CTLA4 and cancer: However, while PD-1/PD-L1 and CTLA-4 immune checkpoint molecule blockade holds great promise as an effective immunotherapeutic approach to treat cancer in experimental and clinical conditions displaying different degrees of success in some cancers including melanoma, non-small cell lung carcinoma (NSCLC), and urothelial carcinoma, many reports have shown low or no responsiveness in other cancer types such as gastrointestinal, breast, pancreatic, prostate, sarcoma, and colorectal cancers [9].