Ra Pharmaceuticals, Inc. announced the successful completion of End-of-Phase 2 interactions with the U.S. Food and Drug Administration (FDA) for its Phase 3 clinical trial of zilucoplan for the treatment of generalized myasthenia gravis (gMG). Based on feedback provided by the FDA, Ra Pharma plans to initiate a single, pivotal, Phase 3, randomized, double-blind, placebo-controlled trial evaluating the efficacy of a once-daily, subcutaneously (SC) self-administered dose of 0.3 mg/kg of zilucoplan versus placebo. The trial is expected to enroll approximately 130 patients with gMG who are acetylcholine receptor (AChR)-antibody-positive, regardless of their prior therapies. The primary endpoint will be the change in the MG Activities of Daily Living (MG-ADL) score from baseline to week 12. Following completion of the Phase 3 clinical trial, patients will have the option to enroll into an open-label, long-term extension study. Ra Pharma anticipates initiating the Phase 3 clinical trial in the second half of 2019. With alignment reached on a single, 12-week, pivotal Phase 3 trial, Ra Pharma has decided to prioritize gMG as the lead indication for zilucoplan as part of its goal to build a leading complement-focused neurology franchise. Leveraging the unique properties of a small peptide C5 inhibitor, the Company plans to expand development into other tissue-based, complement-mediated disorders with high unmet medical need. This effort includes the initiation of a Phase 2 study in an undisclosed neuromuscular indication in the second half of 2019. As a result, the Company has decided to postpone further clinical development of zilucoplan in paroxysmal nocturnal hemoglobinuria (PNH). Dosing will continue in the Company's long-term extension of the Phase 2 PNH program. In addition, the Company continues to advance development of zilucoplan extended release (XR) and its first-in-class oral small molecule C5 inhibitor. The End-of-Phase 2 interactions with the FDA follow the successful completion of a Phase 2, multi-center, randomized, double-blind, placebo-controlled clinical trial evaluating zilucoplan for the treatment of gMG. Rapid, clinically meaningful, and statistically significant improvements in the pre-specified primary and key secondary endpoints were observed for both zilucoplan dose groups tested versus placebo at 12 weeks. Zilucoplan dosed at 0.3 mg/kg SC daily achieved a mean reduction from baseline of 6.0 points in the Quantitative Myasthenia Gravis (QMG) score (placebo-corrected change = -2.8; p=0.05) and a mean reduction from baseline of 3.4 points in the MG-ADL score (placebo-corrected change = -2.3; p=0.04). No patients treated with the 0.3 mg/kg dose of zilucoplan required rescue therapy compared with 20% in the placebo arm. Treatment with zilucoplan had a favorable safety and tolerability profile in the study, consistent with previously-completed Phase 1 and Phase 2 studies. The majority of adverse events (AEs) reported were mild and were not considered by the investigators to be related to study drug. There were no serious AEs observed related to treatment with zilucoplan.