FAP and cancer: Combinatorial strategies addressing the two key issues of cancer immunotherapy (ie. targeting the tumor cells and modulating the T-cell response), the production of a bio-specific single chain antibody (scFv) directed against FAP α and CD3 (T cell receptor component), and the subsequent construction of a bio-specific antibody combined with co-stimulatory antibody-ligand fusion proteins, show the potential for initiating and regulating immune response at the TME in addition to modulating tumor progress [68, 69].