Photo Credit: Artur Plawgo
Macrophage activation syndrome (MAS) is a life-threatening complication of Still’s disease. In two prospective open-label studies, NI-0501-06 and EMERALD, emapalumab rapidly controlled MAS when it occurred in greater than 80% of patients and allowed clinically meaningful reductions in glucocorticoid dosing in 72% of those with an initial inadequate response to high-dose glucocorticoid treatment.
MAS is characterized by interferon-gamma (IFNγ)-driven macrophage activation and systemic hyperinflammation. Emapalumab provides rapid and targeted neutralization of IFNg. Alexei Grom, MD, from Cincinnati Children’s Hospital, in Ohio, presented data from two pooled prospective, open-label studies, the phase 2 NI-0501-06 trial (NCT03311854) and the phase 3 EMERALD trial (NCT05001737), in Still’s disease patients with MAS not sufficiently resolved with high-dose glucocorticoids1. There were 39 participants, with a mean age of 12 years and 80% women, received 4 weeks of emapalumab treatment. The primary efficacy endpoint was complete response (CR) after 8 weeks. CR had 8 components, all of which had to be met: absence of clinical signs and symptoms of MAS and seven laboratory parameters relevant to MAS.
After 8 weeks, 21 (53.8%) participants achieved CR, and 33 (85%) achieved CR at any time. Excluding lactate dehydrogenase from the endpoint, the CR rate at week 8 increased to 69.2%. By week 8, 32 (82.4%) participants had at least a partial response. Dr. Grom added that 32 (82.1%) participants achieved investigator-assessed clinical MAS remission after a median of 3.3 weeks. Two participants had died after 8 weeks.
The high and quick response rate allowed for significant glucocorticoid dose tapering. At baseline, the mean dose was 9.7 mg/kg/day, which decreased to 2.9 mg/kg/day at week 2 and 0.8 mg/kg/day at week 8. There were no new safety issues concerning emapalumab. There were six serious adverse drug reactions in four participants and 14 non-serious infusion-related reactions in eight participants.
Medical writing support was provided by Michiel Tent
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