Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Jun;14(3):e200276.
doi: 10.1212/CPJ.0000000000200276. Epub 2024 Mar 25.

Therapeutic Responses to Efgartigimod for Generalized Myasthenia Gravis in Japan

Shigeaki Suzuki  1 , Akiyuki Uzawa  1 , Yuriko Nagane  1 , Masayuki Masuda  1 , Shingo Konno  1 , Tomoya Kubota  1 , Makoto Samukawa  1 , Kei Ishizuchi  1 , Daiki Tokuyasu  1 , Hideo Handa  1 , Manato Yasuda  1 , Naoki Kawaguchi  1 , Takashi Kimura  1 , Yasushi Suzuki  1 , Takamichi Sugimoto  1 , Naoya Minami  1 , Masanori P Takahashi  1 , Hiroyuki Murai  1 , Kimiaki Utsugisawa  1
Affiliations

Therapeutic Responses to Efgartigimod for Generalized Myasthenia Gravis in Japan

Shigeaki Suzuki et al. Neurol Clin Pract. 2024 Jun.

Abstract

Background and objectives: Efgartigimod, which has been well tolerated and efficacious in individuals with generalized myasthenia gravis (MG), is available in Japan not only for the treatment of anti-acetylcholine receptor-positive (AChR+) but also anti-muscle-specific receptor tyrosine kinase (MuSK+) and seronegative generalized MG. We report details of the use of efgartigimod for generalized MG in clinical practice in Japan.

Methods: We included patients with generalized MG in the 2021 survey of Japan Myasthenia Gravis Registry (JAMG-R) study group who received an initial cycle of efgartigimod between May and September 2022. We defined "responders" as patients who achieved a score ≥2 points for MG activities of daily living (MG-ADL) in the first treatment cycle. The MG composite and the Revised scale of the 15-item Myasthenia Gravis-Quality of Life scale (MG-QOL15-r) were also evaluated.

Results: Of 1,343 JAMG-R patients, 36 (2.7%) started efgartigimod (female 68%, age 53 years). Their serologic profiles were as follows: AChR+, n = 19 (53%); MuSK+, n = 6 (17%); and seronegative, n = 11 (31%). Twenty-six patients (72%) had refractory MG. There were 81 cycles of efgartigimod during the 26-week observation in 34 patients (average, 2.4 cycles). The mean interval between cycles was 5.9 weeks. A continuous 4-weekly infusion of efgartigimod was performed in 65 (80%) of 81 cycles. In the first cycle, the MG-ADL score of the 34 patients decreased significantly from 10.5 ± 4.3 to 6.9 ± 5.1 (p = 0.003). Similarly, the mean MG composite and MG-QOL15-r decreased from 18.4 ± 13.6 to 11.8 ± 9.6 (p = 0.004) and from 19.2 ± 6.3 to 14.2 ± 8.3 (p = 0.007), respectively. Twenty-one (62%) patients were responders. Therapeutic responses were observed in the subsequent cycles. The duration of effectiveness of efgartigimod was varied among the responders; 4 responders had only a single effective cycle. Significant improvement was observed in the MuSK+ patients. Prednisolone dose of 7 patients was reduced. Our examination of the patients' postintervention status revealed that 6 patients achieved minimal manifestations. COVID-19 occurred in 5 patients. We failed to detect clinical or laboratory findings associated with responders.

Discussion: Efgartigimod can be considered for the treatment of patients with generalized MG who do not achieve minimal manifestations, with a broad flexibility of patient selection and treatment schedules.

PubMed Disclaimer

Conflict of interest statement

S. Suzuki has received personal fees from Alexion Pharmaceuticals, Argenx, UCB Pharma, the Japan Blood Products Organization, and Asahi Kasei Medical. A. Uzawa has received honoraria from Alexion Pharmaceuticals and Argenx. Y. Nagane has received speaker honoraria from Argenx, Alexion Pharmaceuticals, and the Japan Blood Products Organization. M. Masuda and S. Konno declare no potential conflicts of interest related to this article. T. Kubota has received honoraria for lectures from Alexon Pharmaceuticals, Argenx, and UCB Pharma. M. Samukawa, K. Ishizuchi, D. Tokuyasu, H. Handa, M. Yasuda, N. Kawaguchi, T. Kimura, Y. Suzuki, T. Sugimoto, and N. Minami declare no potential conflicts of interest related to this article. M.P. Takahashi reports unrestricted research grants from Japan Blood Products Organization, Astellas Pharma, Mitsubishi Tanabe Pharma, and Pfizer outside the submitted work and honoraria for lectures from Argenx, Alexion Pharmaceuticals, and UCB Pharma. H. Murai has served as a paid consultant for Alexion, AstraZeneca Rare Disease, Argenx, and UCB and has received speaker honoraria from the Japan Blood Products Organization and Chugai Pharmaceutical and research support from the Ministry of Health, Labour and Welfare, Japan. K. Utsugisawa has served as a paid consultant for UCB Pharma, Argenx, Janssen Pharma, Viela Bio, Chugai Pharma, Hanall BioPharma, and Mitsubishi Tanabe Pharma and has received speaker honoraria from Argenx, Alexion Pharmaceuticals, and the Japan Blood Products Organization. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp.

Figures

Figure 1
Figure 1. Study Flow
Study flow (A) and autoantibody profiles (B). AChR+ = anti–acetylcholine receptor–positive; JAMG-G = Japan Myasthenia Gravis Registry; MuSK+ = anti–muscle-specific receptor tyrosine kinase-positive.
Figure 2
Figure 2. Cycles of Efgartigimod
Time courses of efgartigimod in 34 patients with generalized MG. Numbers = the numbers of cycles of efgartigimod treatment. AChR+ = anti–acetylcholine receptor–positive; MuSK+ = anti–muscle-specific receptor tyrosine kinase-positive; C = COVID-19; e = eculizumab; g = intravenous immunoglobulin; m = intravenous high-dose methylprednisolone; N = nonresponder; R = responder.
Figure 3
Figure 3. Therapeutic Responses to Efgartigimod
Changes in the patients' myasthenia gravis activities of daily living. AChR+ = anti–acetylcholine receptor–positive; MuSK+ = anti–muscle-specific receptor tyrosine kinase-positive.
Figure 4
Figure 4. Outcome of Patients
Changes in the patients' postintervention status. Black circles indicate patients with minimal symptom expression. AChR+ = anti–acetylcholine receptor–positive; MuSK+ = anti–muscle-specific receptor tyrosine kinase–positive.
See this image and copyright information in PMC

References

    1. Punga AR, Maddison P, Heckmann JM, Guptill JT, Evoli A. Epidemiology, diagnostics, and biomarkers of autoimmune neuromuscular junction disorders. Lancet Neurol. 2022;21(2):176-188. doi:10.1016/S1474-4422(21)00297-0 - DOI - PubMed
    1. Narayanaswami P, Sanders DB, Wolfe G, et al. . International consensus guidance for management of myasthenia gravis: 2020 update. Neurology. 2021;96(3):114-122. doi:10.1212/WNL.0000000000011124 - DOI - PMC - PubMed
    1. Vanoli F, Mantegazza R. Antibody therapies in autoimmune neuromuscular junction disorders: approach to myasthenic crisis and chronic management. Neurotherapeutics. 2022;19(3):897-910. doi:10.1007/s13311-022-01181-3 - DOI - PMC - PubMed
    1. Schneider-Gold C, Hagenacker T, Melzer N, Ruck T. Understanding the burden of refractory myasthenia gravis. Ther Adv Neurol Disord. 2019;12:1756286419832242. doi:10.1177/1756286419832242 - DOI - PMC - PubMed
    1. Tran C, Biswas A, Mendoza M, Katzberg H, Bril V, Barnett C. Performance of different criteria for refractory myasthenia gravis. Eur J Neurol. 2021;28(4):1375-1384. doi:10.1111/ene.14675 - DOI - PubMed