Clinical Effects of the Self-administered Subcutaneous Complement Inhibitor Zilucoplan in Patients With Moderate to Severe Generalized Myasthenia Gravis

Abstract

; and the Zilucoplan MG Study Group IMPORTANCE Many patients with generalized myasthenia gravis (gMG) have substantial clinical disability, persistent disease burden, and adverse effects attributable to chronic immunosuppression. Therefore, there is a significant need for targeted, well-tolerated therapies with the potential to improve disease control and enhance quality of life. OBJECTIVE To evaluate the clinical effects of zilucoplan, a subcutaneously (SC) self-administered macrocyclic peptide inhibitor of complement component 5, in a broad population of patients with moderate to severe gMG. DESIGN, SETTING, AND PARTICIPANTS This randomized, double-blind, placebo-controlled phase 2 clinical trial at 25 study sites across North America recruited participants between December 2017 and August 2018. Fifty-seven patients were screened, of whom 12 did not meet inclusion criteria and 1 was lost to follow-up after randomization but before receiving study drug, resulting in a total of 44 acetylcholine receptor autoantibody (AChR-Ab)-positive patients with gMG with baseline Quantitative Myasthenia Gravis (QMG) scores of at least 12, regardless of treatment history. INTERVENTIONS Patients were randomized 1:1:1 to a daily SC self-injection of placebo, 0.1-mg/kg zilucoplan, or 0.3-mg/kg zilucoplan for 12 weeks. MAIN OUTCOMES AND MEASURES The primary and key secondary end points were the change from baseline to week 12 in QMG and MG Activities of Daily Living scores, respectively. Significance testing was prespecified at a 1-sided α of .10. Safety and tolerability were also assessed. RESULTS The study of 44 patients was well balanced across the 3 treatment arms with respect to key demographic and disease-specific variables. The mean age of patients across all 3 treatment groups ranged from 45.5 to 54.6 years and most patients were white (average proportions across 3 treatment groups: 78.6%-86.7%). Clinically meaningful and statistically significant improvements in primary and key secondary efficacy end points were observed. Zilucoplan at a dose of 0.3 mg/kg SC daily resulted in a mean reduction from baseline of 6.0 points in the QMG score (placebo-corrected change,-2.8; P = .05) and 3.4 points in the MG Activities of Daily Living score (placebo-corrected change,-2.3; P = .04). Clinically meaningful and statistically significant improvements were also observed in other secondary end points, the MG Composite and MG Quality-of-Life scores. Outcomes for the 0.1-mg/kg SC daily dose were also statistically significant but slower in onset and less pronounced than with the 0.3-mg/kg dose. Rescue therapy (intravenous immunoglobulin or plasma exchange) was required in 3 of 15, 1 of 15, and 0 of 14 participants in the placebo, 0.1-mg/kg zilucoplan, and 0.3-mg/kg zilucoplan arms, respectively. Zilucoplan was observed to have a favorable safety and tolerability profile. CONCLUSIONS AND RELEVANCE Zilucoplan yielded rapid, meaningful, and sustained improvements over 12 weeks in a broad population of patients with moderate to severe AChR-Ab...

Update on immune‐mediated therapies for myasthenia gravis

“…Twenty percent of patients in the placebo group and 7% in the low‐dose (0.1 mg/kg) zilucoplan group needed rescue therapy with IVIg or PLEX compared with none in the high‐dose (0.3 mg/kg) group. Zilucoplan was well‐tolerated and safe 11 . The phase 3 study (Table 3) is ongoing.…”

Complement Inhibitor Therapy for Myasthenia Gravis

“…The second phase 2 trial (ClinicalTrials.gov Identifier: NCT03315130), sponsored by Ra Pharmaceuticals was a prospective, double-blind, placebo-controlled study of 44 AChR+ gMG patients over 12 weeks followed by an open-label extension (OLE) trial that continues at this time (50). This study used zilucoplan, a small (3.5-kDa), 15-amino acid macrocyclic peptide, that binds to C5 with high affinity and specificity and also binds to the domain of C5 that corresponds to C5b and thereby also blocks binding of C5b to complement component C6 (51).…”

Monoclonal Antibody-Based Therapies for Myasthenia Gravis

“…Another complement inhibitor with a dosing advantage is zilucoplan, a small molecule, which is self-administered daily by subcutaneous injection. It has been found to be safe and effective in a phase II trial [55] and phase III evaluation began in 2019 and is likely to be completed in 2021 (NCT04115293).…”