FDA's Priority Review Boosts Sobi's Gamifant for HLH/MAS in Still's Disease

The U.S. Food and Drug Administration (FDA) has granted Priority Review to Sobi's supplemental Biologics License Application (sBLA) for Gamifant® (emapalumab-lzsg), a potential game-changer in the treatment of hemophagocytic lymphohistiocytosis (HLH)/macrophage activation syndrome (MAS) in Still's disease. This is a significant milestone for Sobi, as it brings the company one step closer to providing a much-needed treatment option for patients suffering from this severe and potentially fatal complication.



HLH/MAS is a rare systemic disorder characterized by hyperinflammation, with common clinical manifestations such as high persistent fever, elevated ferritin, cytopenias, coagulopathies, and hepatosplenomegaly. It is a serious and potentially fatal complication of rheumatic diseases, occurring most frequently in Still's disease, including systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD). Currently, there is no approved therapy for HLH/MAS, making Gamifant® a promising candidate to address this unmet medical need.

The FDA's Priority Review status for Sobi's sBLA for Gamifant® is based on results from pooled data from two studies, EMERALD (NCT05001737) and NI-0501-06 (NCT03311854), which enrolled a total of 39 patients. The key clinical trial results that support the FDA's decision include:

1. Efficacy: Fifty-three percent of patients had a complete response at Week 8, and 85% had a complete response at any time during the studies. This indicates that Gamifant® was effective in treating HLH/MAS in Still's disease.
2. Reduction in glucocorticoid doses: Weekly mean glucocorticoid doses were reduced by 70.1% after 2 weeks of treatment. This suggests that Gamifant® may help reduce the need for high-dose glucocorticoids in these patients.
3. Safety: The most common adverse reactions reported during the studies were infections (56%), hypertension (41%), infusion-related reactions (27%), and fever (24%). These adverse reactions are manageable and comparable to those seen with existing treatments for HLH/MAS in Still's disease.

Gamifant® is an anti-interferon gamma (IFN-γ) monoclonal antibody that binds to and neutralises IFN-γ. In the USA, Gamifant® is the first and only treatment approved by the FDA 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. The FDA approval is based on data from the phase 2/3 studies (NCT01818492 and NCT02069899).

The approval of Gamifant® for HLH/MAS in Still's disease aligns with Sobi's strategic focus on addressing unmet medical needs and expanding its product pipeline. By gaining approval for Gamifant® in this indication, Sobi is addressing a significant unmet medical need and providing a much-needed treatment option for patients suffering from this condition. Additionally, the approval of Gamifant® for HLH/MAS in Still's disease expands Sobi's product pipeline, adding another indication to its portfolio of innovative medicines. This expansion allows Sobi to offer a broader range of treatments to patients and healthcare providers, further solidifying its position in the biopharmaceutical market.

In conclusion, the FDA's Priority Review status for Sobi's sBLA for Gamifant® is a significant milestone in the company's journey to bring transformative treatments to patients with high medical needs. With the potential approval of Gamifant® for HLH/MAS in Still's disease, Sobi is poised to make a substantial impact on the lives of patients suffering from this severe and potentially fatal complication.