CTLA4 and autoimmune disease: Considering that abatacept (exogenous CTLA4) is a drug for the treatment of autoimmune diseases, ipilimumab (anti-CTLA4) is an antitumor drug, and OX40 inhibitor is used for treating autoimmune diseases, it is speculated that the OX40 agonist receptor may also have antitumor activity.