PDCD1 and non-small cell lung carcinoma: Checkpoint inhibitors targeting CTLA-4, PD-1, and PD-L1 now form part of first or second-line standard-of-care in melanoma, non-small cell lung cancer (NSCLC), advanced head and neck squamous cell cancer (HNSCC), renal cancer and urothelial cancer, among others (targets summarised in Table 1).