Therapeutic Response Statement (Sensitivity)

This therapeutic response statement Supports the relationship that HER2-ultralow and PR positive status confers therapeutic sensitivity to Trastuzumab deruxtecan in patients with Invasive Breast Carcinoma.

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.

This statement is based on a regulatory approval from the Food and Drug Administration:

ENHERTU is a HER2-directed antibody and topoisomerase inhibitor conjugate indicated, as monotherapy, for the treatment of adult patients with unresectable or metastatic hormone receptor (HR)-positive HER2-low (IHC 1+ or IHC 2+/ISH-) or HER2-ultralow (IHC 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.

Citation

Daiichi Sankyo. Enhertu (fam-trastuzumab deruxtecan-nxki) [package insert]. U.S. Food and Drug Administration website. https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/761139s041s043lbl.pdf. Revised May 2026. Accessed October 8, 2026. Daiichi Sankyo, Inc. Enhertu (trastuzumab deruxtecan) [package insert]. U.S. Food and Drug Administration website. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761139s032s035lbl.pdf. Revised January 2025. Accessed October 6, 2026.

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Contributions

Date Contributor Description
2026-10-08 Van Allen lab Initial curation of this indication into moalmanac-db.
2025-01-27 Food and Drug Administration Indication received traditional approval.