CD274 and pituitary tumor: Considering that the combination of CTLA-4 antibody with the “ectopic” expression of CTLA-4 antigen on normal pituitary endocrine cells can cause damage to normal pituitary tissue, the use of the CTLA-4 antibody as an adjuvant to other checkpoint inhibitors, such as anti-PD-1 and anti-PD-L1, for the treatment of pituitary tumors, may be a promising approach.