Immune checkpoint inhibitor related myositis: an observational, retrospective, pharmacovigilance study

Immune checkpoint inhibitors (ICIs) show promise in cancer treatment, but recent cases highlight myositis as a serious complication. We did a retrospective study on drug safety using FAERS data up to Q3 2022, focusing on immune checkpoint inhibitors (ICIs) and myositis. We used IC and ROR to assess the association. Logistic regression in R 3.2.5 helped identify factors linked to fatal outcomes. We identified 558 cases of ICIs-associated myositis. Our study found a significant link between ICIs and myositis (ROR 15.54 [14.23–16.96], IC 3.79 [3.66–3.92], see Figure 1). Notably, myositis was more common in patients on ICI combination therapy compared to monotherapy (ROR 1.72 [1.39–2.11], IC 0.63 [0.30–0.93]). Age increased the risk of ICI-associated myositis and was also a factor in fatality (p = 0.011). Common accompanying adverse events included myocarditis (21.33%), severe myasthenia gravis (16.49%), and malignant neoplasm progression (8.06%). Fatal cases were more common when myositis was accompanied by myocarditis, severe myasthenia gravis, or malignant neoplasm progression. Clinicians must note the risk of ICI-associated myositis, especially dangerous in older patients or when combined with other issues like myocarditis or severe myasthenia gravis.