FDA approves Gamifant for macrophage activation syndrome in Still’s disease
Ella Day | June 30, 2025 | News story | Medical Communications, Research and Development | FDA, Immunology, Still's disease, gamifant, hemophagocytic lymphohistiocytosis, sobi
The US Food and Drug Administration (FDA) has approved Gamifant (emapalumab-lzsg) for the treatment of macrophage activation syndrome (MAS) in adult and paediatric patients with known or suspected Still’s disease, including systemic juvenile idiopathic arthritis. Announced by biopharma company Sobi, the approval makes Gamifant the first-ever FDA-approved therapy for MAS.
The decision is based on pooled data from two clinical studies, EMERALD and NI-0501-06, which showed that 54% of patients achieved complete response at week eight. Additionally, 82% of patients reached clinical MAS remission. The safety profile was consistent with previous studies, with the most common adverse effects being viral infections and rashes.
MAS is a severe, life-threatening complication of Still’s disease, marked by uncontrolled immune activation and hyperinflammation. It is considered a secondary form of haemophagocytic lymphohistiocytosis (HLH), with symptoms including persistent high fever, cytopenias, liver dysfunction and multi-organ failure.
“MAS in Still’s disease presents a significant unmet need. With Gamifant now FDA-approved, we have a targeted treatment option to help control hyperinflammation and reduce dependence on high-dose steroids,” said Alexei Grom, Cincinnati Children’s Hospital, Cinicinnati, US.
Gamifant is a monoclonal antibody that targets and neutralises interferon gamma, a key driver of hyperinflammation in HLH and MAS. The treatment is already approved in the US for primary HLH.
Ella Day
30/6/25
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