Vyvgart (efgartigimod alfa-fcab) for myasthenia gravis

What is Vyvgart for myasthenia gravis?

Vyvgart (efgartigimod alfa-fcab) is an approved infusion therapy for adults with generalized myasthenia gravis (gMG), regardless of which disease-causing antibodies are present, if any. It is administered intravenously — via infusions into the bloodstream — to ease disease severity.

The medication belongs to a class of therapies called FcRn blockers. The neonatal Fc receptor (FcRn) normally stabilizes and prevents the breakdown of immunoglobulin G (IgG) antibodies, a class that includes self-reactive antibodies linked to myasthenia gravis (MG). By blocking it, Vyvgart accelerates the clearance of MG-causing antibodies from the bloodstream, helping to ease disease symptoms.

Argenx sells Vyvgart. The company also markets another formulation, Vyvgart Hytrulo, which can be self-administered via under-the-skin injections. These two medications were the first therapies approved in the U.S. for all adults with gMG, regardless of antibody status.

Therapy snapshot

Who can take Vyvgart?

In the U.S., Vyvgart is approved for adults with gMG. In the European Union and Canada, it is approved for adults with gMG who test positive for antibodies against the acetylcholine receptor (AChR), the most common disease-causing antibody.

Per the U.S. prescribing label, Vyvgart is contraindicated (should not be used) by people with a history of serious immune reactions (hypersensitivity) to any of its ingredients or efgartigimod alfa products, including Vyvgart Hytrulo.

How is Vyvgart administered?

A healthcare provider administers Vyvgart via an hourlong intravenous infusion. The treatment is initially given once a week for four weeks. Additional four-week treatment cycles may subsequently be given based on clinical response.

The recommended dose per infusion is 10 mg/kg body weight, or 1,200 mg for patients weighing 120 kg (about 265 pounds) or more.

Patients will be monitored throughout each infusion and for one hour afterward for signs of an immune reaction.

Vyvgart in clinical trials

Vyvgart’s approvals for adults with gMG were mainly supported by two Phase 3 clinical trials. The ADAPT trial (NCT03669588) supported the initial approval for AChR antibody-positive patients, while the ADAPT SERON study (NCT06298552) supported the approval for AChR antibody-negative patients.

• ADAPT involved 167 adults with gMG, most of whom had anti-AChR antibodies, who received Vyvgart at its now-approved dosing regimen or a placebo along with standard treatments. Significantly more AChR antibody-positive patients on Vyvgart than on placebo experienced meaningful improvements in patient- and clinician-rated measures of disease severity after the first treatment cycle.
• ADAPT SERON included 119 AChR antibody-negative patients, including those who tested positive for other MG-causing antibodies and those who tested negative for any known disease-related antibodies (triple seronegative). As in the AChR antibody-positive population, Vyvgart was associated with meaningful reductions in disease severity after the first treatment cycle compared with a placebo.

Vyvgart side effects

The most common side effects associated with Vyvgart include:

• respiratory and urinary tract infections
• headache

Vyvgart also carries warnings for potential serious side effects that require careful monitoring. These include:

• infections
• hypersensitivity reactions, including anaphylaxis, a life-threatening systemic reaction
• infusion-related reactions

If these events occur, Vyvgart may need to be paused or discontinued, depending on the severity.

Vyvgart should not be initiated in a person with an active infection, and individuals should receive all age-appropriate vaccines recommended by their doctor before starting treatment.