Emapalumab in Children with Primary Hemophagocytic Lymphohistiocytosis
Franco Locatelli1, Michael B Jordan1, Carl Allen1
1From the Department of Pediatrics, Sapienza, University of Rome (F.L.), and the Department of Pediatric Hematology-Oncology (F.L.) and Division of Rheumatology (F.D.B.), IRCCS Bambino Gesù Children's Hospital, Rome, Pediatric Hematology-Oncology, Woman and Child Hospital, Azienda Ospedaliera Universitaria Integrata, Verona (S.C.), the Pediatric Hematology-Oncology Unit, Department of Pediatrics, University of Milano-Bicocca, Monza Brianza per il Bambino e la sua Mamma Foundation, Monza (C.R.), the Clinic of Pediatric Hematology-Oncology, University Hospital of Padova, Padua (M.-C.P.), and the Division of Pediatric Onco-Hematology, Regina Margherita Hospital, Turin (F.F.) - all in Italy; the Divisions of Immunobiology and Bone Marrow Transplantation and Immune Deficiency, Department of Pediatrics (M.B.J.), and the Division of Rheumatology (A.G.), Cincinnati Children's Hospital Medical Center, and the University of Cincinnati College of Medicine (M.B.J.) - all in Cincinnati; the Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston (C.A.); the Department of Hematology, Great Ormond Street Hospital for Children, London (A.R.); the Department of Pediatric Hematology-Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston (B.D.); the Center for Cancer and Blood Disorders, Children's Hospital Colorado, Aurora (T.P.G.); the Departments of Pediatric Hematology-Oncology and Hematology and Oncology, Fundación para la Investigación Biomédica Hospital Infantil Universitario Niño Jesús, Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid (J.S.), and the Department of Pediatric Hematology and Oncology, Hospital Universitari Vall d'Hebron, Barcelona (J.-L.D.D.); the Department of Pediatric Hematology and Oncology, University Children's Hospital, Muenster, Germany (M.A.); the Center for Cancer and Blood Disorders, Phoenix Children's Hospital, Phoenix, AZ (M.H.); NovImmune, Plan-les-Ouates, Switzerland (G.L., M.B., C.M.); and MnS Modelling and Simulation, Dinant, Belgium (P.J.).
Background:
Primary hemophagocytic lymphohistiocytosis is a rare syndrome characterized by immune dysregulation and hyperinflammation. It typically manifests in infancy and is associated with high mortality.
Methods:
We investigated the efficacy and safety of emapalumab (a human anti-interferon-γ antibody), administered with dexamethasone, in an open-label, single-group, phase 2-3 study involving patients who had received conventional therapy before enrollment (previously treated patients) and previously untreated patients who were 18 years of age or younger and had primary hemophagocytic lymphohistiocytosis. The patients could enter a long-term follow-up study until 1 year after allogeneic hematopoietic stem-cell transplantation or until 1 year after the last dose of emapalumab, if transplantation was not performed. The planned 8-week treatment period could be shortened or extended if needed according to the timing of transplantation. The primary efficacy end point was the overall response, which was assessed in the previously treated patients according to objective clinical and laboratory criteria.
Results:
At the cutoff date of July 20, 2017, a total of 34 patients (27 previously treated patients and 7 previously untreated patients) had received emapalumab; 26 patients completed the study. A total of 63% of the previously treated patients and 65% of the patients who received an emapalumab infusion had a response; these percentages were significantly higher than the prespecified null hypothesis of 40% (P = 0.02 and P = 0.005, respectively). In the previously treated group, 70% of the patients were able to proceed to transplantation, as were 65% of the patients who received emapalumab. At the last observation, 74% of the previously treated patients and 71% of the patients who received emapalumab were alive. Emapalumab was not associated with any organ toxicity. Severe infections developed in 10 patients during emapalumab treatment. Emapalumab was discontinued in 1 patient because of disseminated histoplasmosis.
Conclusions:
Emapalumab was an efficacious targeted therapy for patients with primary hemophagocytic lymphohistiocytosis. (Funded by NovImmune and the European Commission; NI-0501-04 and NI-0501-05 ClinicalTrials.gov numbers, NCT01818492 and NCT02069899.).
