Several therapies have been approved for the treatment of HER2-positive (HER2+) breast cancers: Lapatinib, a dual-targeting (EGFR/HER2) reversible TKI; Trastuzumab (Hercepin), a humanised mAb that binds to domain IV of the HER2 receptor; Pertuzumab (Perjeta) another humanised mAb that binds to domain II of the HER2 receptor; and Trastuzumab emtansine (Kadcyla or T-DM1), a conjugate of Trastuzumab and the cytotoxic drug DM115–17. Here, ERBB2 is linked to breast cancer.