Could CGRP mAbs for migraine trigger rheumatoid arthritis? Insights from a case report

Background: Case reports suggest that calcitonin gene-related peptide monoclonal antibodies (CGRP mAbs) may trigger inflammatory flares in patients with autoimmune diseases. Case Description: A 56-year-old woman with a history of severe migraines, experienced improvement in migraine frequency and intensity after starting fremanezumab 225 mg monthly. However, three months into treatment, she developed symmetric inflammatory polyarthralgias. Physical examination confirmed polyarthritis in the hands, feet, and knees. Laboratory tests showed elevated inflammatory markers and positive anti-cyclic citrullinated peptide antibodies, with baseline X-rays of hands, feet, and knees being normal. Diagnosed with rheumatoid arthritis (RA), she was treated with prednisolone, methotrexate (MTX), folic acid, calcium carbonate, and cholecalciferol, resulting in clinical improvement. Despite recommendations, she continued fremanezumab; her articular symptoms persisted after discontinuation. Later, she switched to leflunomide 20 mg due to gastrointestinal intolerance to MTX and is currently in remission. Discussion/Conclusions: CGRP mAbs are effective for migraine prevention, but cases of immune-mediated disease flares are documented. This case suggests a possible association between CGRP mAbs and RA onset. Further research is essential to understand the impact of CGRP modulation in autoimmune diseases.