Abstract A78: Analysis of ROR1 protein expression in mice with reconstituted human immune system components

Abstract

Abstract Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal antigen expressed on multiple solid tumors and leukemias, but not on normal human tissues except at very low levels in adipose tissue. ROR1 is highly upregulated in chronic lymphocytic leukemia (CLL) B cells. NOD-scid IL2rγnull (NSG) mice engrafted with human fetal liver CD34+ hematopoietic progenitor cells (huNSG) achieved multi-lineage human immune cell reconstitution including B cells, T cells, NK cells and Dendritic cells. Like the CLL patients, most of huNSG mice have abnormal high frequency of B cells in the periphery, and a percentage of CD19+ B cells express CD5. In light of this, we aim to determine whether ROR1 is expressed in B cells of huNSG mice, we analyzed the protein level of ROR1 in B cells of huNSG mice by flow cytometry. ROR1 protein was highly expressed in a proportion of B cells in the blood, spleen and bone marrow. As huNSG mice have autologous T and NK cells, plus the B cells with ROR1 expression, this could act as a B cell malignant disease model for studying immunotherapeutic targeting ROR1, including bispecific T cell engagers and chimeric antigen receptor T cells. Citation Format: Carol SK Leung. Analysis of ROR1 protein expression in mice with reconstituted human immune system components [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A78.