The US Food and Drug Administration (FDA) has approved Vyvgart (efgartigimod alfa) and Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase) for the treatment of adult patients who have anti-MuSK-Ab positive, anti-LRP4-Ab positive, and/or triple seronegative generalized myasthenia gravis (gMG). The medication was previously approved to treat patients with anti-AChR-Ab positive gMG.
gMG is a chronic autoimmune neuromuscular disease characterized by weakness of the skeletal muscles. Common symptoms include weakness of the muscles that control the eye and eyelid, facial expressions, chewing, talking, and swallowing. The condition results from a defect in the transmission of nerve impulses to muscles due to the presence of antibodies against the acetylcholine receptor. The exact reason this occurs is not known.
Efgartigimod alfa is a first-in-class human IgG1 antibody fragment that binds to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG autoantibodies. Vyvgart Hytrulo is a subcutaneous combination of efgartigimod alfa and recombinant human hyaluronidase PH20 (rHuPH20) that allows for subcutaneous injection delivery.
The new approval is based on data from the randomized, double-blind, placebo-controlled, multi-center phase 3 ADAPT SERON clinical trial. The study included patients with nondetectable anti-acetylcholine receptor antibodies (AChR-Ab) across three serotypes: anti-MuSK-Ab positive, anti-LRP4-Ab positive, and triple seronegative.
Patients showed clinically meaningful improvements in disease activity across all three serotypes and the primary endpoint was met, illustrating that patients treated with efgartigimod achieved significant improvement in MG Activities of Daily Living (MG-ADL) total score, compared to placebo, at week 4.
In the overall population, mean change from baseline in patients treated with efgartigimod was a 3.35-point improvement in MG-ADL score at week 4. Improvements in MG-ADL and Quantitative Myasthenia Gravis (QMG) scores were observed across subsequent treatment cycles in the overall population and in all serotypes.
Additionally, efgartigimod was well tolerated across serotypes with a safety profile consistent with what has been established in patients with anti-AChR-Ab positive gMG.
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To learn more about gMG and other rare autoimmune conditions, visit https://checkrare.com/diseases/autoimmune-autoinflammatory-disorders/