CTLA4 and lung cancer: Even the immune checkpoint blockades, including programmed death-1/programmed death-ligand 1 (PD-1/PD-L1), and cytotoxic T lymphocyte associated antigen-4 (CTLA-4), which have been demonstrated robust results in melanoma, lung cancer, renal cell carcinoma, urothelial cancer, head and neck cancer and other malignancies (5), but most phase I and II clinical trials have failed to show any clinical efficacy in “cold tumor” pancreatic cancer (6).