Abatacept as a successful therapy for myositis—a case-based review

Only limited evidence exists on the therapeutic potential of biologic agents in the treatment of myositis. We present a brief review of the literature on off-label experiences of biologic agents in myositis, with a special interest in abatacept. Rituximab has been indicated to be beneficial and well tolerated in one large randomized controlled trial and many smaller studies. Initial data on tumour necrosis factor (TNF) inhibitors are conflicting. There are only a few case reports and mechanistic studies on the treatment of myositis with other biologics, including alemtuzumab, anakinra, tocilizumab and abatacept. We report a patient with severe myositis overlap syndrome, manifesting also as rheumatoid arthritis, peripheral vasculitis and interstitial lung disease. Her myositis was refractory to many conventional and biologic therapies but was well controlled with abatacept. This suggests that abatacept might be a beneficial option for the treatment of refractory myositis and that clinical trials are needed to further investigate its efficacy.