Efgartigimod for generalized myasthenia gravis: A multicenter real-world cohort study in China

Abstract

Objective: Efgartigimod, a neonatal Fc receptor antagonist, facilitates antibody degradation including pathogenic IgGs. The ADAPT study demonstrated the tolerability and efficacy of efgartigimod in the treatment of generalized myasthenia gravis (gMG). However, very limited evidence is available for the Chinese population, and it remains inconclusive about which kind of patients are selected to preferentially receive efgartigimod in real-world settings.

Methods: This multicenter cohort study included gMG patients treated at 14 neuromuscular reference centers in China. The Myasthenia Gravis Activities of Daily Living (MG-ADL) score, immunosuppressants, and the incidence of treatment-emergent adverse events (TEAEs) were prospectively collected.

Results: Of the 1640 gMG admitted between September and December 2023, 61 (3.7%) received efgartigimod for at least one treatment cycle. Among them, 56 cases (92%) were anti-AChR antibody-positive, 4 were anti-MuSK antibody-positive, and 1 was seronegative. Thymoma-associated myasthenia gravis accounted for most cases (44%, 27 out of 61). The principal causes of efgartigimod initiation included MG acute exacerbation (MGAE) (48%, 29 out of 61) and myasthenic crisis (MC) (15%, 9 out of 61). Clinically meaningful improvement was rapidly achieved in 97% (58 out of 61) of patients at 1.3 ± 0.7 weeks. By week 12, the MG-ADL score reduced to 3.8 ± 4.1 (baseline:10.5 ± 5.2) for all participants, while it reduced to 4.0 ± 4.7 for MGAE and 3.8 ± 4.2 for MC, respectively. All but one TMG patient required no additional rescue therapies after efgartigimod initiation. 11.5% (7 out of 61) reported ≥1 TEAEs.

Interpretation: This multicenter cohort study demonstrated the efficacy of efgartigimod in rapid control of gMG. Patients with MGAE or MC would benefit from efgartigimod treatment.

Figure 1

The changes in MG‐ADL scores of gMG stratified by the serotypes of antibody and initiation disease status. MG‐ADL score changes in AChR+ gMG (n = 56) and AChR− gMG (n = 5) (A). MG‐ADL score changes in gMG with mild/moderate disease (n = 23), MGAE (n = 29), and MC (n = 9) (B). AChR, acetylcholine receptor; gMG, generalized myasthenia gravis; MC, myasthenic crisis; MG‐ADL, Myasthenia Gravis Activities of Daily Living; MGAE, myasthenia gravis acute exacerbation.

Figure 2

The proportion of gMG patients with different MG‐ADL scores at baseline, 4 weeks, 8 weeks, and 12 weeks after efgartigimod initiation. gMG, generalized myasthenia gravis; MG‐ADL, Myasthenia Gravis Activities of Daily Living.

Figure 3

MG‐ADL score changes in 3 patients who did not exhibit rapid response to efgartigimod within 4 weeks. MG‐ADL, Myasthenia Gravis Activities of Daily Living.