Ra Pharmaceuticals, Inc. announced the initiation of dosing in its Phase 2 clinical trial of zilucoplan for the treatment of immune-mediated necrotizing myopathy (IMNM). The randomized, double-blind, placebo-controlled, multi-center, Phase 2 clinical trial will evaluate the safety, tolerability, and efficacy of zilucoplan in patients with IMNM who are positive for anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) or anti-signal recognition particle (SRP) autoantibodies. Patients will be randomized in a 1:1 ratio to receive daily subcutaneous (SC) doses of 0.3 mg/kg zilucoplan or placebo. Randomization will be stratified based on antibody status (anti-HMGCR+ versus anti-SRP+). The trial is expected to enroll approximately 24 patients with an eight-week treatment period. The primary endpoint will be change in creatine kinase (CK) from baseline to week eight. Following completion of the trial, patients will have the option to enter into an open-label long-term extension study with zilucoplan.