IMAAVY Shows Strong Results in Rare Blood Disorder Trial

Johnson & Johnson has reported positive results from the Phase 2/3 ENERGY study evaluating IMAAVY® (nipocalimab-aahu) in patients with warm autoimmune hemolytic anemia (wAIHA), a rare and potentially life-threatening autoimmune blood disorder that currently has no U.S. Food and Drug Administration (FDA)-approved treatments.

The company announced that the study met its primary endpoint, demonstrating that IMAAVY produced a statistically significant and durable improvement in hemoglobin levels compared with placebo. The findings, which are being presented at the 2026 European Hematology Association (EHA) Congress, represent a significant development for patients living with the chronic condition, which is characterized by the immune system mistakenly attacking and destroying red blood cells.

According to the study results, patients receiving the 30 mg/kg dose of IMAAVY experienced rapid and sustained improvements in anemia. Researchers reported that approximately three times as many patients achieved durable hemoglobin responses by Week 24 compared with those receiving placebo. In addition, patients treated with IMAAVY demonstrated an average increase in hemoglobin levels of at least 1 gram per deciliter as early as the first week of treatment, highlighting the therapy’s rapid onset of action.

Warm autoimmune hemolytic anemia is a rare disorder in which immunoglobulin G (IgG) autoantibodies target red blood cells, leading to their premature destruction. The condition can cause severe fatigue, shortness of breath, weakness, dizziness, and other debilitating symptoms. Current treatment approaches often rely on corticosteroids and broad immunosuppressive therapies, which are not specifically approved for the disease and may be associated with significant side effects.

The ENERGY study evaluated a stringent definition of durable hemoglobin improvement. Patients were required to achieve an increase of at least 2 g/dL from baseline, maintain hemoglobin levels of at least 10 g/dL, and sustain these improvements across multiple visits without requiring rescue therapies or modifications to background treatments.

Results showed that nearly two-thirds of patients treated with the 30 mg/kg dose achieved both a clinically meaningful increase in hemoglobin and maintained levels above 10 g/dL by Week 24. Researchers also observed improvements in fatigue, one of the most burdensome symptoms associated with the disease. Patient-reported reductions in fatigue emerged as early as Week 2 and were maintained throughout the 24-week treatment period.

Another notable finding from the study was a reduction in steroid use among patients receiving IMAAVY, addressing a key goal in the management of autoimmune diseases where long-term corticosteroid exposure can lead to serious complications.

Bruno Fattizzo, Assistant Professor at the Department of Oncology and Hematology-Oncology at the University of Milan, said the rapid and durable improvements in anemia observed in the trial are particularly important in clinical practice because they may help alleviate the severe fatigue commonly experienced by patients with wAIHA.

IMAAVY also demonstrated a safety profile consistent with previous studies and its approved use in generalized myasthenia gravis. The most frequently reported adverse events among patients receiving the therapy included peripheral edema, diarrhea, and fever. No new safety concerns were identified during the trial.

Johnson & Johnson highlighted that IMAAVY employs an immunoselective mechanism of action designed to target the pathogenic IgG autoantibodies responsible for red blood cell destruction while preserving other important immune functions. This approach distinguishes the therapy from broader immunosuppressive treatments commonly used in current practice.

Leonard L. Dragone, M.D., Ph.D., Disease Area Leader for Autoantibody and Rheumatology at Johnson & Johnson, described the findings as a major milestone, noting that the study represents the first large placebo-controlled trial of its kind in wAIHA. He emphasized that the therapy delivered durable hemoglobin improvements without introducing new safety signals in a disease area where approved treatment options remain absent.

The positive ENERGY trial results position IMAAVY as a promising potential treatment for warm autoimmune hemolytic anemia and may pave the way for future regulatory discussions aimed at bringing a targeted therapy to patients living with this rare blood disorder.