New targets in breast cancer

In the past few years, the therapeutic strategies for breast cancer have broadened substantially beyond endocrine therapy, chemotherapy, and human epidermal growth factor receptor 2-targeted agents to include several new drugs with unique mechanism of actions including antibody–drug conjugates, inhibitors of the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin pathway, cyclin-dependent kinases 4/6, histone deacetylases and the poly ADP ribose polymerase as well as immune checkpoint modulators. Novel clinical trial designs are also being implemented in the clinic to assess the therapeutic potential of targeting rare molecular abnormalities observed in breast cancers (fibroblast growth factor receptor amplification, inactivating mutations in BRCA, activating mutations in HER2, epidermal growth factor receptor, c-Kit, Akt, etc.).