Musculoskeletal rheumatic complications of immune checkpoint inhibitor therapy: A single center experience

The use of immune checkpoint inhibition (ICI) has revolutionized cancer treatment. However, these medications are associated with significant and potentially debilitating immune-related adverse events (irAEs). While certain toxicities have been well studied, rheumatic complications have been less widely recognized and characterized.

We report our experience of patients who were evaluated by rheumatology after the development of a suspected rheumatic irAE following ICI treatment. Cases of rheumatic irAEs were included if active rheumatic signs or symptoms developed during or after ICI treatment and were confirmed by a treating rheumatologist.

Twenty-nine patients were evaluated by rheumatology for suspected rheumatic irAEs. Eighteen patients had confirmed toxicity including inflammatory arthritis (n = 12) and PMR (n = 6). Twelve patients had de novo toxicity and six had a flare of a pre-existing rheumatic condition. The onset of de novo toxicity occurred late into treatment (median 38 weeks), while patients with pre-existing rheumatic disease flared soon after initiation of ICI treatment (median 4.6 weeks). Management often required systemic or intra-articular steroids, with initiation of disease modifying anti-rheumatic drug (DMARD) therapy in those unable to wean off steroids.

De novo rheumatic irAEs are generally delayed in onset after ICI initiation, while flares of pre-existing rheumatic conditions occur shortly after ICI initiation. Effective management often requires systemic corticosteroids as well as DMARDs in a subset of patients. Future prospective studies are needed to accurately describe the incidence and spectrum of rheumatic irAEs and to identify the most effective management strategies.