Biologic treatments for idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies are a group of acquired, heterogeneous, systemic diseases of skeletal muscle. As these conditions are uncommon, current treatment of myositis is based mainly on case reports and few randomised studies with small numbers of patients enrolled. Therefore, the current treatment paradigm is still relies primarily on clinical experience. High dose corticosteroids continue to be the first line therapy. In order to avoid side effects, the prednisolone dose should be reduced based on patient’s clinical response. Other immunosuppressive drugs are used in refractory cases, as well as steroid-sparing agents. Nevertheless, a Cochrane review concluded that there was insufficient evidence from the available studies to confirm the value of immunosuppressive agents in myositis. In patients with myositis resistant to conventional treatment, rituximab is a potential treatment option. Several agents could be of interest for future studies of myositis treatment; however more randomised controlled trials are needed to identify eligibility criteria, outcome predictors and the adequate regimen. The identification of responsive patients and specific therapies targeting the correct myositis subset may be cost-effective and potentially prevent incorrect use of biologics.