Abstract:

Aims: Immune-related adverse events (irAEs) may be observed due to the mechanism of action of immune checkpoint inhibitors (ICIs). This study investigated the frequency of rheumatologic irAEs and characteristics of the patients who developed rheumatologic irAEs due to ICIs. Methods: This single-center, prospective, and observational study was conducted with the patients who received ICIs due to malignancy between December 2018 and November 2019. The demographic characteristics, clinical characteristics, and inflammatory and non-inflammatory irAEs were evaluated. Results: The study included 38 patients (mean age: 54.5±19.2 years, male: 65.8%). Thirty-one (86.1%) patients received nivolumab, 4 (11.1%) patients received atezolizumab, and one (2.8%) patient received pembrolizumab. The median number of treatment cycles with ICIs was 11.5. Rheumatologic irAEs were observed in 20 (55.6%) patients. Four (11.2%) patients had inflammatory and 16 (44.5%) patients had non-inflammatory rheumatologic irAEs. The median time from the initiation of ICI treatment to the development of rheumatologic irAEs was 3 months. All patients with inflammatory rheumatologic irAEs were on treatment with a programmed cell death protein 1 inhibitor. Prednisolone and methotrexate were the drugs used to improve inflammatory musculoskeletal symptoms. Conclusions: Inflammatory rheumatological irAEs due to ICIs were mostly polymyalgia rheumatica and rheumatoid arthritis-like symptoms. Low-dose corticosteroid therapy may be the appropriate choice of treatment of inflammatory rheumatologic irAEs.

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