FDA Expands Efgartigimod Approval to All Adult Generalized Myasthenia Gravis Patients
The FDA expanded efgartigimod approval to all adult generalized myasthenia gravis serotypes. Phase 3 ADAPT SERON met its primary endpoint and showed no new safety signals.
The FDA expanded the label for efgartigimod to cover all adult generalized myasthenia gravis serotypes, including anti-MuSK-Ab positive, anti-LRP4-Ab positive, and triple seronegative patients. The expansion closes an exclusion gap for the roughly 20% of generalized myasthenia gravis patients who lack detectable AChR antibodies.
The ADAPT SERON trial was built specifically around the seronegative population, making it the largest prospective study of non-AChR-Ab generalized myasthenia gravis patients to date. The primary endpoint, MG-ADL improvement at week 4, was met at p=0.0068, with a mean 3.35-point change from baseline in the overall study population.
The benefit held across subsequent treatment cycles and across each individual serotype subgroup. Triple seronegative patients, approximately 10% of all generalized myasthenia gravis cases, were included in the study.
The safety profile showed no new signals relative to the established AChR-Ab positive experience. A label covering all adult serotypes lets physicians act on clinical diagnosis alone, removing a meaningful access delay for patients who had been managing on immunosuppressants and symptom control while waiting for evidence to catch up to their disease biology.