Emapalumab as a therapeutic intervention for Epstein–Barr virus-associated hemophagocytic lymphohistiocytosis: A case series

Rationale: Epstein–Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is characterized by a severe cytokine storm, heightened inflammatory response, and immune-mediated damage to tissues and organs. Standard treatment protocols for hemophagocytic lymphohistiocytosis often fall short in effectively controlling EBV-HLH, leading to a need for novel therapeutic options. Emapalumab, a monoclonal antibody targeting interferon-gamma, has shown promise due to its targeted cytokine modulation capabilities and favorable safety profile. This study aimed to evaluate the efficacy and safety of emapalumab in pediatric patients with EBV-HLH. Patient concerns: The case series involved 4 pediatric patients diagnosed with EBV-HLH who did not achieve disease control despite receiving comprehensive treatment. Diagnoses: All 4 pediatric patients were diagnosed with EBV-HLH. Interventions: Emapalumab was introduced as an adjunctive therapeutic intervention alongside the HLH-94 or L-DEP regimens for these patients. Outcomes: Among the 4 patients, 1 experienced severe multiorgan dysfunction and opted to discontinue therapy. The remaining 3 patients showed controlled disease progression with significant clinical improvements following emapalumab administration. These improvements included reduced levels of inflammatory markers, normalization of blood counts and liver function, and decreased Epstein–Barr virus viral load. Lessons: The findings suggest that emapalumab may be an effective and safe treatment option for pediatric EBV-HLH. However, further research is necessary to confirm these outcomes, especially in critically ill patients.