Efgartigimod (marketed as Vyvgart) has shown promising results in patients with seronegative myasthenia gravis (MG) participating in the ADAPT SERON clinical trial, according to a recent press release.
Efgartigimod is an FcRn blocker. It binds to the neonatal Fc receptor and inhibits it, thereby reducing plasma levels of immunoglobulin G (IgG), which plays a key role in the pathophysiology of MG.
In 2021, efgartigimod was approved for patients with anti-acetylcholine receptor (AChR) antibody-positive MG. Roughly 80% of patients have this type of MG. The remaining 20% are AChR-seronegative but may present antibodies to muscle-specific kinase (MuSK), to low-density lipoprotein receptor-related protein 4 (LRP4), or to none of these proteins. The later is called seronegative MG.
Seronegative patients have historically been excluded from clinical studies. Some evidence suggests that these patients have a higher disease burden, in addition to greater unmet treatment needs. Furthermore, there are currently no approved therapies for anti-LRP4 or triple-seronegative patients.
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The Phase 3 ADAPT SERON trial was a randomized, double-blind, placebo-controlled, multicenter study enrolling adults with AChR-seronegative generalized MG (gMG) across North America, Europe, China and the Middle East.
The study was divided into two parts: Part A randomized participants 1:1 to receive four once-weekly intravenous (IV) infusions of efgartigimod or placebo, followed by a five-week follow-up period for the primary analysis. Part B was an open-label extension with fixed cycles and clinician-guided retreatment starting from cycle three onward.
The results showed that patients receiving efgartigimod experienced meaningful improvements compared to those receiving placebo. The safety profile was consistent with that observed in AChR-positive MG patients.
“The results of the ADAPT SERON study, the largest study to date of AChR-antibody seronegative gMG, confirm that VYVGART now has the potential to be a targeted, effective, safe, and necessary treatment for patients living with gMG, regardless of autoantibody status,” said Dr. James F. Howard Jr., the principal investigator for the ADAPT SERON trial. “Paired with our existing knowledge, these data demonstrate that pathogenic IgGs are underlying drivers of gMG across patient subtypes. This is a critical advancement in the management of this debilitating and unpredictable disease for patients with limited treatment options.”
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