Rheumatic immune-related adverse events associated with cancer immunotherapy: A nationwide multi-center cohort

Although immune checkpoint inhibitors (ICI) have revolutionized cancer therapy, their use is associated with immune toxicities referred to as immune-related adverse events (irAE). Here we describe the clinical presentation and management of rheumatic immune-related adverse events (Rh-irAE) in a national multi-center cohort.

All patients presenting with Rh-irAE at 9 academic sites across Canada between January 2013 and January 2019 were identified and included in this retrospective cohort study. Standardized data were extracted by chart review.

117 patients who developed 136 Rh-irAE were identified. The most frequent Rh-irAE was symmetric polyarthritis (n = 45). Other Rh-irAE included non-inflammatory musculoskeletal symptoms (n = 18), polymyalgia rheumatica (n = 17) and myositis (n = 9). Prednisone was the most commonly used treatment (n = 76) with a mean maximum dose of 60 ± 74 mg/d and duration of treatment of 8.4 ± 11 months. Forty-two patients required conventional synthetic disease-modifying anti-rheumatic drugs (DMARD) and two required biologic DMARD to control the Rh-irAE. ICI was discontinued due to the Rh-irAE in 22 patients. There were no deaths related to Rh-irAE. Treatment of the Rh-irAE did not appear to negatively impact the tumor response to immunotherapy with 23 patients experiencing tumor progression prior to treatment of the Rh-irAE and 13 following treatment.

In this largest multi-center cohort of Rh-irAE described to date, symmetric polyarthritis was the most common Rh-irAE. There was considerable heterogeneity of treatment, although this did not appear to negatively impact the anti-tumor response. This study can inform the development of evidence-based recommendations to optimize Rh-irAE and cancer outcomes in patients treated with ICI.