We then assessed the target selectivity of the corresponding anti-EGFR/HER2 bsAb variants, formatted either as monovalent bispecific IgG (DuetMab) or bivalent bispecific in IgG-scFv format25 by measuring their ability to selectively target and eradicate the “target tumor” over the non-target “normal tissue” cells on the opposite flank. This evidence concerns the gene ERBB2 and neoplasm.