General Information

Vyvgart (efgartigimod alfa-fcab) is a neonatal Fc receptor blocker.

Vyvgart is specifically indicated for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive.

Vyvgart is supplied as an injection for intravenous administration. Because Vyvgart causes transient reduction in IgG levels, immunization with live-attenuated or live vaccines is not recommended during treatment with Vyvgart. Evaluate the need to administer age appropriate immunizations according to immunization guidelines before initiation of a new treatment cycle with Vyvgart.

Dilute Vyvgart prior to administration. The recommended dosage of Vyvgart is 10 mg/kg administered as an intravenous infusion over one hour once weekly for 4 weeks. In patients weighing 120 kg or more, the recommended dose of Vyvgart is 1200 mg (3 vials) per infusion. Administer subsequent treatment cycles based on clinical evaluation. The safety of initiating subsequent cycles sooner than 50 days from the start of the previous treatment cycle has not been established. If a scheduled infusion is missed, Vyvgart may be administered up to 3 days after the scheduled time point. Thereafter, resume the original dosing schedule until the treatment cycle is completed.

Clinical Trials Results

FDA approval of Vyvgart was based on results from the global Phase 3 ADAPT trial. The randomized, double-blind, placebo-controlled trial enrolled 167 patients. Patients were eligible regardless of anti-acetylcholine receptor antibody status, if they had a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of at least 5 (>50% non-ocular) and were on a stable dose of at least one treatment for generalized myasthenia gravis. The patients were randomly assigned to efgartigimod (10 mg/kg) or matching placebo, administered as four infusions per cycle (one infusion per week), repeated as needed depending on clinical response no sooner than 8 weeks after initiation of the previous cycle. The primary endpoint was proportion of acetylcholine receptor antibody-positive patients who were MG-ADL responders (≥2-point MG-ADL improvement sustained for ≥4 weeks) in the first treatment cycle.

The ADAPT trial met its primary endpoint, demonstrating that significantly more anti-AChR antibody positive gMG patients were responders on the MG-ADL scale following treatment with Vyvgart compared with placebo (68% vs. 30%; p<0.0001). Responders were defined as having at least a two-point reduction on the MG-ADL scale sustained for four or more consecutive weeks during the first treatment cycle. There were additionally significantly more responders on the Quantitative Myasthenia Gravis (QMG) scale following treatment with Vyvgart compared with placebo (63% vs. 14%; p<0.0001). Responders were defined as having at least a three-point reduction on the QMG scale sustained for four or more consecutive weeks during the first treatment cycle.