The Food and Drug Administration (FDA) has granted Orphan Drug designation to zilucoplan (Ra Pharmaceuticals) for the treatment of generalized myasthenia gravis (gMG) and other rare, tissue-based complement-mediated diseases.

Zilucoplan is a synthetic, macrocyclic peptide inhibitor of complement component 5 (C5) that binds to and inhibits the cleavage of C5 into C5a and C5b preventing 3 pathways of complement activation. Zilucoplan uses the Company’s proprietary Extreme Diversity platform to deliver macrocyclic peptides designed for subcutaneous, self-administration. 

The designation is supported by data from a 12-week, randomized, double-blind, placebo-controlled, phase 2 clinical trial that evaluated the efficacy and safety of zilucoplan in adult patients with gMG. The primary end point of the study was change from baseline in Quantitative Myasthenia Gravis (QMG) score; change from baseline in Myasthenia Gravis-Activities of Daily Living (MG-ADL) scale was a secondary outcome measure. 

Results demonstrated zilucoplan dosed at 0.3mg/kg SC achieved a statistically significant mean reduction from baseline of 6.0 points in the QMG score (placebo-adjusted change = -2.8; P =.05) and a mean reduction from baseline of 3.4 points in the MG-ADL score (placebo-adjusted change = -2.3; P =.04), with no patients treated with zilucoplan requiring rescue therapy. Additionally, the Company conducted an open-label, long-term, phase 2 extension study, in which patients treated with placebo that crossed over to zilucoplan 0.3mg/kg after 12 weeks experienced statistically significant improvements for all efficacy end points.

Regarding safety, zilucoplan demonstrated a favorable safety and tolerability profile with no serious adverse events observed. The Company plans to initiate a pivotal phase 3 trial of zilucoplan in the second half of 2019.

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“We’ve designed zilucoplan, a macrocyclic peptide inhibitor of C5, as an easy-to-use, self-administered subcutaneous treatment option to address the underlying cause of gMG through targeted complement control,” said Doug Treco, PhD, President and Chief Executive Officer of Ra Pharma. “With site activations underway, we are on track to initiate our single, pivotal, 12-week, Phase 3 trial of zilucoplan for the treatment of gMG in the second half of this year.”

For more information visit rapharma.com.

This article originally appeared on MPR