Abstract
Trastuzumab, a monoclonal antibody against HER2, in combination with taxane-based chemotherapy is the standard for adjuvant therapy of patients with HER2- -positive breast cancer as well as the standard for first-line treatment of metastatic disease. Progression of the disease, however, is relatively frequently associated with the development of resistance to trastuzumab that is caused by different changes at molecular level.
Information regarding the mechanism of resistance is, at the same time, a precondition for correct choice of the option to overcome the resistance. It is currently possible to use two treatment strategies: change of the chemotherapy added to trastuzumab the administration of which can then be continued (adjuvant therapy), or second-line therapy with the tyrosine kinase inhibitor lapatinib (treatment of metastatic disease).
A promising option appears to be the use of trastuzumab emtansine (T-DM1), the combination trastuzumab plus pertuzumab, or trastuzumab plus everolimus. Other, entirely new molecules are in the phase of clinical evaluation.