The bispecific targeting tumor-associated antigens, such as HER2/CD3 against HER2-positive breast cancer or TROP2/CD3 against triple-negative breast cancer, would potentially activate the immune cells further by directing T cells against tumors instead, whereas trispecific designs would target various antigens from several tumor antigens simultaneously to counteract antigen escape, as in the case of HER2/EGFR/MUC1 for breast cancer or mesothelin/CA19-9/CD3 in pancreatic cancer (Figure 3) [57,58,59]. This evidence concerns the gene ERBB2 and breast carcinoma.