152 - Real-World Demographics, Clinical Characteristics, and Treatment Patterns of Patients Treated With Emapalumab for Hemophagocytic Lymphohistiocytosis (HLH) and Non-HLH Conditions in the US (REAL-HLH

Poster Number: 152
Publication Number: 152.22

Carl E. Allen, Baylor College of Medicine, Houston, TX, United States; Shanmuganathan Chandrakasan, Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA, United States; michael jordan, CINCINNATI CHILDREN'S HOSP MED CTR, CINCINNATI, OH, United States; Jennifer W. Leiding, Johns Hopkins University School of Medicine, St. Petersburg, FL, United States; Abiola Oladapo, Sobi Inc, Concord/USA, MA, United States; Priti Pednekar, PRECISIONheor, Boston, MA, United States; Kelly Walkovich, University of Michigan Medical School, Ann Arbor, MI, United States; John D.. Yee, Sobi Inc., Waltham, MA, United States

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening, hyperinflammatory syndrome caused by overproduction of proinflammatory cytokines, particularly interferon gamma (IFNγ). Real-world evidence is lacking on emapalumab, an anti-IFNγ monoclonal antibody approved for patients with primary HLH (pHLH) with refractory, recurrent, or progressive disease, or intolerance to conventional HLH therapy by the US Food and Drug Administration in November 2018.

Objective: To assess real-world treatment patterns and outcomes, and clinical and demographic characteristics in patients with HLH and non-HLH conditions treated with emapalumab in the United States.

Design/Methods: A retrospective medical chart review conducted across 33 US hospitals identified patients treated with ≥1 dose of emapalumab between November 20, 2018, and October 31, 2021. Data were extracted from time of emapalumab initiation to end of data availability, death, or study end (December 31, 2021).

Results: More than half of the study patients (N=105; mean age [± SD], 9.2 [8.5] years) were male (56.2%) and non-White (55.2%). Mean age (±SD) at HLH diagnosis for patients with physician-reported diagnosis of pHLH (n=41) and secondary HLH (sHLH, n=57) was 4.7 (7.9) and 9.3 (7.5) years, respectively. In pHLH and sHLH (n=98), the most common reasons for initiating emapalumab were treatment of refractory (39.8%), progressive (23.5%), and recurrent (22.4%) disease. All patients in the non-HLH group (n=7) received emapalumab to prevent hematopoietic stem-cell transplantation (HSCT) graft rejection or failure. Median (range) time to emapalumab initiation from HLH diagnosis was 30 (2-759) and 16.5 (1-2278) days among patients with pHLH and sHLH, respectively. Median (range) treatment duration with emapalumab was 66.0 (1-523) and 38.0 (1-397) days among patients with pHLH and sHLH, respectively. Median (range) emapalumab starting and cumulative treatment doses were 1.4 (0.8-9.8) and 66.8 (1.0-512.2) mg/kg in pHLH; 1.1 (0.7-5.9) and 21.3 (1-336.5) mg/kg in sHLH; and 8.7 (0.7-10.3) and 10.3 (3.9-40.0) mg/kg in non-HLH. Median (range) maximum administered single emapalumab dose was 3.8 (0.8-11.2) mg/kg in pHLH; 2.3 (0.7-12.5) mg/kg in sHLH; and 8.7 (0.7-10.3) mg/kg in non-HLH.

Conclusion(s):

This is the first study describing real-world treatment patterns with emapalumab across a diverse patient population with HLH and non-HLH conditions.