Utility of Myositis-Specific Autoantibodies for Treatment Selection in Myositis

Purpose of Review Autoimmune myopathies (IMs) are a group of diseases characterized by muscle weakness and inflammatory infiltrates on the muscle biopsy. `However, muscle involvement is not always present and other organs and tissues (lung, skin, and joints) are commonly affected. The most accepted classification for IM includes dermatomyositis, sporadic inclusion body myositis, immune-mediated necrotizing myopathy, polymyositis, and overlap myositis. Seventy percent of the autoantibodies that IM patients have are myositis-specific autoantibodies (MSAs). Importantly, MSAs are associated with specific clinical phenotypes in IM patients. The therapy of IMs consists of glucocorticoids, immunosuppressants, biologic, and immunomodulatory drugs, but there is recent evidence that patients with some types of MSAs respond better to certain treatments. The purpose of this review is to summarize the IM treatment from an autoantibody perspective. Recent Findings Each MSA is maybe associated with the activation of specific pathogenic pathways which can be effectively targeted by specific drugs. The last few years have shown multiple examples of successful treatments for each MSA group of patients as we will describe in the following paragraphs. The adverse effects of the IM therapeutic agents and some patients' refractoriness call for a continued search for better and more targeted therapies. MSA groups should be considered for a treatment decision.