PDCD1 and prostate cancer: In another study that investigated correlations between PD-1, PD-L1, and clinical outcomes in patients with prostate cancer, it was found that both PD-1 and PD-L1 were significantly upregulated in malignant tissue when compared to benign tissue (PD-1–1.5% vs. 7.7%, p = 0.003; PD-L1–0.5% vs. 13.2%, p < 0.001).