Sobi Receives Approval for Gamifant® as Treatment for Macrophage Activation Syndrome in Still’s Disease
Monday, June 30, 2025
Sobi® has announced that the US Food and Drug Administration (FDA) has approved Gamifant® (emapalumab-lzsg) as the first treatment for adults and children, including newborns, with macrophage activation syndrome (MAS) associated with Still’s disease.
MAS is a severe, potentially life-threatening complication seen in Still’s disease and other rheumatic conditions. It is a secondary form of haemophagocytic lymphohistiocytosis (HLH) and is driven by excessive immune system activity, especially interferon gamma (IFNγ). Symptoms often include persistent fever, high ferritin levels, reduced blood cell counts, abnormal clotting, and liver or spleen enlargement.
MAS is a severe complication arising from auto-inflammatory conditions such as sJIA. It can lead to multi-organ failure if not managed promptly. Gamifant is currently the only approved anti-IFNγ monoclonal antibody and is indicated in the US for intravenous treatment of primary HLH and MAS in Still’s disease.
Gamifant is a monoclonal antibody that blocks IFNγ, helping to reduce hyperinflammation. It is administered through intravenous infusion and had already been approved in the US for treating primary HLH in patients unresponsive to conventional therapies.
This approval covers patients with systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still’s disease who show inadequate response or intolerance to glucocorticoids, or those with recurrent MAS.
The decision is based on pooled data from two key clinical studies—Phase 3 (NCT05001737) and NI-0501-06 (NCT03311854). Findings showed that 54 per cent of patients achieved a complete response at eight weeks, and 82 per cent reached clinical remission of MAS. The safety and tolerability profile remained consistent with earlier trials, with common side effects including viral infections and skin rashes.
This latest FDA approval expands its use to include MAS associated with Still’s disease, marking a significant milestone in the management of this rare condition and providing a new treatment option for patients with limited alternatives.
Source: sobi.com
