FDA Approves Gamifant® as First Treatment for Macrophage Activation Syndrome in Still’s DiseaseFDA Approves Gamifant® as First Treatment for Macrophage Activation Syndrome in Still’s Disease
Monday, June 30, 2025
Sobi® has received approval from the U.S. Food and Drug Administration (FDA) for its medicine Gamifant® (emapalumab-lzsg) to treat both adults and children, including newborns, with hemophagocytic lymphohistiocytosis (HLH)/macrophage activation syndrome (MAS) in cases of known or suspected Still’s disease. This includes systemic juvenile idiopathic arthritis (sJIA), where patients have not responded well to glucocorticoids, cannot tolerate them, or have repeated MAS episodes.
This marks the first time the FDA has approved a treatment specifically for MAS in Still’s disease, a severe and potentially life-threatening condition that involves extreme inflammation and, in some cases, failure of multiple organs. It is most often seen in children and adults with sJIA or adult-onset Still’s disease.
The FDA’s decision was based on pooled results from two key clinical studies (Phase 3: NCT05001737 and NI-0501-06: NCT03311854). In these studies, 54% of patients (21 out of 39) showed a complete response by the eighth week of treatment, while 82% (32 out of 39) reached clinical remission of MAS symptoms. The safety profile remained consistent with earlier studies, with the most frequently reported side effects being viral infections—such as cytomegalovirus—and skin rashes.
MAS is a rare and dangerous form of HLH, often driven by high levels of interferon gamma (IFNγ), leading to symptoms such as persistent fever, high ferritin levels, low blood cell counts, bleeding disorders, and enlargement of the liver and spleen.
Gamifant, which blocks interferon gamma, is already approved by the FDA for treating patients with primary HLH who have disease that is resistant to, keeps returning with, or cannot be managed by standard HLH therapy. This latest approval extends its use to patients with HLH/MAS linked to Still’s disease.
Source: prnewswire.com
