FDA Approves Johnson & Johnson’s Imaavy as First Treatment for Rare Warm Autoimmune Hemolytic Anemia

A rare and potentially fatal form of anemia has secured its first FDA-approved treatment with Johnson & Johnson’s drug, which targets the underlying mechanisms of the disease.

The regulatory decision, announced after Monday’s market close, approves nipocalimab (brand name Imaavy) for treating patients age 12 and older with warm autoimmune hemolytic anemia (wAIHA). This represents an expanded approval for the intravenously infused drug, which initially received approval last year for generalized myasthenia gravis. With potential applications across a broad spectrum of immunological conditions, J&J projects the product could achieve $5 billion in peak sales.

In wAIHA, the anemia develops when pathogenic autoantibodies destroy red blood cells. The condition is termed “warm” because this destruction occurs at normal body temperature, distinguishing it from cold agglutinin disease, which develops in cold temperatures. In severe cases, the disease’s burden on the heart and lungs can become life threatening.

The standard treatment for wAIHA has traditionally involved corticosteroids and immunosuppressants that broadly suppress the immune system without specifically targeting the autoantibodies driving the disease. Imaavy is a monoclonal antibody designed to bind to neonatal Fc receptor (FcRn), a protein responsible for maintaining pathogenic immunoglobulin G antibodies (IgG) in circulation. By blocking FcRn, more IgG antibodies are degraded rather than recycled back into circulation.

J&J’s regulatory submission for Imaavy in wAIHA was based on data from a Phase 2/3 study enrolling 115 participants. Results demonstrated a statistically significant durable hemoglobin response measured at 24 weeks compared to placebo. The most common adverse reactions were peripheral edema, diarrhea, and fever. Full results were presented in June during the annual meeting of the European Hematology Association.

“As the first therapy approved for wAIHA, Imaavy has the potential to redefine the management of warm autoimmune hemolytic anemia, particularly for those with uncontrolled disease,” said David Lee, J&J Global Immunology Therapeutic Area Head, in a prepared statement.

Sales for Imaavy are not yet large enough for J&J to break out separately in its financial reports. However, the company highlights this product along with the new oral plaque psoriasis drug Icotyde, approved in March, as drivers of revenue growth alongside other immunology assets. These immunology assets accounted for $150 million in global revenue in the first half of 2026 compared to $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. J&J maintains a broad ongoing clinical program for Imaavy, spanning rheumatologic diseases, rare autoantibody diseases, and maternal fetal diseases mediated by maternal alloantibodies.

Image: virusowy, Getty Images

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