Switching from plasma exchange to Vyvgart well tolerated, effective
Convenience of infusion therapy noted among advantages for MG patients
Switching from maintenance therapeutic plasma exchange (TPE) to Vyvgart (efgartigimod) appeared to be well tolerated and effective for people with myasthenia gravis (MG), a short report suggests.
“The good clinical response of this patient cohort, together with greater accessibility and convenience of infusion-based therapy, are notable advantages of efgartigimod over TPE,” the researchers wrote in “Retrospective review of patients with myasthenia gravis switched from plasma exchange therapy to efgartigimod treatment,” which was published in Muscle & Nerve.
MG occurs when the immune system mistakenly attacks proteins involved in nerve-muscle communication, leading to symptoms of muscle weakness and fatigue.
TPE, a type of blood-filtering treatment, is often used to treat MG exacerbations, or episodes of sudden disease worsening. In some patients, particularly those who don’t respond to other therapies, it’s also used as a maintenance therapy.
As part of the procedure, blood is removed from a patient and its liquid component, called plasma, which contains the self-reactive antibodies that drive MG, is filtered out. The plasma is then replaced with a fluid that doesn’t contain antibodies and infused back into the patient.
Vyvgart is a monoclonal antibody designed to block the neonatal Fc receptor, a protein that normally helps stabilize antibodies circulating in the bloodstream, and thereby reduce the levels of MG-causing antibodies. It was approved for generalized MG in the U.S. in 2021.
“Since the FDA approval of efgartigimod, clinicians have started to switch patients who were treated with maintenance TPE to efgartigimod and have gained clinical experience with this therapeutic transition,” wrote researchers at the University of North Carolina who retrospectively analyzed the medical records of seven MG patients who switched from maintenance TPE to into-the-vein (intravenous) Vyvgart at their institution.
Benefits of Vyvgart in myasthenia gravis
Five patients were women and two were men, ranging in age from 24-80. The duration of TPE treatment before switching to Vyvgart ranged from four months to 10 years, while treatment with Vyvgart lasted for one to 13 months, or just over a year.
Along with maintenance TPE, six patients were treated with medications to curb the activity of the immune system, including prednisone, mycophenolate mofetil (sold as CellCept), azathioprine (sold as Imuran, among other names), and a combination of rituximab (sold as Rituxan, among other names) and mycophenolate mofetil.
All the patients completed an initial four-week cycle in which they received weekly infusions of Vyvgart at 10 mg/kg. Additional cycles varied based on clinical symptoms, duration of treatment response, and side effects.
Three patients remained on a single maintenance dose of Vyvgart given once monthly, while two others were maintained on two weekly infusions with two-week intervals between cycles to reduce the risk of infection. Another patient continued receiving weekly infusions for four weeks, with four-week intervals between cycles, and another completed a second cycle of four weekly infusions.
Treatment outcomes were evaluated using the MG-Activities of Daily Living (MG-ADL), a patient-reported scale commonly used to assess symptom severity, and the MG Manual Muscle Testing (MG-MMT) scale to grade the strength of muscle groups.
In six patients, MG-ADL scores improved after the first four doses of Vyvgart. In five of these patients, MG-ADL scores remained stable at the most recent visit, but worsened in the other. In one patient, MG-ADL scores worsened after the switch, but remained stable at the most recent visit.
Three patients had MG-ADL scores of 0 or 1 at the most recent visit, indicating they’d reached a status of showing minimal symptoms.
The MG-MMT score and the MGFA-Post Intervention Status (MGFA-PIS), which assesses treatment efficacy based on symptoms and the use of MG therapies, improved after the switch in six patients and were unchanged in another.
In five patients, the median levels of antibodies were lower while they were on Vyvgart compared with maintenance TPE.
The most common side effects after switching included uncomplicated infections, such as urinary tract and upper respiratory infections. The infection rate and severity appeared to be reduced by changes in the frequency of Vyvgart dosing.
“Overall, the patients who were changed from maintenance TPE to efgartigimiod tolerated this switch well with stable to improved measures of MG disease activity,” wrote the researchers, who said “long-term observation” is needed to better understand the long-term efficacy and side effects in these patients.
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