Effect of efgartigimod on muscle group subdomains in participants with generalized myasthenia gravis: post hoc analyses of the phase 3 pivotal ADAPT study

Abstract

Background and purposeGeneralized myasthenia gravis (gMG) is a rare, chronic, neuromuscular autoimmune disease mediated by pathogenic immunoglobulin G (IgG) autoantibodies. Patients with gMG experience debilitating muscle weakness, resulting in impaired mobility, speech, swallowing, vision and respiratory function. Efgartigimod is a human IgG1 antibody Fc fragment engineered for increased binding affinity to neonatal Fc receptor. The neonatal Fc receptor blockade by efgartigimod competitively inhibits endogenous IgG binding, leading to decreased IgG recycling and increased degradation resulting in lower IgG concentration.MethodsThe safety and efficacy of efgartigimod were evaluated in the ADAPT study. Key efficacy outcome measures included Myasthenia Gravis Activities of Daily Living (MG‐ADL) and Quantitative Myasthenia Gravis (QMG) scores. Efgartigimod demonstrated significant improvement in both the MG‐ADL and QMG scores. This post hoc analysis aimed to determine whether all subdomains of MG‐ADL and QMG improved with efgartigimod treatment. Individual items of MG‐ADL and QMG were grouped into four subdomains: bulbar, ocular, limb/gross motor and respiratory. Change from baseline over 10 weeks in each subdomain was calculated for each group.ResultsGreater improvements from baseline were seen across MG‐ADL subdomains in participants treated with efgartigimod compared with placebo. These improvements were typically observed 1 to 2 weeks after the first infusion and correlated with reductions in IgG. Similar results were observed across most QMG subdomains.ConclusionsThese post hoc analyses of MG‐ADL and QMG subdomain data from ADAPT suggest that efgartigimod is beneficial in improving muscle function and strength across all muscle groups, leading to the observed efficacy in participants with gMG.

Real-World Case Series of Efgartigimod for Japanese Generalized Myasthenia Gravis: Well-Tailored Treatment Cycle Intervals Contribute to Sustained Symptom Control

“…However, substantial relief from long-term diplopia and external ophthalmoplegia highlights the necessity of considering not just clinical measurements but also symptomatic relief affecting the patients’ QOL, such as extraocular muscle palsy [ 25 ]. This finding aligns with that reported previously, suggesting that efgartigimod treatment notably improves ocular symptoms in patients with MG [ 26 ]. Similarly, Case 4 underscores the drug’s potential in managing bulbar symptoms.…”

Efgartigimod is a new option for the treatment of thymoma associated myasthenia gravis: A case report

“…About 68 % of those in the efgartigimod group were MG-ADL responders, with an odds ratio of 4.95, compared to placebo group. Primary and post hoc analyses of ADAPT trials both demonstrated greater improvements were seen across MG-ADL and QMG in efgartigimod group [ 1 , 2 ]. These improvements and reductions of IgG were typically observed over 1 to 2 weeks after the first infusion.…”

“…The clinical benefits of efgartigimod are durable and tolerable, with most adverse events being mild to moderate [ 1 ]. Furthermore, efgartigimod provides consistent clinical improvements of muscle function and strength across all muscle groups [ 2 ]. Efgartigimod is also called as “plasma exchange in a bottle” [ 3 ].…”