PDCD1 and non-small cell lung carcinoma: Based on the above results, we hypothesize that increased proportion of tumor-infiltrating BTLA+CD8+ T cells might lead to failure of anti-PD-1/PD-L1 therapy in NSCLC and that combined anti-BTLA therapy might enhance the efficacy of anti-PD-1/PD-L1 therapy in NSCLC.