FDA Approves J&J's Imaavy for Warm Autoimmune Hemolytic Anemia

The Food and Drug Administration has approved Imaavy (nipocalimab-aahu) for warm autoimmune hemolytic anemia (wAIHA) in adults and children 12 and older who are currently or were previously treated with corticosteroids, Johnson & Johnson announced on August 24. The decision followed a Priority Review.

The company said the approval marks the first time a therapy has been shown safe and effective specifically for wAIHA, a rare disease in which immunoglobulin G (IgG) autoantibodies attach to and destroy red blood cells. Until now, patients have been treated with corticosteroids and immunosuppressants that act on the whole immune system, BioPharm International reported.

Imaavy is an antibody that blocks the neonatal Fc receptor (FcRn), which lowers the level of circulating IgG antibodies. It is already approved for generalized myasthenia gravis in adults and children 12 and older with certain antibodies, so wAIHA is its second indication.

The ENERGY trial

The approval is based on ENERGY (NCT04119050), a randomized, double-blind, placebo-controlled Phase 2/3 study in which 115 adults with wAIHA were randomized roughly equally to one of two nipocalimab dose schedules or placebo for 24 weeks, according to J&J.

The primary endpoint was durable hemoglobin response, defined as a hemoglobin level of at least 10 g/dL and a rise of at least 2 g/dL from baseline sustained for at least 28 days, without rescue therapy. About three times as many patients on the approved dose of 30 mg/kg every four weeks met that endpoint by week 24 as on placebo, and the result was statistically significant, the company said.

Patients in that group had a mean hemoglobin increase of 1 g/dL at week 1. On the FACIT-Fatigue scale, a key secondary endpoint, the mean improvement was 3.51 points greater than with placebo at week 24, a result J&J described as descriptive under the trial's statistical plan. Full results were presented at the European Hematology Association meeting in June 2026.

"More patients treated with IMAAVY achieved a durable hemoglobin response compared with placebo — meaning their red blood cell levels went up and stayed up," said David Kuter, a physician at Massachusetts General Hospital, in the company's release. J&J disclosed that Kuter has served as a consultant to the company.

Safety and what comes next

Safety in ENERGY was consistent with the drug's known profile in myasthenia gravis, J&J said. The product information warns that Imaavy may increase the risk of infections, including serious infections, and that severe allergic reactions, including angioedema and anaphylaxis, have occurred.

The company estimates that one to three people per 100,000 develop wAIHA each year and that about one in 8,000 people are living with it. J&J said it is investigating nipocalimab in rheumatologic diseases, rare autoantibody diseases and maternal-fetal diseases driven by maternal antibodies.