LAG3 and small cell lung carcinoma: Immune checkpoint blockade (ICB) therapies against programmed death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), lymphocyte-activation gene 3 (LAG-3) and CTL antigen 4 (CTLA-4) are FDA-approved for over 50 types of cancer, including melanoma, non-small cell lung cancer, small cell lung cancer, renal cell cancer, head and neck squamous cell carcinoma, colorectal cancer and hepatocellular carcinoma (7, 8).