1) HER2 positive breast cancer accounts for around 15-20% of cases and has a poorer prognosis than other subtypes without HER2 targeted therapy.
2) Multiple HER2 targeted agents are available including trastuzumab, lapatinib, pertuzumab, T-DM1, neratinib, and tucatinib which inhibit HER2 signaling through different mechanisms such as antibody binding or tyrosine kinase inhibition.
3) Combining HER2 targeted therapies such as trastuzumab with chemotherapy improves outcomes for patients with metastatic HER2 positive breast cancer compared to chemotherapy alone.