This review will encompass the fundamental principles and existing research on ICB therapy in prostate cancer, with a particular emphasis on a range of potential predictive biomarkers, including PD-L1 expression levels, microsatellite instability (MSI), DNA mismatch repair (dMMR), cyclin-dependent kinase 12 (CDK12) deficiency and tumour mutational burden (TMB), among others. Here, CDK12 is linked to Familial prostate cancer.