ERBB2 and breast cancer: In contrast, the humanized antibody trastuzumab, which is the standard of care for patients with early and advanced HER2-positive BC, was found to bind d16HER2 to a lesser extent than full-length HER2 counterpart in HEK-293 transfectants, reflecting a lack of reactivity with d16HER2 homodimers that can be reverted in the presence of a reducing agent able to break disulfide bridges.