Moreover, BiTEs directed against antigens expressed on tumor and effector T cells, such as CD45 or HLA-A2 if HLA-A2-positive T cells are interrogated, induced massive fratricide reactions, indicating that co-expression of potential candidate target antigens on T lymphocytes may further limit the therapeutic scope of BiTE constructs (Fig. 2e). This evidence concerns the gene PTPRC and neoplasm.