509 AMG487, A CXCR3 Antagonist, changes the Inflammatory Milieu in Familial Hemophagocytic Lymphohistiocytosis (FHL) Hepatitis

OBJECTIVES/GOALS: Familial Hemophagocytic Lymphohistiocytosis (FHL) is a systemic inflammatory disease, causing acute liver failure (ALF). Elevated Interferon gamma (IFN-γ) results in increased hepatic transcription of the chemokines CXCL9 and CXCL10. Inhibition of their receptor CXCR3 may reduce leukocyte recruitment and ameliorate hepatitis. METHODS/STUDY POPULATION: To determine the functional role of the IFN-γ-induced ligands, CXCL9 and CXCL10, in hepatic leukocyte recruitment via CXCR3 we used a prf-/- mouse infected with Lymphocytic Choriomeningitis Virus (LCMV) in our well-established model mimicking human FHL. We used AMG487, a small molecule CXCR3 antagonist, while maintaining intact IFN-γ signaling. Mice were sacrificed 10 days after infection when mice developed features of FHL: cytopenias, organomegaly, elevated serum ferritin and sCD25, and hepatic inflammation. Hepatic inflammation was characterized using flow cytometry, liver histology and noninvasive markers of hepatitis (ALT, liver size). RESULTS/ANTICIPATED RESULTS: AMG487 did not ameliorate the overall disease phenotype with mice developing similar FHL characteristics compared to control, including weight loss, elevation of ALT and sIL-2r as well as degree of thrombocytopenia and anemia. There was significant reduction of recruitment of CXCR3+CD4+ T cells and B cells in mice treated with AMG487. This indicates the importance of CXCR3 receptor in humoral response in FHL hepatitis. In addition, treatment with AMG487 resulted in reduction of CXCR3 expression in hepatic inflammatory monocyte (iMonos) measured by mean fluorescence intensity (MFI). DISCUSSION/SIGNIFICANCE: This is the first pre-clinical experience using AMG487, a small molecule CXCR3 antagonist, to treat FHL hepatitis. AMG487 changed the hepatic inflammatory milieu, reducing CD4 T-cell and B-cell recruitment, as well as CXCR3 expression on iMonos. However, it did not ameliorate FHL hepatitis and other therapeutic approaches should be pursued.