OP0253 REAL-WORLD DEMOGRAPHICS, CLINICAL CHARACTERISTICS, AND TREATMENT PATTERNS OF PATIENTS TREATED WITH EMAPALUMAB FOR SECONDARY HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSIS IN THE UNITED STATES: THE REAL-HLH STUDY

Background Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening, hyperinflammatory syndrome caused by overproduction of proinflammatory cytokines, e.g., interferon gamma (IFNγ).[1,2] Secondary HLH (sHLH) occurs in the context an underlying disease (e.g., rheumatologic, malignancy, or iatrogenic) and/or infectious trigger.[1,2] Emapalumab fully human anti-IFNγ monoclonal antibody that binds to and neutralizes biological activity IFNγ. It was approved FDA 2018 for adults children with primary refractory, recurrent, progressive disease, intolerance conventional therapy. Since its approval, real-world evidence on use emapalumab routine clinical setting limited.[3-5] The REAL-HLH study assessed treatment patterns among patients treated emapalumab. Objectives To describe demographics, characteristics, subset physician-reported diagnosis sHLH Methods A retrospective medical chart review conducted across 33 US hospitals identified ≥1 dose between November 20, 2018, October 31, 2021. Data extracted from time initiation end data availability, death, (December 2021) are presented. Results Overall, 57/105 (54.3%) enrolled had (mean age [± SD] 10.4 [7.6] years). Majority were non-White (63.2%) male (52.6%). At diagnosis, mean (±SD) 9.3 (7.5) years 15/17 (88.2%) available met ≥5 8 HLH-2004 diagnostic criteria. Underlying triggers 53/57 (92.9%) patients; 22/53 (41.5%) single trigger 31/53 (58.5%) multiple triggers. Infections (32/53; 60.4%), malignancy (18/53; 34%), rheumatologic (11/53; 20.8%), iatrogenic (6/53; 11.3%) most common Epstein-Barr virus (11/25; 44%) viral (25/32; 78.1%) infection. initiation, 73.7% received prior treatments other HLH-related therapies, including corticosteroids, 62.5% intensive care unit. mainly initiated refractory (42.1%), (29.8%), recurrent (14%) disease. median (range) 16.5 (1-2278) days. Median duration 38.0 (1-397) starting 1.1 (0.7-5.9) mg/kg cumulative 21.3 (1-336.5) mg/kg. maximum administered 2.3 (0.7-12.5) Conclusion This first report diverse patient population sHLH. pivotal trial ongoing ( NCT05001737 ). References [1]Allen CE, McClain KL. Hematology Am Soc Hematol Educ Program . 2015;2015:177-182. [2]Jordan MB, et al. Blood 2011;118:4041-4052. [3]Hatterer E, Cytokine 2012;59:570. [4]US Food Drug Administration. https://www.fda.gov/drugs/fda-approves-emapalumab-hemophagocytic-lymphohistiocytosis Accessed August 2, 2022. [5]Locatelli F, N Engl J Med 2020;382:1811-1822. Acknowledgements authors thank Sajjad Raza Alice Pressman (PRECISIONheor) Corey Best (Sobi, Inc) their support. Editorial writing support provided Sonali K. Kalra, PhD, rareLife solutions, Westport, CT, USA, funded Sobi, Inc. Disclosure Interests Carl Allen Consultant of: Inc., Shanmuganathan Chandrakasan Michael Jordan Jennifer Leiding Employee bluebird bio, Abiola Oladapo Priti Pednekar Kelly Walkovich John Yee