Just 16 months after securing its first FDA green light for Imaavy, Johnson & Johnson has expanded the monoclonal antibody’s label to include another rare disease, bringing the potential blockbuster into the treatment of warm autoimmune hemolytic anemia (wAIHA).
The FDA has cleared Imaavy for adults and adolescents aged 12 and older with wAIHA who are currently receiving corticosteroids or have previously been treated with them. The disorder is a rare and potentially fatal condition in which harmful immunoglobulin G (IgG) autoantibodies attack and destroy red blood cells.
What Imaavy Does
Imaavy is an immuno-selective neonatal fragment crystallizable receptor (FcRn) inhibitor that introduces a different treatment approach to wAIHA. It is the first therapy approved for the condition that specifically targets the IgG autoantibodies believed to be responsible for driving the disease.
Karen Jones, President and Executive Director of wAIHA Warriors, described the condition as one that can leave patients dealing with persistent exhaustion and uncertainty. She explained that people may experience periods of improvement before their hemoglobin levels fall again, bringing back severe fatigue and forcing them to restart the cycle of managing their illness.
Data That Helped With the FDA Green Light
The FDA decision was supported by Phase 2/3 data demonstrating a statistically significant and sustained improvement in red blood cell counts among patients receiving Imaavy. The 115-participant study assigned patients to two different Imaavy dose groups or placebo. After 24 weeks, the proportion of patients receiving the 30 mg/kg dose who achieved sustained hemoglobin (Hgb) responses was approximately three times higher than the rate observed in the placebo group.
J&J Global Immunology Therapeutic Area Head David Lee said the approval establishes Imaavy as the first approved therapy for wAIHA and could significantly change how the disease is managed, particularly among patients whose condition remains inadequately controlled. He added that the milestone strengthens J&J’s commitment to developing advanced treatments for diseases driven by alloantibodies and autoantibodies.
How the Company Got Hold of Imaavy
Johnson & Johnson obtained Imaavy through its $6.5 billion acquisition of Momenta Pharmaceuticals in 2020. Five years later, the FDA approved the drug for generalized myasthenia gravis (gMG), making it the third FcRn blocker cleared for that indication. UCB’s Rystiggo and argenx’s Vyvgart were approved previously, in 2023 and 2021, respectively.
Johnson & Johnson has not yet disclosed Imaavy’s sales figures, although the company has estimated that the drug could eventually generate peak annual revenue of at least $5 billion.
The wAIHA approval could be the first of several additional indications for Imaavy. The antibody is currently being tested in Phase 3 studies for fetal neonatal alloimmune thrombocytopenia, Sjogren’s disease and hemolytic disease of the fetus and newborn. All three programs have received FDA fast-track accreditation.
J&J is also evaluating Imaavy in idiopathic inflammatory myopathy, systemic lupus erythematosus and chronic inflammatory demyelinating polyneuropathy. The company previously abandoned plans in 2024 to develop the drug as part of a combination treatment for rheumatoid arthritis.
Imaavy has received its first FDA label expansion, giving Johnson & Johnson’s medicine a new indication in warm autoimmune hemolytic anemia (wAIHA). The FDA approved Imaavy on August 24, 2026, for adults and pediatric patients aged 12 and older with wAIHA who are currently or previously treated with corticosteroids.
A New Option for Patients
The expanded indication provides physicians with a targeted treatment option for people living with warm autoimmune hemolytic anemia. The condition can cause the immune system to mistakenly destroy healthy red blood cells, potentially leading to anemia, fatigue, weakness, and other complications.
How the Treatment Works
The medicine belongs to a class of therapies known as FcRn blockers. By interfering with the neonatal Fc receptor pathway, it reduces the amount of circulating IgG antibodies. This approach is particularly relevant in diseases where harmful antibodies contribute to tissue or blood-cell damage.
Clinical Evidence
The regulatory decision was supported by data from the ENERGY clinical program. Researchers evaluated whether treatment could produce sustained improvements in hemoglobin levels and other measures of disease activity.
The results suggested that some patients experienced relatively rapid improvements, while continued treatment helped maintain the response over time.
Potential Impact on Treatment
Warm autoimmune hemolytic anemia can be difficult to manage, particularly when patients do not respond adequately to corticosteroids or experience disease recurrence. A targeted therapy could provide another approach for patients who require longer-term disease control.
Broader Development Strategy
The medicine is being evaluated across several antibody-mediated and autoimmune conditions. Expanding development into additional diseases could increase its clinical utility if future trials demonstrate meaningful benefits.
Imaavy Strengthens J&J’s Immunology Portfolio
For Johnson & Johnson, the expanded Imaavy label strengthens its immunology portfolio and creates another potential growth opportunity. The company has previously identified the medicine as having potential peak sales of $5 billion or more if it succeeds across multiple indications.
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