Abstract Details

Title Assessing Efgartigimod Dosing Patterns and Myasthenia Gravis Activities of Daily Living Outcomes in Clinical Practice: Results From a Large Patient Support Program Database in the United States

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P11 - Poster Session 11 (11:45 AM-12:45 PM)

Poster/Presentation
Number 9-020

Objective

Evaluate dosing patterns and Myasthenia Gravis Activities of Daily Living (MG-ADL) responses following efgartigimod initiation among patients with generalized myasthenia gravis (gMG) in the United States (US).

Background Efgartigimod is an engineered human Fc-fragment that is approved globally for treatment of anti-acetylcholinesterase receptor antibody positive (and regardless of antibody status in Japan) gMG. Each efgartigimod cycle consists of 1 infusion each week for 4 weeks; intervals between cycles vary based on individual response, enabling adaptability for heterogeneous phenotypes.

Design/Methods US adults (aged ≥18 years) with gMG who initiated efgartigimod by April 1, 2025, and enrolled in the My VYVGART Path patient support program were included. Efgartigimod infusion dates and MG-ADL scores were captured through phone contact. Patients with both baseline (pre-efgartigimod) and ≥4 MG-ADL scores captured post-efgartigimod initiation were included. To assess dosing patterns, weeks between treatment cycles were analyzed. To analyze outcomes, lowest MG-ADL scores post-efgartigimod initiation were compared with baseline scores for each patient, then averaged at the population level.

Results

2648 patients were included; mean (SD) age was 67.5 (15) years and 1132 (43%) were female. Among all efgartigimod cycles, 4 weeks was the most common interval (28% of all identified intervals). At the population level, mean (SD) baseline MG-ADL score was 8.2 (3.7). Mean largest MG-ADL improvement from baseline after efgartigimod initiation was 5.8 points, with 91% of patients experiencing clinically meaningful improvement (CMI; 2-point improvement in MG-ADL). At any time after efgartigimod initiation, 83% (n=2185) achieved mild disease state of MG-ADL ≤4, and 45% (n=1188) achieved minimal symptom expression (MSE; MG-ADL of 0 or 1).

Conclusions Among patients who initiated efgartigimod in clinical practice, intervals between cycles were most commonly 4 weeks, with substantial proportion achieving CMI and almost half achieving MSE. Limitations include some potential selection bias with patients enrolled in the PSP.

Authors/Disclosures
Pushpa Narayanaswami, MD, MBBS, FAAN (Beth Israel Deaconess Medical Center) PRESENTER	Dr. Narayanaswami has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for UCB. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving as a Consultant for CVS. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi. Dr. Narayanaswami has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Janssen. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx USA. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Narayanaswami has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Narayanaswami has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for NMD pharma. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for EMD-Serono (Merck usa). Dr. Narayanaswami has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Immuneabs. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Viridian. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cabaletta-Bio. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Immunovant. Dr. Narayanaswami has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Dianthus. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Cartesian. Dr. Narayanaswami has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Vor Bio. Dr. Narayanaswami has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Muscle and Nerve, Wiley. Dr. Narayanaswami has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology. Dr. Narayanaswami has or had stock in Dr. Reddys laboratories.Dr. Narayanaswami has or had stock in Doximity. The institution of Dr. Narayanaswami has received research support from Alexion. The institution of Dr. Narayanaswami has received research support from NIH. The institution of Dr. Narayanaswami has received research support from Argenx. The institution of Dr. Narayanaswami has received research support from Cabaletta Bio. Dr. Narayanaswami has received publishing royalties from a publication relating to health care. Dr. Narayanaswami has a non-compensated relationship as a Member, Finance Committee with AANEM that is relevant to AAN interests or activities.
Martina Orlovic, PhD	Dr. Orlovic has received personal compensation for serving as an employee of argenx. Dr. Orlovic has stock in argenx.
Cynthia Qi (argenx)	Cynthia Qi has received personal compensation for serving as an employee of argenx.
Ratna K. Bhavaraju-Sanka, MD, FAAN (UT Health Science Center @ San Antonio)	Dr. Bhavaraju-Sanka has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Argenx. Dr. Bhavaraju-Sanka has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Amgen.
Evan Smith, PhD	Dr. Smith has nothing to disclose.
Matt Jefferson	Matt Jefferson has received personal compensation for serving as an employee of argenx. Matt Jefferson has stock in argenx.
Deborah Gelinas, MD (ARGENX)	Dr. Gelinas has received personal compensation for serving as an employee of argenx. Dr. Gelinas has stock in argenx.
Rohit Menon	Rohit Menon has received personal compensation for serving as an employee of ZS Associates.
Mai Sato, PhD	Dr. Sato has received personal compensation for serving as an employee of ZS Associates.
Gil I. Wolfe, MD, FAAN (Univ. At Buffalo, SUNY)	Dr. Wolfe has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Grifols. Dr. Wolfe has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Alexion. Dr. Wolfe has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for ArgenX. Dr. Wolfe has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for UCB/Ra. Dr. Wolfe has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Janssen. Dr. Wolfe has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Cartesian. Dr. Wolfe has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Grifols. The institution of Dr. Wolfe has received research support from UCB/Ra. The institution of Dr. Wolfe has received research support from Immunovant. The institution of Dr. Wolfe has received research support from Roche. Dr. Wolfe has received personal compensation in the range of $0-$499 for serving as a Advisor with FDA Advisory Panel for Cellular, Tissue and Genetic Therapies.

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