From the FDA Drug Label
Efgartigimod alfa-fcab is a human immunoglobulin G1 (IgG1) -derived Fc fragment (fragment, crystallized) of the za allotype. VYVGART (efgartigimod alfa-fcab) injection is a sterile, preservative free, clear to slightly opalescent, colorless to slightly yellow solution supplied in a single-dose vial for infusion after dilution.
Vyvgart (efgartigimod) is a human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG.
- It is supplied as a sterile, preservative-free solution for infusion after dilution.
- The molecular weight of efgartigimod alfa-fcab is approximately 54 kDa 1.
From the Research
Vyvgart (efgartigimod) is a neonatal Fc receptor antagonist indicated for the treatment of generalized myasthenia gravis (gMG) in adults who are acetylcholine receptor (AChR) antibody positive.
Overview of Vyvgart
Vyvgart (efgartigimod) is approved for both intravenous (IV) and subcutaneous (SC) use, with the IV formulation being associated with significant and clinically meaningful improvements in myasthenia gravis symptoms and reductions in disease burden, as seen in a pivotal phase III trial 2. The beneficial effects of IV efgartigimod were reproducible, durable, and maintained over the long term, also improving health-related quality of life (HRQOL).
Mechanism of Action and Efficacy
Efgartigimod works by binding to the neonatal Fc receptor (FcRn), preventing it from recycling IgG antibodies and leading to their elimination from circulation, which reduces the autoimmune attack on neuromuscular junctions and improves muscle function 3. In the double-blind, placebo-controlled phase 3 ADAPT trial, efgartigimod alfa significantly and rapidly reduced disease burden and improved muscle strength and quality of life compared with placebo, with clinical benefits being durable and reproducible 3.
Safety and Tolerability
Efgartigimod was generally well tolerated, with most adverse events being mild to moderate in severity, including headache and infections (with IV efgartigimod) and injection-site reactions (with SC efgartigimod PH20) 2. Although further long-term data are required, IV and SC formulations of efgartigimod provide effective, generally well-tolerated, and flexible treatment options for adults with AChR Ab+ gMG.
Clinical Use
The use of Vyvgart (efgartigimod) is recommended for adults with generalized myasthenia gravis who are anti-acetylcholine receptor antibody positive, given its efficacy in reducing disease burden and improving quality of life, as demonstrated in clinical trials 2, 3. Patients should be monitored for infections during treatment, as the medication can increase susceptibility by reducing immunoglobulin levels. Unlike other treatments for myasthenia gravis, Vyvgart specifically targets the disease mechanism without broadly suppressing the immune system, making it an important option for patients who don't respond adequately to conventional therapies.