A real-life experience with eculizumab and efgartigimod in generalized myasthenia gravis patients

Abstract

Introduction: Eculizumab, a complement active antibody, and efgartigimod, an Fc fragment that blocks neonatal Fc receptor, are both approved to treat generalized myasthenia gravis (gMG) patients. The objective of this study is to describe the clinical response to both treatments in a real-life setting.

Methods: We collected baseline and follow-up clinical data using the Myasthenia Gravis-Activities of Daily Living (MG-ADL), and Quantitative Myasthenia Gravis (QMG). We included 63 patients, 32 treated with eculizumab and 31 with efgartigimod. Of the efgartigimod-treated patients, 22 were anti-acetylcholine receptor antibody-positive (AChR-Ab +) and 9 were AChR-Ab- (3 MuSK-Ab + and 6 seronegative).

Results: Both treatments showed similar efficacy relative to the MG-ADL scale reduction (p = 0.237). Efgartigimod had a similar effect on both AChR-Ab + and AChR-Ab- (p = 0.280). Eculizumab was superior to efgartigimod relative to the QMG score reduction for the entire dataset (p = 0.003) and was more likely to achieve a clinical response at the QMG compared to efgartigimod (OR 1.373; p = 0.016). Steroid-sparing effect was higher for eculizumab than efgartigimod ( - 16.7 vs - 5.2 mg of the baseline daily dose at follow-up; p = 0.001). Mean speed of prednisone reduction was - 13.1 mg of the daily dose for each month of follow-up for eculizumab-treated patients and - 3.2 for efgartigimod (p = 0.001). We found three serious events, all not related to treatment in the investigator's opinion. One eculizumab-treated patient experienced a severe pneumonia and died despite treatment.

Conclusions: Our study provides evidence that eculizumab and efgartigimod can be used in clinical practice to reduce disability in gMG patients. Eculizumab-treated patients had a higher QMG response and steroid sparing effect. Efgartigimod may offer a more flexible schedule due to its cyclical use, no need for vaccination, and efficacy in AChR-Ab- patients.

Keywords: Innovative; MG-ADL; Observational; QMG; Real-world evidence; Seronegative.

Fig. 1

MG-ADL response in Eculizumab and Efgartigimod-treated patients. MG-ADL Myasthenia Gravis Activities of Daily Living scale. Error bars show the standard error mean

Fig. 2

MG-ADL response in Efgartigimod-treated AChR-Ab + and AChR-Ab- patients. MG-ADL  Myasthenia Gravis Activities of Daily Living scale, AChR-Ab +  anti-acetylcholine receptor antibody positive, AChR-Ab- anti-acetylcholine receptor antibody negative. Error bars show the standard error mean

Fig. 3

Responder Rate at the MG-ADL and QMG scales. A MG-ADL responder rate at different time points. B QMG responder rate at different time points. MG-ADL Myasthenia Gravis Activities of Daily Living scale, QMG Myasthenia Gravis quantitative scale. *p < 0.05; **p < 0.01

Fig. 4

QMG response in Eculizumab and Efgartigimod-treated patients. QMG Myasthenia Gravis quantitative scale. *p < 0.05; **p < 0.01. The week 4 interval refers to Efgartigimod-treated patients and week 5 to Eculizumab-treated patients

Fig. 5

Clinical Events during Eculizumab and Efgartigimod treatment. QMG Myasthenia Gravis quantitative scale. *p= 0.043, excluding anti-acetylcholine receptor antibody-negative patients p = 0.185

Fig. 6

Treatment retention during follow-up with Eculizumab and Efgartigimod

Fig. 7

Corticosteroid dose reduction during Eculizumab and Efgartigimod treatment. Treatment effect for all treated patients was in favor of Eculizumab ( – 11.5 mg/day; F = 11.728; p = 0.001). ***p < 0.001