Efgartigimod in Very Late-Onset Myasthenia Gravis: Efficacy and Safety

13 Apr 20264 min read0 viewsJournal Feed

GIST (Key Takeaways)

Background. Myasthenia gravis (MG) is an autoimmune disease. Recently, the prevalence of very late-onset MG (VLOMG; onset ≥ 65 years) has rapidly increased.
The treatment of VLOMG groups is associated with several challenges, including multiple comorbidities, polypharmacy, and immunosenescence. Efgartigimod, which is the first approved neonatal Fc receptor (FcRN) antagonist, is reported to rapidly ameliorate MG symptoms with a favorable safety profile. Thus, efgartigimod is a potential novel therapeutic for VLOMG.Objective.
This study retrospectively analyzed the clinical data of patients with VLOMG treated with efgartigimod at our center over the past two years to assess its long-term efficacy and safety. Methods. This study retrospectively enrolled 62 patients with VLOMG who received at least one efgartigimod treatment cycle.
The primary efficacy outcomes were the proportion of patients achieving minimum symptom expression (MSE) and the reduction in glucocorticoid dosage.

Efficacy signals for efgartigimod in very-late-onset MG: study design and patient experience:

The report summarizes a retrospective evaluation of efgartigimod use in adults with very late-onset myasthenia gravis (VLOMG), defined as onset at age 65 or older.
The aim was to assess longer-term efficacy and safety in a real-world, center-based cohort over a two-year period.

Design: Retrospective case series from a single center.
Population: 62 patients with VLOMG who received at least one cycle of efgartigimod.
Treatment exposure: Patients completed varying numbers of treatment cycles; 37 completed one cycle, 10 completed two cycles, and 15 completed three or more cycles.

Primary outcomes:
Proportion achieving minimum symptom expression (MSE) by study end; observed cumulative achievement rate was 41.9% (26 of 62).
Change in glucocorticoid dosage from baseline after treatment.
Secondary outcomes:
Changes from baseline in MG-Activities of Daily Living (MG-ADL) scores.
Changes in Quantitative Myasthenia Gravis (QMG) scores.
Changes in MG Quality of Life 15-item revised (MG-QoL15r) scores.
Functional shifts in specific muscle groups (ocular, bulbar, respiratory, axial, limb).

Limb/axial function showed significant improvement in 15 patients (P < 0.05).

Across all measured scales (MG-ADL, QMG, MG-QoL15r), post-treatment scores were significantly improved relative to baseline, with statistical significance reported for each of the one-, two-, and three-or-more-cycle groups (P < 0.001, P < 0.01, and P < 0.05, respectively, depending on the outcome).
Subgroup analyses indicated significant functional improvements in bulbar, limb (including axial), and ocular muscles after treatment in 37 patients (P < 0.01 for these domains).
Glucocorticoid-sparing signal: Post-treatment glucocorticoid dosages decreased significantly compared with baseline among patients across the one-, two-, and ≥3-cycle cohorts (P < 0.0001, P < 0.05, and P < 0.05, respectively).

Adverse events were limited but present: one patient developed an allergic rash, one reported gastric discomfort, and two experienced headache during efgartigimod treatment.

The design is retrospective and single-center, with no randomized comparator arm.
The overall sample is modest in size, and the heterogeneity of prior therapies and comorbidities typical of VLOMG is not exhaustively detailed here.
The study reports statistical significance for several outcomes but does not provide numeric effect sizes or confidence intervals within this summary.

The authors interpret the data as indicating that efgartigimod can improve symptom burden and quality of life in VLOMG and may permit reduction of glucocorticoids in the short term.
Uncertainty remains regarding long-term durability beyond the observed cycles, comparative effectiveness versus alternative therapies, and broader safety beyond the reported adverse events.