Johnson & Johnson Wins Imaavy Approval In Warm Autoimmune Hemolytic Anemia, Adding A First FDA-Approved Option

Johnson & Johnson has won FDA approval for Imaavy in warm autoimmune hemolytic anemia, giving patients with the rare blood disorder the first therapy specifically approved for the condition. The decision, announced after Monday’s market close, covers use of nipocalimab in patients age 12 and older with wAIHA.

The approval extends the reach of a drug that was initially approved last year for generalized myasthenia gravis. It also gives J&J a new approved use for an FcRn-targeting antibody in a disease where standard care has relied on corticosteroids and immunosuppressants that broadly suppress the immune system rather than directly targeting the autoantibodies driving the illness.

The Data

In wAIHA, pathogenic autoantibodies destroy red blood cells. The disease is termed “warm” because that process occurs at normal body temperature, in contrast to cold agglutinin disease, which develops in cold temperatures. In severe cases, the resulting burden on the heart and lungs can become life threatening.

Imaavy is a monoclonal antibody designed to bind to neonatal Fc receptor, or FcRn, a protein that keeps pathogenic immunoglobulin G antibodies circulating in the body. By blocking FcRn, more IgG antibodies are degraded instead of being recycled into circulation.

J&J’s regulatory submission was based on a Phase 2/3 study that enrolled 115 participants. According to the company, the trial showed a statistically significant durable hemoglobin response measured at 24 weeks versus placebo. The most common adverse reactions were peripheral edema, diarrhea, and fever. Full results were presented in June at the annual meeting of the European Hematology Association.

The Commercial Picture

The approval gives J&J an entry into a rare disease setting with no prior FDA-approved therapy, but the larger strategic importance may be what it says about the company’s ambitions for Imaavy across immunology. J&J has projected the product could achieve $5 billion in peak sales, reflecting its view that the mechanism can support a wide range of indications beyond its first launch in myasthenia gravis.

Sales are still small enough that J&J does not break Imaavy out separately in its financial reports. Even so, the company has pointed to Imaavy and the oral plaque psoriasis drug Icotyde, approved in March, as contributors to revenue growth alongside other immunology assets that are also not yet disclosed separately. Together, those assets generated $150 million in global revenue in the first half of 2026, compared with $9 million in the same period last year.

Imaavy was originally developed by Momenta Pharmaceuticals, which J&J acquired for $6.5 billion in 2020. The company continues to run a broad clinical program spanning rheumatologic diseases, rare autoantibody diseases, and maternal fetal diseases mediated by maternal alloantibodies. That breadth matters because this approval does more than open one orphan market; it gives J&J another regulatory proof point for a platform asset it is trying to extend across multiple immunology categories.