The US Food and Drug Administration has expanded the indication for efgartigimod alfa-fcab (VYVGART) and efgartigimod alfa with hyaluronidase-qvfc (VYVGART Hytrulo) to include all adult patients with generalized myasthenia gravis (gMG), regardless of antibody status, according to a press release from argenx. The approval includes patients who are anti-acetylcholine receptor antibody (AChR-Ab) positive, anti-muscle-specific tyrosine kinase antibody (MuSK-Ab) positive, anti-low-density lipoprotein receptor-related protein 4 antibody (LRP4-Ab) positive, and triple seronegative.

The decision was supported by findings from the Phase 3 ADAPT SERON trial, a randomized, double-blind, placebo-controlled study that enrolled 119 adults with anti-AChR antibody-negative gMG across North America, Europe, China, and the Middle East. Patients treated with efgartigimod demonstrated statistically significant improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) scores compared with placebo at week 4. The treatment group achieved a mean 3.35-point improvement from baseline in MG-ADL total score. Improvements in MG-ADL and Quantitative Myasthenia Gravis scores were observed in the overall population across anti-MuSK-Ab-positive, anti-LRP4-Ab-positive, and triple-seronegative subgroups during subsequent treatment cycles.

“MG leads to debilitating muscle weakness, causing challenges with vision, movement, speech, swallowing, and even breathing. Although many [myasthenia gravis] patients have detectable AChR-Ab, roughly 20% do not, making diagnosis and management especially difficult,” noted James F. Howard Jr, MD, of The University of North Carolina at Chapel Hill School of Medicine.

Generalized myasthenia gravis is a chronic autoimmune neuromuscular disorder associated with pathogenic immunoglobulin G antibodies targeting the neuromuscular junction, resulting in muscle weakness and fatigue. Patients who are triple seronegative do not have detectable antibodies against AChR, MuSK, or LRP4 and have historically had limited representation in clinical studies.

ADAPT SERON and  VYVGART was well tolerated regardless of serotype, with a safety profile that aligned with its established record in anti-AChR-Ab positive gMG. Common side effects included respiratory tract infection, headache, urinary tract infection, and injection-site reactions with the subcutaneous formulation.

Source: Argenx