Biological Therapies in Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIM) are a rare group of disorders that feature progressive immune-mediated skeletal muscle destruction along with skin, lung, and joint involvement. Management of IIMs necessitates glucocorticoid therapy followed by conventional steroid-sparing agents to control disease activity. In the settings of refractory myositis or life-threatening manifestations, e.g. lung involvement or oropharyngeal dysphagia, second-line therapies are needed to minimize disease burden, avoid end-organ damage and steroid toxicity, and decrease mortality. These therapies may include biological disease-modifying antirheumatic drugs (bDMARDs), and to a lesser extent, targeted synthetic disease-modifying antirheumatic drugs (TSD). This article reviews the current use of bDMARDs, e.g. intravenous immunoglobulin and rituximab, and a TSD—Janus kinase inhibitors (JAKI)—along with their indications, efficacy, and safety in managing IIM.