New data for emapalumab in the treatment of macrophage activation syndrome to be presented at the ACR conference

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STOCKHOLM, Oct. 30, 2024 /PRNewswire/ -- Sobi® (STO: SOBI) today announced that new research showing the effect of emapalumab in patients with macrophage activation syndrome (MAS) in Still's disease, including systemic juvenile idiopathic arthritis (sJIA) and adult-onset still's disease (AOSD) who had an inadequate response to high-dose glucocorticoids (GCs) will be presented at the American College of Rheumatology (ACR) Convergence in Washington D.C. The data were pooled from two open-label, single-arm interventional studies, the phase 3 NI-0501-14 study [EMERALD; NCT05001737] and NI-0501-06 [NCT03311854], including 39 patients with MAS. 

Key results:

  • Complete response at week 8: At week 8, 21 patients (53.8%) achieved a complete response (95% confidence interval (CI): 37.2–69.9%).

  • Complete response at any time: 33 patients (85%) achieved a complete response at any time during the studies.

  • Glucocorticoid tapering: Weekly mean glucocorticoid doses were reduced by 70.1% after 2 weeks of treatment. By week 8, glucocorticoids were tapered to a clinically meaningful dose of ≤1 mg/kg/day in 28 patients (72%) and to ≤0.5 mg/kg/day in 17 patients (44%).

  • Safety: No new safety concerns were identified during the studies.

"MAS in Still's disease is a severe condition characterised by intense hyperinflammation and multiple organ failure. Those affected, including young children, often experience high fevers, liver and spleen enlargement, severe cytopenias, and neurological symptoms," said Lydia Abad-Franch, MD, Head of Research & Development and Medical Affairs and Chief Medical Officer at Sobi. "The results to be presented at ACR indicate that emapalumab could potentially provide a new therapeutic option, offering effective control of MAS symptoms and possibly reducing the need for high-dose glucocorticoids. This represents an important development in the treatment landscape for MAS."

Additional key results:

  • Overall response (OR) by week 8: 32 patients (82.4%) achieved an overall response by week 8. OR was observed as early as day 5, with a median time to first OR of 2.3 weeks.

  • Clinical MAS remission: 32 patients (82.1%) achieved investigator-assessed clinical MAS remission at any time , with a median time to clinical remission of 3.3 weeks.

  • Survival rate: 37 patients (94.9%) were alive at week 8.

Emapalumab is a monoclonal antibody that neutralises interferon gamma (IFNγ), a key cytokine which contributes to the inflammation and tissue damage seen in MAS. The purpose of these two prospective studies is to assess the efficacy and safety of emapalumab in controlling MAS in patients with Still's disease, including sJIA and AOSD, who had an inadequate response to high-dose glucocorticoids. In May 2024, the US FDA granted emapalumab fast track designation as a potential therapeutic option in patient with MAS. Sobi plans to submit an sBLA for this indication to the FDA in 2024.