Sobi has received the US Food and Drug Administration (FDA) approval for Gamifant (emapalumab-lzsg) to treat macrophage activation syndrome (MAS) in Still’s disease.
Gamifant, a monoclonal antibody that targets and neutralises interferon gamma (IFNγ), addressing hyperinflammation, is administered via intravenous infusion over one hour.
The drug is already approved in the US for primary hemophagocytic lymphohistiocytosis (HLH) in patients with refractory, recurrent, or progressive disease or intolerance to conventional therapy.
The current approval extends its use in people with MAS in Still’s disease, including systemic juvenile idiopathic arthritis (sJIA).
It applies to both adult and paediatric patients who have shown an inadequate response or intolerance to glucocorticoids or have recurrent MAS.
Sobi CEO Guido Oelkers said: “With our expertise in primary hemophagocytic lymphohistiocytosis, we understand the urgency of managing MAS quickly to improve patient outcomes.
“Gamifant is already an established therapy making a meaningful difference for patients with primary HLH, and with this approval, we are excited about the opportunity to positively impact patients affected by MAS in Still’s Disease.”
MAS is a severe complication of rheumatic diseases, particularly in Still’s disease, characterised by fever, hepatosplenomegaly, liver dysfunction, cytopenias, and coagulation abnormalities.
It is a secondary form of HLH, a rare systemic disorder driven by IFNγ-induced hyperinflammation, and can progress to multiple organ failure and death, if untreated.
The FDA approval was based on pooled data from two studies, including a Phase 3 trial.
The study results showed that 54% of patients achieved a complete response by Week 8, and 82% reached clinical MAS remission.
The safety profile of Gamifant was consistent with previous studies, with common adverse events including viral infections and rash.
Cincinnati Children’s Hospital Medical Center Research Director Division of Rheumatology, professor of Pediatrics Alexei Grom said: “MAS in Still’s disease is a serious and potentially life-threatening complication, marked by severe hyperinflammation and, in some cases, multi-organ failure.
“Many patients affected by MAS—both young children and adults, face significant unmet medical needs.
“With Gamifant now as the first FDA-approved treatment for MAS, we have a new therapeutic option that helps control hyperinflammation and reduce our reliance on high-dose glucocorticoids.”
