CTLA4 and cancer: In addition, “Cytotoxic T-Lymphocyte–Associated Protein 4 (CTLA-4)” is another critical immune checkpoint molecule that regulates early T cell activation, and its inhibitory role was first elucidated by Dr. James P. Allison and others [7], ultimately contributing to the development of immune checkpoint inhibitors targeting the CTLA-4 pathway in cancer immunotherapy.