Arthritis After Cancer Immunotherapy: Symptom Duration and Treatment Response.

Objective Musculoskeletal manifestations of immune-related adverse events (irAEs) after checkpoint inhibitor immunotherapy for cancer remain incompletely characterized and poorly understood. A recently published case series suggested that immunotherapy-induced arthritis is an aggressive process requiring high-dose corticosteroids. Methods This was a retrospective chart review of all patients with musculoskeletal irAEs first seen by one of the authors between 2014 and 2016. All patients had been treated for a malignancy with immune checkpoint inhibitors targeting PD-1 (nivolumab, pembrolizumab), PD-L1 (durvalumab), and/or CTLA-4 (ipilimumab, tremelimumab) at Memorial Sloan Kettering Cancer Center. Results We identified 10 patients with a mean +/- SD age of 63.2 +/- 9.7 years. Seven were treated with a combination of checkpoint inhibitors and 3 with nivolumab monotherapy. Four patients developed inflammatory polyarthritis, 4 oligoarthritis, and 2 tenosynovitis. Six were antinuclear antibody positive and 2 had anti-cyclic citrullinated peptide antibodies. Mean +/- SD time from the first dose of immunotherapy until joint involvement was 6.3 +/- 4.3 months. All 10 patients were treated with systemic corticosteroids, but 6 of 10 required <= 20 mg per day of prednisone. Five patients received steroid-sparing agents. Mean +/- SD time until resolution of joint symptoms after the last dose of immunotherapy was 9.2 +/- 6.1 months. Conclusion Musculoskeletal irAEs can manifest as a rheumatoid arthritis-like polyarthritis, oligoarthritis, tenosynovitis, or polymyalgia rheumatica. Musculoskeletal symptoms can last more than a year, but they can generally be managed with low to moderate doses of corticosteroids.