Frank Vinluan , 2025-05-01 19:50:00
A Johnson & Johnson autoimmune disease medicine that’s a relative latecomer in its drug class can now compete in its first FDA-approved indication with a label that covers a broader patient population than products already available from Argenx and UCB.
The FDA has approved the J&J drug, known in development as nipocalimab, as a treatment for generalized myasthenia gravis (gMG). The regulatory decision announced Wednesday could be the first of several for this antibody, which the pharmaceutical giant has projected could reach $5 billion in peak sales across multiple indications. The new J&J product, administered as an intravenous infusion every two weeks, will be marketed under the brand name Imaavy.
In gMG, the immune system makes autoantibodies that attack proteins involved in the communication between nerves and muscles. Patients develop severe muscle weakness as well as problems speaking and swallowing. J&J says an estimated 100,000 people in the U.S. are living with gMG; there are about 700,000 patients worldwide.
Imaavy leverages a cell’s a built-in mechanisms for managing proteins, including antibodies. Proteins are routinely brought into cells where they either go to a cellular system that degrades them or they are recycled into circulation. Antibodies bound to neonatal Fc receptor (FcRn) are recycled. The antibody in Imaavy is designed to block FcRn, an approach intended increase degradation of disease-driving autoantibodies. The approval in gMG covers adults and children age 12 and older who are positive for either the AChR or MuSK autoantibodies that drive the disease.
In Phase 3 testing in adults, J&J reported Imaavy reduced autoantibody levels by up to 75% from the first dose. This reduction was sustained throughout the 24-week study. Results were published in February in The Lancet Neurology.
“Patients experienced substantial symptom relief and lasting disease control that translated into better daily function and did not fade over 24 weeks in the pivotal Vivacity-MG3 study,” Dr. Nicholas Silvestri, professor of neurology at the University of Buffalo, said in statement included in J&J’s announcement of the approval. “Having a treatment that delivers this level of durable symptom stability is a meaningful step forward for managing a complex and unpredictable disease like gMG, and to have it in both AChR+ and MuSK+ adults and pediatric patients 12 years and older brings an additional FcRn treatment to a broader range of patients.”
In the Phase 2/3 test of Imaavy in pediatric patients that is still ongoing, J&J has reported a 69% reduction in disease-driving autoantibodies over 24 weeks. The ability to treat pediatric gMG patients sets Imaavy apart from its rivals.
Argenx’s Vyvgart, approved by the FDA in 2021, was the first FcRn-blocking drug to reach gMG patients. This antibody fragment addresses only disease driven by AChR autoantibodies. The agency signed off on a subcutaneously injectable version of the drug, Vyvgart Hytrulo, in 2023. Both products are approved only for use in adults.
UCB markets an FDA-approved FcRn blocker called Rystiggo, a once weekly infusion that addresses both AChR and MuSK antibodies. The Belgian company has another FDA-approved gMG drug, Zilbrysq. This drug blocks a complement system protein that drives disease and its approval in gMG covers only patients positive for AChR antibodies. The 2023 approvals of both UCB products permit their use only in adults.
Imaavy was the main asset of Momenta Pharmaceuticals, which J&J acquired in 2020 for $6.5 billion. Momenta was developing the antibody for multiple autoimmune indications, and J&J is continuing that strategy. Beyond rare autoantibody disorders, J&J is developing this drug for alloantibody diseases of pregnancy as well as prevalent rheumatology disorders such as lupus and rheumatoid arthritis, according to an investor presentation. The company is currently planning 10 indications for the drug.
J&J’s $5 billion peak sales projection for Imaavy spans all potential indications. But if the product succeeds in expanding its approved uses, it could also bump up against the FcRn-blocking drugs from Argenx and UCB. Both companies are conducting clinical research that could support expansion of their respective products to other indications. Last summer, the FDA approved Argenx’s Vyvgart Hytrulo as a new treatment for chronic inflammatory demyelinating polyneuropathy (CIDP). This rare disease in which autoantibodies attack the nerves is one of the indications that J&J is pursuing with Imaavy.
Photo by Johnson & Johnson
