PDCD1 and bladder transitional cell carcinoma: This led to the approval of therapeutic inhibitors of programmed cell death 1 (PD-1) pathway, pembrolizumab, nivolumab, and cemiplimab, and of the programmed cell death ligand 1 (PD-L1) pathway, atezolizumab, durvalumab, and avelumab, by the US Food and Drug Administration (FDA) for the treatment of advanced melanoma, non-small-cell lung cancer, renal cell carcinoma, head and neck squamous cell carcinoma (HNSCC), Hodgkin's lymphoma, squamous cell cancer of the skin, and urothelial bladder cancer.