Emapalumab, sold under the brand name Gamifant, is an anti- interferon-gamma (IFNγ) antibody medication used for the treatment of

hemophagocytic lymphohistiocytosis In hematology, hemophagocytic lymphohistiocytosis (HLH), also known as haemophagocytic lymphohistiocytosis ( British spelling), and hemophagocytic or haemophagocytic syndrome, is an uncommon hematologic disorder seen more often in children than ...

(HLH), which has no cure. The most common side effects include infections, hypertension, infusion-related reactions, and pyrexia. The U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) considers it to be a

first-in-class medication A first-in-class medication is a prototype drug that uses a "new and unique mechanism of action" to treat a particular medical condition. While the Food and Drug Administration's Center for Drug Evaluation and Research tracks first-in-class medic ...

. In June 2025, the U.S.

(FDA) approved emapalumab-lzsg for the treatment of macrophage activation syndrome (MAS) in patients with Still’s disease.

Medical uses

Emapalumab is used to treat primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent or progressive disease or intolerance with conventional HLH therapy.

Adverse effects

In the clinical trials that lead to emapalumab's FDA approval, the most commonly reported adverse effects were infections (56%), high blood pressure (41%), infusion reactions (27%), and fever (24%). Serious adverse effects occurred in about half of the subjects studied in the clinical trial that led to its FDA approval.

Pharmacology

Mechanism of action

In the setting of HLH, over-secretion of IFN-γ is thought to contribute to the pathogenesis of the disease. Emapalumab binds and neutralizes IFN-γ, preventing it from inducing pathological effects.

Pharmacokinetics

Like other antibody-based medications, which are made of amino acid chains called

polypeptides Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty ami ...

, emapalumab is broken down into smaller peptides via the body's normal

catabolism Catabolism () is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. Catabolism breaks down large molecules (such as polysaccharides, lipid ...

Society and culture

Legal status

The U.S.

(FDA) granted

orphan drug An orphan drug is a medication, pharmaceutical agent that is developed to treat certain rare medical conditions. An orphan drug would not be profitable to produce without government assistance, due to the small population of patients affected by th ...

designations in 2010 and 2020, and

breakthrough therapy Breakthrough therapy is a United States Food and Drug Administration designation that expedites drug development that was created by Congress under Section 902 of the 9 July 2012 Food and Drug Administration Safety and Innovation Act. The FDA's "b ...

designation in 2016, on the basis of preliminary data from the phase II trial. In July 2020, and again in November 2020, the

European Medicines Agency The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of pharmaceutical products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products ...

(EMA) recommended the refusal of the marketing authorization for emapalumab. In June 2025, the FDA approved emapalumab-lzsg for the treatment of macrophage activation syndrome (MAS) in patients with Still’s disease.

Research

The research name of emapalumab was NI-0501. A phase II/III trial began in 2013 and is ongoing . The trial targets patients under the age of 18 who have failed to improve on conventional treatments. This study was realised in the context of an EU-funded FP7 project, named FIGHT-HLH (306124).

References

External links

* {{Authority control Experimental monoclonal antibodies Orphan drugs