Abstract Details

Title Safety and Effectiveness of Efgartigimod in Japanese Patients With Generalized Myasthenia Gravis by Serological Profiles: Analysis of Post-marketing Surveillance

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P9 - Poster Session 9 (5:00 PM-6:00 PM)

Poster/Presentation
Number 9-006

Objective To assess the safety and effectiveness of efgartigimod for intravenous infusion (efgartigimod-IV) in patients with generalized myasthenia gravis (gMG) by serological profiles in real-world settings.

Background Efgartigimod is a human IgG1 Fc-fragment engineered to block the neonatal Fc receptor. Efgartigimod-IV is approved in Japan for gMG regardless of serological profiles, i.e., anti-acetylcholine receptor antibody positive (AChR-Ab+), anti-muscle-specific receptor kinase antibody positive (MuSK-Ab+) or double seronegative; anti-LRP4 antibody is not usually tested. Upon the direction by Japan regulatory authorities, post-marketing surveillance (PMS) is performed.

Design/Methods Patients with gMG who received efgartigimod-IV between May 2022 and September 2023 were registered for the PMS. Effectiveness was evaluated by Myasthenia Gravis Activities of Daily Living (MG-ADL) total score.

Results The safety analysis set consisted of 469 patients: 57.1% (n=268) AChR-Ab+, 13.4% (n=63) MuSK-Ab+, and 29.4% (n=138) double-seronegative. Overall, adverse drug reactions and serious adverse drug reactions were reported in 22.6% and 4.2% of patients, respectively. Generally, safety was consistent with the known safety profile of efgartigimod, and no specific signals were observed in any of the serological profiles. The effectiveness analysis set consisted of 307 patients with a similar composition ratio of serological profiles to the safety analysis set. Overall, mean MG-ADL total score decreased from 7.2 to 4.2 after three weeks from the first administration: −3.0 points (standard deviation: 2.98, p< 0.001). Significant score decreases were observed in each serological profile; −3.0 for AChR-Ab+, −3.7 for MuSK-Ab+, and −2.8 for double-seronegative. For oral glucocorticoid dose, the percentage of patient with ≤5 mg/day increased from 27.7% to 40.8%, and that with >15 mg/day decreased from 15.5% to 7.3% during one year treatment. Substantial oral glucocorticoid dose changes were observed regardless of serological profiles.

Conclusions In real-world settings, efgartigimod-IV was well tolerated and effective in patients with gMG regardless of serological profiles: AChR-Ab+, MuSK-Ab+, and double-seronegative.

Authors/Disclosures
Hirofumi Teranishi PRESENTER	Mr. Teranishi has received personal compensation for serving as an employee of argenx.
Ryohei Aoyagi, PhD	Mr. Aoyagi has received personal compensation for serving as an employee of argenx. Mr. Aoyagi has stock in argenx.
Daisuke Harada, PhD (argenx Japan K.K.)	Mr. Harada has received personal compensation for serving as an employee of argenx K.K..
Mitsuru Watanabe (Kyushu University)	Mitsuru Watanabe has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alexion Pharma, Mitsubishi Tanabe Pharma, UCB Japan. Mitsuru Watanabe has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Alexion Pharma, Argenx, UCB Japan, Novartis Pharma, Biogen Japan, Mitsubishi Tanabe Pharma, Chugai Pharmaceutical, Viatris, and Daiichi Sankyo. The institution of Mitsuru Watanabe has received research support from Japan. Mitsuru Watanabe has received publishing royalties from a publication relating to health care.

��ɫ��

��ɫ��