UCLA

Epstein-Barr virus (EBV) is a human gammaherpesvirus associated with the development of hematopoietic cancers of B-lymphocyte origin, including AIDS-related non-Hodgkin lymphoma (AIDS-NHL). Primary infection of B-cells with EBV results in their polyclonal activation and immortalization. The transferrin receptor 1 (TfR1), also known as CD71, is important for iron uptake and regulation of cellular proliferation. TfR1 is highly expressed in proliferating cells, including activated lymphocytes and malignant cells. We developed a mouse/human chimeric antibody targeting TfR1 (ch128.1/IgG1) that has previously shown significant antitumor activity in immunosuppressed mouse models bearing human malignant B-cells, including multiple myeloma and AIDS-NHL cells. In this article, we examined the effect of targeting TfR1 to inhibit EBV-driven activation and growth of human B-cells in vivo using an immunodeficient NOD.Cg-Prkdc^scid Il2rg^tm1Wjl /SzJ [NOD/SCID gamma (NSG)] mouse model. Mice were implanted with T-cell-depleted, human peripheral blood mononuclear cells (PBMCs), either without EBV (EBV^-), or exposed to EBV in vitro (EBV⁺), intravenously via the tail vein. Mice implanted with EBV⁺ cells and treated with an IgG1 control antibody (400 μg/mouse) developed lymphoma-like growths of human B-cell origin that were EBV⁺, whereas mice implanted with EBV⁺ cells and treated with ch128.1/IgG1 (400 μg/mouse) showed increased survival and significantly reduced inflammation and B-cell activation. These results indicate that ch128.1/IgG1 is effective at preventing the growth of EBV⁺ human B-cell tumors in vivo, thus, indicating that there is significant potential for agents targeting TfR1 as therapeutic strategies to prevent the development of EBV-associated B-cell malignancies. SIGNIFICANCE: An anti-TfR1 antibody, ch128.1/IgG1, effectively inhibits the activation, growth, and immortalization of EBV⁺ human B-cells in vivo, as well as the development of these cells into lymphoma-like tumors in immunodeficient mice.