Rituximab in the Treatment of Refractory Anti-HMGCR Immune-mediated Necrotizing Myopathy

Abstract

Objective A pathogenic role of anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibodies has been proposed. Our objective was to assess efficacy of rituximab (RTX) in anti-HMGCR immune-mediated necrotizing myopathy. Methods All patients who had been treated with RTX were retrospectively reviewed to assess features and outcome. Results Three of 9 patients demonstrated stable or improved muscle strength ± decline in creatine kinase levels, or T2/short-tau inversion recovery hypersignal decrease on magnetic resonance imaging following RTX treatment. RTX permitted intravenous immunoglobulin discontinuation and corticosteroid reduction to low dose in 2 patients. Conclusion One-third of patients with refractory anti-HMGCR had improved strength or other evidence of improved disease activity following RTX treatment.