Efgartigimod Alfa Provides Much-Needed Treatment Options for Patients With Generalized Myasthenia Gravis

Efgartigimod alfa injection (Vyvgart; argenx), initially approved by the FDA in 2021, is a neonatal Fc receptor blocker indicated for the treatment of generalized myasthenia gravis in adult patients who are anti-acetylcholine receptor (AChR) antibody positive. Efgartigimod alfa is a human IgG1 antibody fragment that binds to the neonatal Fc receptor, causing the reduction of the circulating IgG levels in the body.¹

Syringe and a vial for injection | Image credit: Trsakaoe | stock.adobe.com

The approval was based on findings from the global phase 3 ADAPT trial, published in The Lancet Neurology in July 2021. The trial met its primary end point, showing that significantly more anti-AChR antibody positive participants with generalized myasthenia gravis were responders on the MG-ADL scale following treatment with efgartigimod alfa compared with placebo (68% vs 30%; p<0.0001). Responders were defined as having at least a 2-point reduction on the MG-ADL scale sustained for 4 or more consecutive weeks during the first treatment cycle.¹

This medication comes in an infusion dosage form and the recommended dose is 10 mg/kg to be administered intravenously over the course of 1 hour. The dosing is usually administered once weekly for 4 weeks. For patients weighing 120 kg or more, the recommended dose is 1200 mg per infusion. Because this medication is an infusion, it should be diluted with 0.9% sodium chloride injection through a 0.2 micron in-line filter. The medication is supplied in 400 mg in 20ml or 20 mg/ml single dose vial form.²

Treatment with efgartigimod alfa should be delayed for patients with active infection. Those who have had infusion reactions should be evaluated prior to their next dose and patients who have had severe hypersensitivity reactions should avoid the medication or be monitored very closely, if the next dose is recommended by the provider. The most common adverse effects seen with efgartigimod alfa include respiratory tract infections, headache, and urinary tract infection.²

The FDA has also approved a coformulation of efgartigimod alfa and hyaluronidase (Vyvgart Hytrulo; argenx). Hyaluronidase increases the permeability of the subcutaneous tissue and is an endoglycosidase. This formulation is indicated for the treatment of adult patients with generalized myasthenia gravis who are anti-acetylcholine receptor antibody positive, as well as for chronic inflammatory demyelination polyneuropathy (CIDP).³

Dosing for efgartigimod alfa and hyaluronidase is 1008 mg/11,200 units in once weekly injections for 4 weeks. The dosing and route may differ from patient to patient based on individual needs. Some of the most common adverse effects seen with efgartigimod alfa and hyaluronidase are injection site reactions, rash, erythema, pruritus, bruising, pain, urticaria, headache and urinary tract infections.³ Importantly, efgartigimod alfa is administered via infusion whereas efgartigimod alfa and hyaluronidase administered via subcutaneous injection by a health care professional.³

Pharmacists can provide extra resources for patients undergoing either of these treatments, including explanations of the therapy options for the patients, the course of therapy, and what patients can expect. There are also other self-education resources, such as My Vyvgart path, which can support patient understanding of the insurance process. Such resources can help fill the financial gaps that regular health coverage may not cover for the patients in need of Vyvgart.³

With these new treatment options for patients with AchR antibody-positive myasthenia gravis and CIDP, patients have more options to chose from. Importantly, these treatments can also be personalized based on patient needs and preferences (either infusion or injection).

REFERENCES

1. argenx Announces US Food and Drug Administration (FDA) Approval of Vyvgart (efgartigimod alfa-fcab) in Generalized Myasthenia Gravis. Business Wire. December 17, 2021. Accessed August 28, 2024. https://www.businesswire.com/news/home/20211217005641/en\

2. Efgartigimod alfa-fcab (Vyvgart); prescribing information. Updated December 2021. Accessed August 28, 2024. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/761195s000lbl.pdf

3. Vyvgart. Accessed August 28, 2024. https://vyvgarthcp.com/gmg