[{"id":"emerald-ep1","name":"Complete response at Week 8","type":"PRIMARY","unit":"%","results":[{"arm":"emerald-ema","label":"54% (21/39) CR at Week 8","value":54}],"timepoint":"Week 8","description":"MAS (macrophage activation syndrome) in Still's disease is a life-threatening complication where the immune system attacks the body's own organs. Complete response means all MAS markers normalized."}]

6 serious adverse drug reactions in 4 patients. 14 infusion-related reactions in 8 patients (none serious, none led to discontinuation). No new safety concerns beyond known HLH label.

EMERALD + NI-0501-06 pooled analysis supported FDA approval June 2025. 82% clinical remission rate is impressive. Market is meaningfully larger than primary HLH. Steroid-sparing effect (44% to <=0.5 mg/kg/day) is clinically important. This was a major label expansion for Gamifant.

MAS in Still's disease is driven by IFN-gamma overproduction. Same mechanism as primary HLH but in the context of an autoimmune/autoinflammatory disease. MAS affects ~15-25% of Still's patients (~44,000-60,000 patients in US), making this a significantly larger market than primary HLH (~1:100,000 births).