The US Food and Drug Administration (FDA) has approved efgartigimod ( Vyvgart, argenx), a first-in-class, targeted treatment for adults with generalized myasthenia gravis (gMG) who are positive for the anti-acetylcholine receptor (AChR) antibody.
“There are significant unmet medical needs for those suffering from myasthenia Gravis, as well as many other rare diseases,” Billy Dunn, MD, director, Office of Neuroscience, FDA Center for Drug Evaluation and Research, said in a press release.
Dunn said that this approval is “an important step in giving patients a novel therapy option and underscores agency’s determination to provide new treatment options for patients suffering from rare diseases available.”
The rare and severe neuromuscular disorder autoimmune to GMG can result in debilitating and possibly life-threatening muscle weakness as well as diminished independence and quality of life.
Patients with gMG are likely to have immunoglobulin G antibodies (IgG) that are directed at skeletal muscles nicotinic and Acetylcholine.
Efgartigimod is an antibody fragment that is designed to reduce IgG antibodies that cause pathogens and block the process of recycling IgG in patients suffering from gMG.
The novel agent binds to the neonatal Fc receptor (FcRn) which is found in all the body and plays an important role in rescuing IgG antibodies degradation. Blocking FcRn decreases IgG antibody levels.
As reported by Medscape Medical News,efgartigimod was well-tolerated and efficacious in the phase 3, controlled, randomized placebo-controlled ADAPT trial, which involved in 187 patients with gMG, regardless of the acetylcholine-receptor antibody status. All were afflicted with an Myasthenia Gravis Activities of Daily Living (MG-ADL) score of at minimum 5 (> 50 percent non-ocular) with an indefinite dose of at least one MG drug.
For 26 weeks for 26 weeks, 84 patients received efgartigimod at 10 mg/kg, and 83 received placebo. Both treatments were administered as four infusions per cycle , with one infusion per week. The procedure was repeated as required, dependent on the clinical response, but no sooner than 8 weeks after initiation of the previous cycle.
Treatment with efgartigimod decreased the burden of disease and improved strength and quality of life in patients with gMG across four MG-specific scales. These benefits were also noted early, and were durable and reproducible.
The results were published in June in Lancet Neurology .
“Important New Advance”
Efgartigimod is a “very rapidly acting drug relative to other treatments that could take up to 4 6 to 10 months before they start to take effect and the adverse effects are similar to placebo,” principal investigator James Howard, Jr, MD, Department of Neurology, University of North Carolina at Chapel Hill, told Medscape Medical News back in June.
FDA granted efgartigimod fast-track and orphan drug designations.
“People with gMG need new treatment options that target the root causes of the disease and are supported by clinical research,” Howard stated in an official news release following approval.
This approval “represents an important step forward for families and patients affected by this debilitating disease. Howard stated that this treatment could reduce the burden of disease caused by gMG, and also changing the way we treat the disease.
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