The desire to mimic the T-effector cell (e.g., the CTL) binding via its TCR to the MHC/tumor peptide target on a tumor target cell drove the development of naptumomab estafenatox, which showed distinct characteristics regarding binding to the tumor antigen (5T4), the TCR, and the MHC class II proteins [12••, 13]. This evidence concerns the gene TPBG and neoplasm.