HER2-positive breast cancer: trastuzumab, lapatinib and emerging therapies

The discovery of the HER2 alteration in 20–25% of breast cancers has ushered in an era of molecularly targeted therapies. Targeting HER2 with antibody-based approaches, such as trastuzumab, or tyrosine kinase inhibitors, such as lapatinib, has yielded improvements in clinical outcomes. Nevertheless, mechanisms of actions underlying anti-HER2 therapies are incompletely understood, and drug resistance is frequently encountered in the clinic. In this review, standard-of-care and emerging therapies in HER2-positive breast cancer will be discussed, with a focus on strategies in late-phase clinical development.