PHOENIX – , a new analyses show.
“The information [in the studies] is valuable in making clinical decisions in managing myasthenia gravis, which is a chronic autoimmune condition that requires long-term use of immunosuppressives,” said Xinli Du, MD, PhD, an assistant professor in the department of neurology at Virginia Commonwealth University in Richmond, who was not involved in the research.
“Compared with conventional immunosuppressants, which take 3-9 months to know if the patient will respond, this is definitely a game-changer,” she said.
The research was presented at the 2023 annual meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM).
FDA approval
Approved by the U.S. Food and Drug Administration in October, the targeted peptide inhibitor of complement component 5 represents the only once-daily self-administered subcutaneous injection for adult patients with acetylcholine receptor autoantibody–positive (AChR+) generalized myasthenia gravis.
The multicenter, phase 3, placebo-controlled RAISE trial demonstrated that zilucoplan was associated with significant improvement in myasthenia gravis–specific outcomes in adult patients with mild to severe AChR+ generalized myasthenia gravis.
Of note, approximately 40% of patients in the zilucoplan phase 2 and 3 clinical trials have a significant response as early as the first week of treatment. For the current post hoc analysis, first author Miriam Freimer, MD, and colleagues took a closer look at the longer-term outcomes in these patients in the ongoing RAISE-XT open-label extension study.
In these two double-blind studies, patients were randomly assigned to receive either daily subcutaneous injections of 0.3 mg/kg zilucoplan or placebo.
Among 93 patients receiving zilucoplan in the two studies, 40 (43%) were identified as early responders based on having at least a 3-point reduction from baseline on the Myasthenia Gravis Activities of Daily Living scale (MG-ADL) within 1 week of treatment, and 31 (33%) qualified based on having at least 5-point reductions in Quantitative Myasthenia Gravis (QMG), at week 1.
Of these early responders, more than 80% meeting the MG-ADL and 85% meeting QMG criteria continued to show a treatment response at each assessment through week 60 in the open-label RAISE-XT trial.
Furthermore, week 1 responders maintained their response for 88.1% of their total treatment time in the MG-ADL group and 88.8% of their total treatment time on treatment in the QMG group, representing a median zilucoplan treatment duration of 450 days.
Of note, the week 1 early responders had no significant differences, compared with the study’s overall population. Participants had a mean age of 49.6 years versus 52.9 years in the overall population. Approximately 40% of patients in both studies were men, and 60%-64% were disease class III as assessed by the Myasthenia Gravis Foundation of America criteria.
“It is very exciting to see such a high response of rapid responders. This means that some patients may be able to avoid steroids or be able to taper them faster than with other accepted treatments for myasthenia gravis,” said Dr. Freimer, director of the division of neuromuscular disorders and the codirector of the Myasthenia Gravis Clinic at the Ohio State University in Columbus.