Breast Cancer : HER2-enriched
Molecular Subtypes of Breast Cancer - HER2-enriched: This subtype comprises 10% to 15% of all breast cancers. They are high-grade (as shown here), may have apocrine features, and show overexpression of HER2 cluster and proliferation-associated genes and lower expression of ER-related genes. In contrast to the luminal subtypes, the HER2-enriched breast cancers have a high frequency of mutations in TP53 (72%) and PIK3CA (39%). However, they have a much lower frequency of other significantly mutated genes. Most breast cancers in HER2-enriched molecular category show high levels of HER2 by immunohistochemistry (as shown here) and/or FISH; however, exceptions do occur in both directions. Treatment of HER2-enriched Breast Cancer: The monoclonal antibodies trastuzumab and pertuzumab, the tyrosine kinase inhibitor lapatinib and the antibody-drug conjugate trastuzumab emtansine are approved for HER2 positive breast cancer.