The FDA has approved J&J’s IMAAVY® (nipocalimab-aahu) as the first targeted treatment for warm autoimmune hemolytic anemia (wAIHA) in adults and teens 12+
Written by: Kirti Kumbhar, M. Pharm (QA)
Reviewed by: Pharmacally Editorial Team
On August 24, 2026, Johnson & Johnson announced that the U.S. Food and Drug Administration (FDA) approved IMAAVY® (nipocalimab-aahu) for the treatment of warm autoimmune hemolytic anemia (wAIHA) in adults and pediatric patients 12 years of age and older who are currently or previously treated with corticosteroids. The approval marks the first FDA-approved treatment specifically for wAIHA, a rare and potentially life-threatening autoimmune disease.
In wAIHA, pathogenic immunoglobulin G (IgG) autoantibodies attach to and destroy red blood cells, resulting in anemia and profound fatigue. The condition affects approximately 1–3 people per 100,000 annually, with about 1 in 8,000 individuals living with wAIHA. Patients are also at increased risk of complications including venous thrombotic events, acute renal failure, and infection. Before this approval, treatment options included corticosteroids and immunosuppressants, which broadly suppress immune activity rather than specifically targeting the pathogenic IgG autoantibodies.
Targeting the FcRn Pathway
IMAAVY is an immunoselective treatment designed to bind with high affinity to and block the neonatal Fc receptor (FcRn). By blocking FcRn, IMAAVY reduces circulating IgG antibodies that drive disease while preserving B-cell function, based on in vitro and/or in vivo studies.
The approval adds to IMAAVY’s previous U.S. approval for generalized myasthenia gravis (gMG). In April 2025, IMAAVY was approved for adults and pediatric patients 12 years of age and older with anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody-positive gMG.
ENERGY Study Supports Approval
The approval was based on the pivotal Phase 2/3 ENERGY study (NCT04119050), a multicenter, randomized, double-blind, placebo-controlled trial evaluating nipocalimab in adults with wAIHA. A total of 115 adults were randomized approximately 1:1:1 to receive nipocalimab at two dose schedules or placebo. The double-blind treatment period lasted 24 weeks, after which patients could enter a 144-week open-label extension.
The primary endpoint was durable hemoglobin (Hgb) response, defined as a hemoglobin concentration of ≥10 g/dL and an increase from baseline of ≥2 g/dL for at least 28 days, with the criteria met starting by Week 16 and without rescue therapy. Approximately three times as many patients receiving the approved dose achieved a durable Hgb response compared with placebo by Week 24, with statistical significance. The approved regimen is IMAAVY 30 mg/kg administered intravenously every four weeks.
Hemoglobin Response and Fatigue Improvements
IMAAVY produced an early improvement in hemoglobin, with a mean increase of 1 g/dL at Week 1. Among responders, the median time to first Hgb response was 4.1 weeks with IMAAVY 30 mg/kg every four weeks compared with 12.1 weeks with placebo. These results were considered descriptive according to the study’s pre-specified statistical analysis plan.
At Week 24, the mean FACIT-Fatigue score was 3.51 points higher with IMAAVY than with placebo (95% CI, 0.64–6.39), with higher scores indicating less fatigue. This analysis was also considered descriptive.
Safety Profile and Ongoing Development
The safety profile of IMAAVY in ENERGY was consistent with its established safety profile in gMG. The most common adverse reactions in patients with wAIHA were peripheral edema, diarrhea, and fever.
The full ENERGY study results were presented at the European Hematology Association 2026 Congress in June 2026.
Johnson & Johnson is continuing to investigate nipocalimab across rheumatologic diseases, rare autoantibody diseases, and maternal-fetal diseases mediated by maternal alloantibodies. For wAIHA, nipocalimab previously received FDA Fast Track designation in July 2019, Orphan Drug status in December 2019, and Priority Review in 2026. The legal manufacturer of IMAAVY is Janssen Biotech, Inc.
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About the Writer
Kirti Kumbhar (LinkedIn) is an M.Pharm graduate with experience in Quality Assurance at Lupin Limited and a strong interest in clinical research, regulatory affairs, and Trial Master File (TMF) management. She has developed knowledge of regulatory documentation, quality systems, compliance, and healthcare research through her professional experience. Passionate about clinical development and continuous learning, Kirti is committed to supporting high-quality healthcare documentation, regulatory excellence, and research-driven healthcare advancements.