Therapeutic Response

ER positive and HER2-ultralow status confers therapeutic sensitivity to Trastuzumab deruxtecan in patients with Invasive Breast Carcinoma.

Statements

Source and description

Enhertu (trastuzumab deruxtecan) [package insert]. FDA. The U.S. Food and Drug Administration granted approval to fam-trastuzumab deruxtecan-nxki, as monotherapy, for the treatment of adult patients with unresectable or metastatic hormone receptor-positive HER2-low (immunohistochemistry 1+ or immunohistochemistry 2+/in situ hybridization-negative) or HER2-ultralow (immunohistochemistry 0 with membrane staining) breast cancer, as determined by an FDA-authorized test, that has progressed on one or more endocrine therapies in the metastatic setting. This indication is based on DESTINY-Breast06, in which HER2-ultralow was defined as membrane staining that was seen in greater than 0 and less than or equal to 10% of tumor cells.