FDA Approves First Drug for Warm Autoimmune Hemolytic Anemia

The U.S. Food and Drug Administration (FDA) has approved Imaavy (nipocalimab-aahu) injection for warm autoimmune hemolytic anemia (wAIHA) in adult and pediatric patients 12 years of age and older currently or previously treated with corticosteroids.

Condition

wAIHA is a rare blood disorder where the immune system mistakenly attacks and destroys the body’s own red blood cells — a process called hemolysis. This destruction happens faster than the body can replace the red blood cells, leading to a shortage of healthy red blood cells (anemia).

Normally, red blood cells live about 120 days and deliver oxygen throughout the body. In wAIHA, a type of antibody called immunoglobulin G (IgG) mistakenly tags red blood cells for destruction by immune cells. The disease is called "warm" because this process occurs at normal body temperature.

wAIHA is the most common type of autoimmune hemolytic anemia, affecting approximately 1 to 3 per 100,000 people per year and can occur at any age. Imaavy is the first FDA-approved treatment for this serious condition.

Data Supporting Imaavy

FDA based its approval on results from the wAIHA Study (NCT04119050), a 24-week, randomized, double-blind, placebo-controlled clinical trial. The study enrolled patients with a confirmed wAIHA diagnosis of at least 3 months who had low hemoglobin levels (below 10 g/dL), evidence of active red blood cell destruction (hemolysis), and a positive direct antiglobulin test (DAT) - a blood test that detects antibodies attacking red blood cells. All patients had previously received or were currently receiving treatment for wAIHA, reflecting a population with a significant unmet medical need.

In this study, 118 patients were randomly assigned to one of three treatment groups: Imaavy 30 mg/kg given by IV infusion once every 4 weeks; Imaavy 15 mg/kg given by IV infusion once every 2 weeks; or placebo (an inactive treatment). Patients were allowed to remain on stable doses of other medications they had been taking for wAIHA.

A key measure of effectiveness was whether patients achieved a durable hemoglobin response — a meaningful and sustained improvement in red blood cell levels.

The proportion of patients with a durable hemoglobin response was 24% in the Imaavy 30 mg/kg arm compared to 8% in the placebo arm. The 15 mg/kg arm did not lead to a higher proportion of patients with a durable hemoglobin response compared to placebo.

Safety Information

The most common adverse reactions in patients with wAIHA treated with Imaavy were peripheral edema (swelling of the lower legs, ankles, feet caused by a build-up of fluid in body tissues), fatigue, diarrhea and fever.

Other side effects are infusion-related reactions, including headache, influenza-like illness, rash, nausea, dizziness, chills, and erythema (redness of the skin).

Designation

FDA granted Imaavy Fast Track, priority review, and orphan designations for this indication. Approval was granted to Janssen Biotech, Inc.