Emapalumab for the treatment of relapsed/refractory hemophagocytic lymphohistiocytosis

Emapalumab is a fully human immunoglobulin G1 monoclonal antibody directed against interferon-γ (IFN-γ), which in November 2018 received the first global approval for the treatment of pediatric and adult patients with primary hemophagocytic lymphohistiocytosis (HLH) with refractory, recurrent, or progressive disease or intolerance to HLH therapy. This review will highlight the pathophysiology of primary HLH, the therapeutic rationale for use of IFN-γ-targeting therapy, and potential limitations to its broader use in the treatment of HLH.