Prognostic Value of Immune Checkpoints in Prostate Cancer: A Systematic Review and Meta-Analysis of Reconstructed Time to Event Data

Introduction: Various molecular pathways are proposed to predict the prognosis of prostate cancer. However, due to previous achievements in prostate cancer management by immune checkpoint (IC) inhibitors, multiple studies have addressed the ICs role in the prognosis of prostate cancer and PD-L1 is known as one of the most cited ICs in this era. Objective: To systematically review the prognostic value of the immune checkpoints (ICs) in prostate cancer. Methods: This was a systematic review and meta-analysis study on online databases for studies reporting hazard ratios (HRs) of different survival outcomes of prostate cancer based on the dichotomized gene expression data of immune checkpoints. Studies presenting Kaplan Meier (KM) curves were included and time to event data was extracted for the KM reconstruction and HRs calculations for meta-analysis. Newcastle-Ottawa scale for cohort studies was used to assess the quality of studies. Results: In the qualitative review, among the relevant selected ICs, 7 studies were available for PD-L1. Six studies were included in the meta-analysis for PD-L1. Concerning the high PD-L1 status as the reference, the chance of Biochemical Recurrence Free Survival was statistically lower in cases with low PD-L1 status (HR= 0.69, 95%CI of 0.57 to 0.58), under a fixed effect model with no heterogeneity (I2= 8%). There was a low possibility of publication bias based on the funnel plot. Conclusion: High PD-L1 expression role in the prognosis of prostate cancer was shown to be supported by good levels of high-quality cohort studies, supported by pooled quantitative results of a meta-analysis.