PD‐1 expression is increased in synovial tissues in patients with rheumatoid arthritis (RA), but the PD‐1 pathway is downregulated during RA disease progression, suggesting that this pathway might be involved in the development of RA.5 The CTLA‐4 pathway also plays an important role in the pathogenesis of RA, and abatacept, a fusion protein composed of CTLA‐4 and the Fc region of human immunoglobulin‐1, has already been approved by the FDA for the treatment of RA.6 Furthermore, the PD‐1 pathway has also been shown to be involved in preventing lupus‐like symptoms in mouse models.7 This evidence concerns the gene CTLA4 and rheumatoid arthritis.