FDA approves nipocalimab as first treatment for warm autoimmune hemolytic anemia

The FDA has approved nipocalimab-aahu (Imaavy, Johnson & Johnson) for warm autoimmune hemolytic anemia (wAIHA) in adults and adolescents 12 years and older who are currently or previously treated with corticosteroids, marking the first therapy specifically indicated for the disease.¹ The decision follows Priority Review and is based on results from the Phase 2/3 ENERGY trial.¹

"Living with wAIHA often means relentless fatigue and the constant uncertainty of not knowing what tomorrow will bring," said Karen Jones, president and executive director of wAIHA Warriors, a patient advocacy organization. "Patients may cycle through periods where they start to feel like themselves again — and then their hemoglobin drops, the exhaustion returns, and they're back to square one. For the first time, our community has a treatment specifically for our disease."¹

Nipocalimab trial design and efficacy in wAIHA

ENERGY (NCT04119050) was a multicenter, randomized, double-blind, placebo-controlled Phase 2/3 study of 115 adults with wAIHA, randomized roughly 1:1:1 to two nipocalimab dosing schedules or placebo, followed by an open-label extension.¹ The primary endpoint was durable hemoglobin response, defined as hemoglobin of at least 10 g/dL with a sustained increase from baseline of at least 2 g/dL for 28 days without rescue therapy.¹ At the approved dose of 30 mg/kg intravenously every 4 weeks, roughly three times as many nipocalimab-treated patients achieved durable response by week 24 versus placebo, a statistically significant difference.¹ Mean hemoglobin rose 1 g/dL by week 1, with median time to first response of 4.1 weeks versus 12.1 weeks for placebo.¹ Fatigue, measured by FACIT-Fatigue, improved by a mean of 3.5 points more than placebo at week 24.¹ The most common adverse reactions (≥10%) were peripheral edema, diarrhea, and fever, consistent with the drug's established gMG safety profile.¹

Disease burden and unmet need in warm autoimmune hemolytic anemia

wAIHA is a rare, life-threatening condition in which immunoglobulin G (IgG) autoantibodies bind to and destroy red blood cells, causing severe anemia and profound fatigue.¹ It affects an estimated 1 to 3 new patients per 100,000 annually, with roughly 1 in 8,000 individuals living with the condition, and incidence rises after age 50.³ Complications include venous thromboembolism, acute kidney injury, and infection.¹ Until now, management relied on corticosteroids and nonspecific immunosuppressants that dampen the entire immune system rather than the pathogenic autoantibodies driving hemolysis, leaving many patients with relapsing disease and treatment-related toxicity.²

Mechanism of action and regulatory history of nipocalimab

Nipocalimab is a monoclonal antibody that blocks the neonatal Fc receptor (FcRn), reducing circulating IgG — including pathogenic autoantibodies — while preserving broader immune and B-cell function.¹ It was first approved in April 2025 for gMG in patients 12 years and older who are anti-acetylcholine receptor or anti-muscle-specific tyrosine kinase antibody positive; this wAIHA approval is its second indication.¹ The drug also holds FDA Fast Track, Orphan Drug, and Breakthrough Therapy designations across several autoantibody-driven diseases, including hemolytic disease of the fetus and newborn and Sjögren disease.¹

Interpreting the ENERGY data

David Kuter, MD, DPhil, of Massachusetts General Hospital and Harvard Medical School, framed the results as evidence that targeting IgG directly can change the treatment paradigm for wAIHA rather than simply managing symptoms.¹

Limitations and what comes next

The ENERGY trial enrolled adults only; the pediatric indication (ages 12-17) rests on extrapolation and pharmacokinetic bridging rather than direct pediatric efficacy data, a common but important caveat for this age group. The open-label extension, running through 144 weeks, should clarify durability and long-term safety beyond the 24-week primary analysis. Cost, access, and the drug's infusion requirement every 4 weeks may also shape real-world uptake alongside corticosteroids and off-label agents such as rituximab.

References

1. Johnson & Johnson. FDA approves IMAAVY® (nipocalimab-aahu) as first-ever treatment for warm autoimmune hemolytic anemia (wAIHA), representing a landmark advancement for patients. August 24, 2026. Accessed August 25, 2026. https://www.jnj.com/media-center/press-releases/fda-approves-imaavy-nipocalimab-aahu-as-first-ever-treatment-for-warm-autoimmune-hemolytic-anemia-waiha-representing-a-landmark-advancement-for-patients

2. Sudulagunta SR, Sepehrar M, Sodalagunta MB, et al. Warm autoimmune hemolytic anemia: clinical profile and management. J Hematol. 2017;6(1):12-20. doi:10.14740/jh303w

3. National Organization for Rare Disorders. Warm autoimmune hemolytic anemia. Accessed August 25, 2026. https://rarediseases.org/rare-diseases/warm-autoimmune-hemolytic-anemia/

4. ClinicalTrials.gov. Study of nipocalimab in adults with warm autoimmune hemolytic anemia (ENERGY). Identifier NCT04119050. Accessed August 25, 2026. https://www.clinicaltrials.gov/study/NCT04119050