Doctors define different types (subtypes) of MBC depending on whether cancer has or does not have three markers—estrogen receptor (ER), progesterone receptor (PR), and HER2. Doctors then use the subtype and other information to recommend a person’s treatment. This month, we continue our series about MBC subtypes and expert thoughts on the subtype.
Triple negative MBC is negative for ER, PR, and HER2 and is typically treated with immunotherapy, chemotherapy, and/or targeted therapy. Some people with triple negative MBC express low or ultralow levels of HER2 and may be eligible for treatments that target HER2. Read below for the latest expert opinions on treatments, and some questions that need to be answered in clinical trials.
Introduction to Triple Negative MBC
- Living Beyond Breast Cancer: Around 10-15% of MBC is triple negative, and this subtype is more aggressive than other subtypes
Experts Weigh in on Triple Negative MBC
- Susan G Komen (video): Dr. Melina Telli describes the latest research and treatments for triple negative MBC
- Triple Negative Breast Cancer Foundation (video): Dr. Rita Nanda and Dr. Lisa Carey discuss research and living with triple negative MBC
Experts Weigh in on Triple Negative MBC That is HER2 Ultralow
- FORCE: Some people with triple negative MBC have low amounts of HER2 in their tumors, called HER2-low, and may receive treatment with the HER2 targeted therapy, trastuzumab deruxtecan (T-DXd; Enhertu®)
- Mayo Clinic: Dr. Roberto Leon-Ferre explains that breast cancer with very small amounts of HER2, called HER2 ultralow, can be treated with HER2 targeted therapy
MBC Clinical Trials
- Metastatic Trial Search: Trials Specifically for People with HER2-Negative MBC
- Metastatic Trial Search: Trials Specifically for People with HER2-Low and HER2-Ultra Low MBC
Last Modified on January 7, 2026