FDA Grants Priority Review to Sobi’s sBLA for Gamifant (emapalumab-lzsg)

Sobi announced that the U.S. Food and Drug Administration (FDA) has accepted the supplemental Biologics License Application (sBLA) for Gamifant (emapalumab-Izsg) for use in adult and paediatric patients with hemophagocytic lymphohistiocytosis (HLH)/macrophage activation syndrome (MAS) in Still’s disease with an inadequate response or intolerance to glucocorticoids, or with recurrent MAS. The application was granted Priority Review with a PDUFA date of June 27, 2025.

HLH/MAS, a form of HLH, is a severe complication of rheumatic diseases, occurring most frequently in Still’s disease including systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still’s disease (AOSD). HLH/MAS is a rare systemic disorder of hyperinflammation with common clinical manifestations such as high persistent fever, elevated ferritin, cytopenias, coagulopathies, and hepatosplenomegaly.

“HLH/MAS in Still’s disease is a serious and potentially fatal complication where patients can experience intense hyperinflammation and even multiple organ failure,” said Lydia Abad-Franch, MD, MBA, Head of R&D and Chief Medical Officer at Sobi. “There is no approved therapy for HLH/MAS today. Gamifant (emapalumab-Izsg) selectively neutralizes interferon gamma (IFN-γ), a key driver of hyperinflammation, and if approved, may also help reduce the need for high-dose glucocorticoids in these patients.”

The application is based on results from pooled data from two studies which enrolled a total of 39 patients, the EMERALD (NCT05001737) and the NI-0501-06 (NCT03311854) studies. Fifty-three percent of patients had a complete response at Week 8 and 85% had a complete response at any time during the studies. Weekly mean glucocorticoid doses were reduced by 70.1% after 2 weeks of treatment.

Gamifant (emapalumab-Izsg) a monoclonal antibody that binds and neutralises interferon gamma (IFN-y), was approved by the FDA in 2018 for the treatment of adult and paediatric (newborn and older) patients with primary HLH with refractory, recurrent, or progressive disease or intolerance with conventional HLH therapy.