[Myositis induced by immune checkpoint inhibitor therapy].

backgroundImmune-mediated myositis can be a severe side effect of cancer treatment involving immune checkpoint inhibitors (ICI). As a distinct type of rheumatic immune-related adverse events (irAE), it presents challenges in terms of diagnosis and patient management. The high mortality and the potential for rapid progression necessitates prompt treatment.

objectiveThis article provides a practice-oriented overview of myositis-induced irAEs, focusing on the diagnostic and treatment management and the prognostic implications. MATERIAL AND

methodsA selective literature review was conducted, covering current studies, registry data and pharmacovigilance data as well as guidelines for recognizing and treating ICI-associated myositis irAEs.

resultsMyositis-induced irAEs typically manifest within 1 month of initiating ICI therapy. The incidence is between 0.5% and 1%; however, it is significantly higher with ICI combination therapies. In around half of the cases, myositis is the only irAE manifestation. The number of cases of neuromuscular irAE overlap with myocarditis and/or myasthenia rose from 3.7% before to 8.3% after 2017. Around 20% of cases of isolated myositis require ventilation, compared to 50-80% of cases of overlap syndrome, which is associated with a high mortality of 40%.

conclusionIf a myositis-irAE is suspected, high-dose glucocorticoid therapy should be initiated immediately. The treatment often includes glucocorticoid-sparing medications. For severe cases, abatacept should be considered as a salvage therapy. Early detection and close collaboration between all medical specialty disciplines involved are crucial for the prognosis of patients.