This review synthesizes the biological drivers of PD-L1 regulation in PCa, dissects key methodological sources of heterogeneity in PD-L1 assessment, summarizes clinicopathological and therapeutic correlations, and outlines emerging biomarkers and approaches (including mismatch repair deficiency/microsatellite instability, tumor mutational burden, gene-expression signatures, liquid biopsies, and neuro-immune interactions) that may enable more actionable patient stratification. The gene discussed is CD274; the disease is posterior cortical atrophy.