Immune Checkpoint Inhibitor Associated Rheumatoid Arthritis

Immune checkpoint inhibitors (ICI) have revolutionized cancer therapy over the past decade. Unfortunately, immune related adverse events (irAEs) are common, including rheumatologic adverse events. These rheumatologic irAEs include de novo rheumatoid arthritis-like presentations or flares of pre-existing rheumatoid arthritis, collectively called ICI-associated rheumatoid arthritis. In this article we review the different mechanisms of disease activity and management approaches including use of conventional (cs) DMARDs and biologic (b) DMARDs in this patient population. Other forms of ICI-induced inflammatory arthritis e.g., PMR-like or Spondylarthritis-type IA, are beyond the scope of this review.

The heterogeneous presentations of inflammatory arthritis in patients receiving immune checkpoint inhibitors has made this a challenging area to study. Nonetheless, recent studies are providing better understanding on the mechanisms of de novo disease and flares in patients with rheumatoid arthritis. About half of patients with pre-existing rheumatoid arthritis flare after receiving checkpoint inhibitors. Persistent arthritis is often encountered in patients receiving combination immune checkpoint inhibitors. Outcomes on overall survival do not differ in rheumatoid arthritis patients receiving checkpoint inhibitors compared to their non-arthritis counterparts. Rheumatologist play a critical role in the management of active rheumatoid arthritis induced by checkpoint inhibitors. Collaboration with oncology colleagues will continue to be a crucial component in providing quality care to these patients. While the use of glucocorticoids is often the first line therapy for active inflammatory arthritic disease, we recommend earlier consideration of DMARDs just as we inverted the treatment pyramid several decades ago, for rheumatoid arthritis.