Over the past century, there has been a significant increase in the amount of research on the connection between inflammatory myopathy and cancer. Immune checkpoint inhibitor-associated myositis (ICI myositis) is now a new participant in the expanding area of inflammatory myopathy. Clinical diagnosis of inflammatory myopathy following the start of immunosuppressive therapy for cancer care is indicative of immune checkpoint inhibitor-associated myositis. 

Current research showed that ICI myositis has a low prevalence but a significant fatality rate, particularly when it involves myasthenia gravis and myocarditis. Muscle soreness and weakness were common symptoms of immune checkpoint inhibitor-associated myositis. It seldom presented as interstitial lung disease or dermatitis and was generally seronegative with scattered endomysial inflammatory infiltrates on biopsy. Other neurological immune-related adverse effects, including myasthenia gravis were included in the differential diagnosis of ICI myositis. 

Due to the absence of strong studies to favor one immunomodulating drug over another, the therapeutic strategy comprised high doses of corticosteroids together with a choice of steroid-sparing medication(s). The inclusion criteria for ICI myositis employed in earlier research were broad. In order to establish a uniform definition and enable comparison between research, researchers analyzed previously employed inclusion criteria and propose an expertise-based categorization criterion. To enhance patient assessment and care, prospective translational and clinical research that clarified the pathogenesis of ICI myositis was urgently needed.

Reference: journals.lww.com/jclinrheum/Abstract/2022/10000/Immune_Checkpoint_Inhibitor_Associated_Myositis__A.7.aspx