PDCD1 and lung cancer: In a meta-analysis involving 4,174 patients with advanced tumors (including lung cancer, kidney cancer, head and neck cancer, melanoma, and urothelial cancer), the patients received nivolumab, pembrolizumab, or atezolizumab treatment, respectively, and the analysis results showed that both PD-L1-positive and PD-L1-negative patients can benefit from PD-1 or PD-L1 blocking therapy, in which the survival benefit of pembrolizumab treatment for PD-L1-negative patients was minimal.