PDCD1LG2 and squamous cell lung carcinoma: NSCLC accounts for about 80–85% of lung cancer, and lung squamous cell carcinoma (LSCC) accounts for about 25–30% of NSCLC[2] After a combination of surgery, radiation and chemotherapy, the 5-year survival rate of patients with advanced LSCC is only 5%.[3] Programmed death 1 (PD-1) is an inhibitory receptor expressed on T cells, and its ligands include programmed death ligand 1 (PD-L1) and programmed death ligand 2 (PD-L2).