Compassionate Use of Emapalumab in Children with Life-Threatening Disorders: Real-World Data

Introduction: Life threatening hyperinflammation occurs in hemophagocytic lymphohistiocytosis (HLH) and during acute rejection of hematopoietic stem cell (HSC) grafts. Both conditions reflect acute activation of the immune system, in part due to overproduction of proinflammatory cytokines, particularly interferon gamma (IFNγ). Emapalumab, a fully human monoclonal antibody that binds to IFNγ, is approved by the FDA for refractory or recurrent primary HLH (pHLH) or in patients intolerant to conventional therapy. Off-label use of emapalumab has been reported for treatment of secondary HLH (sHLH) and for HSC graft rejection. The European Medicines Agency did not approve emapalumab for the treatment of HLH and many other regulatory authorities, including the Israeli Ministry of Health, have yet to approve emapalumab for clinical use. Pending such regulatory approval, emapalumab is available in Israel exclusively though the Managed Access Request Program (MAP) on a compassionate basis sponsored by Sobi (Swedish Orphan Biovitrum AB,Reg. no. 556038-9321). Experience that accumulates through on- and off-label use of emapalumab obtained via MAP enriches the knowledge base regarding the uses of this drug in the real-world clinical setting.