For example, even though HER2 T-BsAbs were more effective in treating SW1990 tumors than EGFR T-BsAbs, pairing the HER2 Fab with the less effective EGFR Fab in the heterodimeric EGFRxHER2 BsAb did not significantly diminish the overall anti-tumor efficacy. The gene discussed is ERBB2; the disease is neoplasm.