Breast cancer research
Metastatic breast cancer (mBC)
How do targeted therapies work as breast cancer treatment?
Hormone receptor (HR) status and breast cancer
- HR-positive (HR+) breast cancer is a subtype that involves tumor cells with receptors for the estrogen or progesterone hormones, which can promote tumor growth
- HR+ breast cancers tend to grow more slowly than those that are hormone receptor-negative (HR–) and can be treated with hormone therapy drugs
- HR+ breast cancer makes up about 80% of all female breast cancer cases
- HR– breast cancer cells do not have estrogen or progesterone receptors and tend to grow faster than HR+ cancers
- HR– breast cancer makes up approximately 15% of all female breast cancer cases
Human epidermal growth factor receptor 2 (HER2) status and breast cancer
- HER2-positive (HER2+) breast cancer is a subtype with the overexpression of the HER2 protein, which can help breast cancer develop more quickly
- About 15-20% of breast cancers have higher amounts of HER2 and have a better chance of responding to HER2-targeted medicines
- Up to 50% of women with HER2+ mBC may develop brain metastases, which is higher than in other breast cancer subtypes
- Breast cancers that do not overexpress the HER2 protein are classified as HER2-negative (HER2–). This subtype makes up over 80% of female breast cancer cases
With new treatments being approved for HER2-low and ultra-low breast cancer, which have lower levels of HER2 protein expression, there is potential for further development of additional therapies targeting HER2 tumors.
Pfizer’s breast cancer treatments
Pfizer has several approved targeted medicines for certain subtypes of breast cancer, based on specific biomarkers. Some of these medicines include CDK4/6 inhibitors, kinase inhibitors, and PARP inhibitors.
Pfizer is working on new potential medicines across different types of breast cancer including HR+/HER2- and HER2+ breast cancer. We are also exploring innovative targets to overcome challenges with medication resistance, which happens when the breast cancer no longer responds to other anticancer drugs. With these new medicines, we hope to further improve outcomes for people living with breast cancer.
Explore related topics
Biomarker tests for treatment
Biomarkers are specific genes or proteins that can be found in the body where cancer is present. They help doctors diagnose and may help more accurately treat cancer.
Breast cancer screening saves lives
If breast cancer is found early, when it’s small and has not spread, it can be easier to treat successfully. Learn about screening.
The future of cancer treatment starts here
Pfizer’s pipeline is advancing precision medicines in breast cancer and working to address treatment resistance.