Efficacy and Safety of Weekly Subcutaneous Efgartigimod for Myasthenia Gravis: Yuebing Li, MD, PhD

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“This treatment has been approved by the FDA for patients with generalized myasthenia gravis who test positive for the receptor antibody. Therefore, this specific patient population is well-suited for this alternative. It's important to note that this is a subcutaneous continuous form, not an intravenous one, and should be administered by a healthcare provider, not the patient. While a brief monitoring period is required, this method proves more convenient for patients compared with intravenous formulations."

Efgartigimod (Argenx), a human immunoglobulin (IgG)1 antibody Fc-fragment, is designed to block the neonatal Fc receptor and reduce IgG autoantibody levels. The treatment was originally approved in an intravenous (IV) formulation in December 2021 for patients with generalized myasthenia gravis (gMG) based on significant findings from the phase 3 ADAPT trial (NCT03669588). In the original analysis, the agent was shown to be well-tolerated and efficacious, meeting its primary end point of improvement in Myasthenia Gravis–Activities of Daily Living item scores relative with the placebo (67.7% vs 29.7%; P <.0001).¹

Recently presented at the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) meeting, held November 1-4, in Phoenix, Arizona, new interim data from the open label extension (OLE) of the ADAPT-SC+ trial (NCT04818671) assessing a subcutaneous (SC) version of efgartigimod PH20 demonstrated improvements in daily function in treated patients with gMG. Overall, the findings showed that multiple cycles of the treatment were well tolerated and showed strong efficacy, which were consistent with the results observed in using the IV formulation in the ADAPT/ADAPT+trial.²

During the meeting, lead author Yuebing Li, MD, PhD, a neurologist in the neuromuscular center at the Cleveland Clinic, sat down in an interview with NeurologyLive® to discuss how the 2 forms of efgartigimod compared with each other in terms of safety and efficacy. He also shared the implications of the FDA approval for patients with gMG, and how it influences the current treatment landscape. Additionally, Li spoke about the ways in which the continuous treatment cycle of efgartigimod impacts the individualization of treatment plans for patients with gMG, and how does relates to the reduction of other immunotherapies.

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REFERENCES
1. FDA Approves New Treatment for Myasthenia Gravis. News release. FDA. Published December 17, 2021. Accessed November 14, 2023. https://www.fda.gov/news-events/press-announcements/fda-approves-new-treatment-myasthenia-gravis
2. Li Y, Howard JF Jr, Li G, et al. Long-Term Safety, Tolerability, and Efficacy of Subcutaneous Efgartigimod PH20 in Patients With Generalized Myasthenia Gravis: Interim Results of the ADAPT-SC+ Study. Presented at: American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) meeting; November 1-4, 2023; Phoenix, AZ. Abstract 222.