverse events ranging from 10.1% to 82.3%, whit diarrhea, rash, and fatigue were the most frequently reported. Forty relevant ongoing trials were identified exploring immunotherapy with or without a parallel treatment modality. Conclusion: Overall, the current data shows that the effect of immune checkpoint inhibitors as monotherapy may have limited impact on mCRPC, and the results from ongoing combinational trials are eagerly awaited.