Johnson & Johnson's nipocalimab, an investigational FcRn blocker, has been granted Priority Review by the U.S. Food and Drug Administration (FDA) for the treatment of generalized myasthenia gravis (gMG) in antibody-positive patients. This designation underscores the potential of nipocalimab to address a significant unmet need in the treatment of gMG, a chronic, autoantibody-driven disease affecting an estimated 700,000 people worldwide.
The FDA's Priority Review is based on data from the Phase 3 Vivacity-MG3 study, a 24-week, double-blind, placebo-controlled trial that evaluated the efficacy and safety of nipocalimab in adults with gMG. The study included patients with anti-AChR, anti-MuSK, and anti-LRP4 positive antibodies. Results demonstrated that nipocalimab, when added to standard of care (SOC), led to a statistically significant and clinically meaningful improvement in disease control compared to placebo plus SOC.
Key Findings from the Vivacity-MG3 Study
The Vivacity-MG3 study met its primary endpoint, demonstrating a statistically significant improvement in the Myasthenia Gravis Activities of Daily Living (MG-ADL) score over 24 weeks. Patients receiving nipocalimab plus SOC achieved a significantly greater reduction in MG-ADL response (≥2-point improvement from baseline) compared with placebo plus SOC (p=0.0213).
"We welcome the FDA's decision to grant Priority Review for the treatment of generalized myasthenia gravis, which underscores the need for additional treatment options in a broad population of people living with gMG," said Katie Abouzahr, M.D., Vice President, Autoantibody Portfolio and Maternal Fetal Immunology Disease Area Leader at Johnson & Johnson Innovative Medicine. "We are committed to working closely with the FDA to help bring nipocalimab as a potential treatment to certain patients living with gMG, and we especially thank the participants in the Phase 2 and 3 studies. If approved, nipocalimab has the potential to treat gMG in antibody positive individuals, including anti-AChR, anti-MuSK, and/or anti-LRP4."
Understanding Generalized Myasthenia Gravis
Myasthenia gravis (MG) is an autoimmune disease characterized by the immune system mistakenly attacking the neuromuscular junction, disrupting communication between nerves and muscles. This leads to fluctuating muscle weakness, affecting activities such as limb movement, eye function, chewing, swallowing, speech, and breathing. In approximately 85% of cases, the disease generalizes, leading to gMG.
Nipocalimab: A Novel FcRn Blocker
Nipocalimab is an investigational monoclonal antibody designed to bind with high affinity to block the neonatal Fc receptor (FcRn). By blocking FcRn, nipocalimab aims to reduce levels of circulating immunoglobulin G (IgG) antibodies, including autoantibodies, without causing broad immunosuppression. This targeted approach has the potential to address the underlying cause of gMG while preserving other immune functions.
Regulatory Progress and Future Outlook
In addition to the FDA Priority Review, Johnson & Johnson has also submitted a Marketing Authorisation Application (MAA) to the European Medicines Agency (EMA) seeking approval of nipocalimab in gMG. The FDA is expected to make a final decision in the third quarter of 2025. If approved, nipocalimab would face competition from existing FcRn blockers such as Argenx’s Vyvgart and UCB’s Rystiggo.
Johnson & Johnson is also evaluating nipocalimab across multiple immunology and neuroscience indications in separate mid- to late-stage clinical studies, including chronic inflammatory demyelinating polyneuropathy (CIDP), hemolytic disease of the fetus and newborn (HDFN), warm autoimmune hemolytic anemia (wAIHA), Sjogren's disease, systemic lupus erythematosus, and rheumatoid arthritis.
