Expression and targeting of human fibroblast activation protein in a human skin/severe combined immunodeficient mouse breast cancer xenograft model.

Antigens and receptors that are highly expressed on tumor stromal cells, such as fibroblast activation protein (FAP), are attractive targets for antibody-based therapies because the supporting stroma and vessel network is essential for a solid neoplasm to grow beyond a size of 1-2 mm. The in vivo characterization of antibodies targeting human stromal or vessel antigens is hindered by the lack of an appropriate mouse model system because xenografts in standard mouse models express stromal and vessels elements of murine origin. This limitation may be overcome by the development of a human skin/mouse chimeric model, which is established by transplanting human foreskin on to the lateral flank of severe combined immunodeficient mice.