Eculizumab Associated With Clinical Improvement in Generalized Myasthenia Gravis

In patients with acetylcholine receptor–positive generalized myasthenia gravis (AChR+ gMG), treatment with eculizumab is associated with clinical improvements at 1 to 3 months. It also had a favorable safety profile even when combined with other immunosuppressants. These are the findings of a retrospective study published in the journal Muscle & Nerve.

Researchers identified patients through their neuromuscular practices at Massachusetts General Hospital and Brigham and Women’s Hospital — both located in Boston, Massachusetts. Patients included in the current study needed to be at least 18 years of age to be diagnosed with AChR+ gMG, to have received 1 dose or more of eculizumab following US Food and Drug Administration (FDA) approval, and to have had 1 follow-up or more prior to December 10, 2021. Data on all patients were abstracted from electronic medical records.

Study outcomes included MG Foundation of America Post Intervention Status(MGFA-PIS), MGFA Clinical Classification (MGFA-CC), MG-Activities of Daily Living (MG-ADL), concurrent use of immunotherapy, and adverse events.

A total of 12 patients (6 women, 6 men) were identified. The mean patient age at eculizumab initiation was 57.4 years (range, 21.0-77.0 years). The mean interval between a diagnosis of MG and initiation of eculizumab treatment was 7.8 years (range, 0.16-28.0 years). Overall, 8 of the patients had refractory MG, and 4 had a history of thymoma and thymectomy. Among patients, a mean of 3.2 (range, 2.0 to 5.0) immunomodulatory therapies had been tried previously. The mean follow-up duration was 18.0 months (range, 2.0-21.6 months).

Results of the study showed that clinical improvement occurred quickly. At 1 month following eculizumab initiation, MGFA-CC improved in 83% of patients by 1 grade or more and MGFA-PIS improved in 80% of participants. The mean MG-ADL score decreased from 8.7 to 2.8 at 1 month, with the score remaining at up to 3.5 over 1.5 years.

At 1.5 years, participants’ mean daily prednisone dose decreased from 22.5 mg to 7.2 mg. Overall, 5 of 7 patients discontinued maintenance therapy with intravenous immunoglobulin or plasma exchange. None of the patients experienced meningococcal infections, including meningitis. All of the adverse events reported were mild, including headache, myalgia/arthralgia, leg edema, dizziness, nausea, localized inflammation at the injection site, and pruritus of the torso. None of the adverse events were associated with treatment discontinuation.

Limitations of the present study include its retrospective design and small sample size, with patients enrolled from 2 associated tertiary care institutions. Additionally, a placebo effect or the effects of other treatments cannot be ruled out.

According to the researchers, “This study helps provide realistic expectations of change in MG symptoms with eculizumab in clinical practice.”

Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.