Under current treatment guidelines, breast cancer is categorized as HER2-positive or HER2-negative. However, some investigators use the term HER2-low expressing (or HER2-low expression) in clinical trials and research to describe HER2-negative tumors that test IHC 1+ or 2+ and FISH-. These tumors contain some cancer cells with surface HER2 proteins.
New research shows that a HER2-antibody-drug conjugate (ADC), fam-trastuzumab deruxtecan-nxki (Enhertu®), offers clinical benefit to some people with HER2-low expression tumors. However, not all HER2-antibody-drug conjugates have shown anti-cancer activity in HER2-low expressing breast cancer. Clinical trials data suggests there is more to learn about HER2-ADCs and the treatment of HER2-low expressing breast cancer.
See the links below to learn more.
- Q&A with Sara M. Tolaney, MD, MPH: Testing and Treatment Advancements for Women With HER2-Positive Breast Cancer Defines HER2-low expressing breast cancer and discusses current limitations in HER2 testing.
- Dr. Hamilton on the Effectiveness of Trastuzumab Deruxtecan in HER2-Low Breast Cancer Explains how ADCs can also kill tumor cells they do not bind to–the “bystander effect.”
- Antibody-Drug Conjugates in HER2-Positive Breast Cancer OncLive presents information about the efficacy of ADCs in HER2-low expression breast cancer.
- HER2 Directed Antibody-Drug-Conjugates beyond T-DM1 in Breast Cancer A comprehensive journal article reviewing experimental and approved ADCs for HER2-positive and HER2-low expression breast cancer.
- HER2-Low Breast Cancer: Pathological and Clinical Landscape This journal requires a subscription , but this article is up-to-date and exclusively discusses HER2-low breast cancer.
- Clinical Trials Studying How to Treat Advanced or Metastatic HER2-low Breast Cancer See Clinical Trials from BreastCancerTrials.org and Metastatic Trial Search