Checkpoint inhibitors and arthritis

It was with interest that we read the article by Belkhir et al 1 in the recent Annals of Rheumatic Disease . The article described the first report of rheumatoid arthritis (RA) and polymyalgia rheumatica developing after the use of immune checkpoint inhibitors to treat a variety of cancers. We found the article interesting and informative but noted that in all of their 10 reported cases, the patients seroconverted from rheumatoid factor (RF) or cyclic citrullinated peptide antibody (CCP) negative to positive, supporting their claim that ‘rheumatoid arthritis’ may develop after immune checkpoint inhibitor treatment. The report by Belkhir et al is in contrast to our experience managing …