Breast Cancer
Biomarkers and Targeted Treatment for Breast Cancer
Biomarker testing looks at either genes or proteins that may be present in the tumor. This testing guides the best treatment by offering specific treatment only for those individuals who will benefit from that treatment. This avoids the need to give everyone the same treatment since all breast cancers are different.
What are Biomarkers?
What is HER2Low?
The first biomarker tests that are done on all breast cancers include testing for the presence of estrogen receptors (ER) and progesterone receptors (PR). Normal breast cells, as well as many other cells in the body, express these receptors, so that estrogen and progesterone hormones that travel in our bodies can respond to the hormones. This is good; it is part of what makes it possible for women to become pregnant and breastfeed. When someone has breast cancer, the cell division and growth that is a result of hormone binding may lead the cancer to grow faster. In cancers that have these ER and PR receptors, medications can be taken that can limit the ability of estrogen and progesterone to stimulate cancer cell division and growth.
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Newly diagnosed breast cancers are also checked for her2neu. Her2neu is a growth factor receptor that is normally present on the cell surface. Sometimes cancer cells have significantly more of these receptors, and those breast cancers are then call her2 positive. People with her2 positive breast cancer are eligible to use Herceptin and other her2 targeted treatments.
There are other biomarkers that may be tested later on if the breast cancer is advanced, or is recurrent. These include PD-L1 protein expression, PIK3CA mutations in the tumor itself, or BRCA1/BRCA2 mutations that are either hereditary, or found in the tumor itself. Cerianna is an imaging agentfor the visual detection of estrogen receptor (ER) positive lesions as an adjunct to biopsy in patients with recurrent or metastatic breast cancer. It is injected into a vein by a healthcare provider in preparation for an imaging test (PET scan) to detect the lesions. These biomarkers and related treatments are detailed in the following pages.
Be sure to ask your doctor about any concerns you may have about biomarkers and targeted treatment. To learn more, please contact a member of our Sharsheret support team at 866.474.2774 or sharsheret.org.
Find Biomarkers
ER/PR Biomarkers and Associated Medications
| Drug name | Chemical name | Company | Indication | Action |
| Arimedex | Anastrozole(Aromatase Inhibitor or AI) | AstraZeneca | ER+ breast cancer for post-menopausal women | Prevents the formation of estrogen in post-menopausal women by blocking the enzyme aromatase |
| Aromasin | Exemestane(Aromatase Inhibitor or AI) | Pfizer | ER+ breast cancer for post-menopausal women | Prevents the formation of estrogen in post-menopausal women by blocking the enzyme aromatase |
| Femara | Letrozole(Aromatase Inhibitor or AI) | Novartis | ER+ breast cancer for post-menopausal women | Prevents the formation of estrogen in post-menopausal women by blocking the enzyme aromatase |
| Nolvadex | Tamoxifen | AstraZeneca | ER+ breast cancer or women at high risk for breast cancer | SERM, or selective estrogen receptor modulator; selectively blocking or activating estrogens effects on different cells |
| Evista | Raloxifene | Eli Lilly | ER+ breast cancer or women at high risk for breast cancer | SERM, or selective estrogen receptor modulator; selectively blocking or activating estrogens effects on different cells |
| Faslodex | Fulvestrant | AstraZeneca | ER+ breast cancer at advanced stage, or if other hormonal treatments are not working | ERD, or estrogen receptor (ER) downregulator binds to the ER to prevent estrogen from binding, may also impair the ER |
| Zolodex | Goserelin | AstraZeneca | ER+ early stage breast cancer in premenopausal women | Shuts down the ovaries to stop them from producing estrogen |
| Afinitor | Everolimus | Novartis | ER+ breast cancer that stops responding to an AI | mTOR (kinase) inhibitor; stops cancer cells from getting the energy they need to grow |
| Ibrance | Pablociclib | Pfizer | ER+ advanced stage or metastatic breast cancer | CDK (cyclin dependent kinase) inhibitor that interferes with kinases that help cancer cells to divide and grow |
| Kisqali | Ribociclib | Novartis | ER+, her2 neg breast cancer; used with another hormonal agent | CDK (cyclin dependent kinase) inhibitor that interferes with kinases that help cancer cells to divide and grow |
| Verzenio | Abemaciclib | Eli Lilly | ER+, her2 neg breast cancer, in combination with a hormonal treatment | CDK (cyclin dependent kinase) inhibitor that interferes with kinases that help cancer cells to divide and grow |
| Orserdu | Elacestrant | Stemline Therapeutics, Menarini Group | ER+, her2 neg, ESR1 mutated advanced metastatic breast cancer | SERD (selective estrogen receptor downgrader or downregulator) binds and degrades the estrogen receptor |
| Cerianna | Fluoroestradiol F 18 | GE Healthcare | Recurrent or metastatic breast cancer | Administered as a single intravenous injection for PET imaging to detect ER+ lesions as an adjunct to biopsy in patients with recurrent or metastatic breast cancer |
HER2neu Biomarkers and Associated Medications
| Drug name | Chemical name | Company | Indication | Action |
| Herceptin | Trastuzumab | Genentech | HER2+ breast cancer | Attaches to the HER2 receptor, preventing it from receiving growth signals |
| Enhertu | Trastuzumab deruxtecan | Daiichi-Sankyo | Low level Her2+ advanced stage breast cancer that is not responding to treatment (Her2 low) | Attaches to the HER2 receptor, preventing it from receiving growth signals; also interferes with the cells ability to replicate |
| Hylecta | Trastuzumab docetaxel | Roche | Her2+ advanced stage breast cancer that is not responding to treatment | Attaches to the HER2 receptor and helps the body use Herceptin |
| Kadcyla | Ado-trastuzumab emtansine | Genentech | Her2+ breast cancer; metastatic, or for residual disease after neoadjuvant chemo and surgery | Attaches to the HER2 receptor and locally delivers emtansine, which disrupts cell growth; emtansine is too toxic when taken alone. |
| Margenza | Margetuximab-cmkb | Macrogenics | Metastatic her2+ breast cancer treated with at least 2 other her2+ regimens | Attaches to the HER2 receptor, preventing it from receiving growth signals; also improves the ability of immune cells to bind to and destroy cancer cells |
| Nerlynx | Neratinib | Puma Bio-technology | Her2+ breast cancer given after treatment with Herceptin to extend the impact | Irreversible pan her2 inhibitor, not an antibody, used with Xeloda to block the cancer cells ability to receive growth signals |
| Perjeta | Pertuzumab | Genentech | Her2+ breast cancer in combination with Herceptin and chemotherapy | Blocks a different part of the her2 receptor than Herceptin, leading to a stronger block; Herceptin and Perjeta are complementary |
| Phesgo | Pertuzumab, trastuzumab, & hyaluronidase-zzxf | Genentech | Her2+ breast cancer in combination with Herceptin, Perjeta, and chemotherapy | Hyaluronidase-zzxf is an enzyme that helps the body absorb Herceptin and Perjeta, see above |
| Tukysa | Tucatinib | Seattle Genetics | Unresectable, locally advanced or metastatic Her2+ breast cancer | Tyrosine kinase inhibitor that blocks a specific area of the her2 receptor; stops cancer cells from growing and spreading |
| Tykerb | Lapatinib | Novartis | Her2+ advanced stage breast cancer that is not responding to treatment | Works by interfering with HER2-related kinases inside the cell (not the receptor), limiting the energy cancer cells have to grow and multiply |
Other Biomarkers and Associated Medications
| Drug name | Chemical name | Company | Indication | Action |
| Avastin | Bevacizumab | Genentech | Metastatic HER2 neg breast cancer in 2008; FDA removed indication in 2011, but doctors may still use it | Blocks the growth of new blood vessels that help supply the growing tumor |
| Keytruda | Pembrolizumab | Merck | Recurrent, unresectable triple-negative breast cancer and tests positive for PD-L1 | Binds to the protein PD-1 to help the immune cells fight cancer |
| Tecentriq | Atezolizumab | Genentech | Recurrent, unresectable triple-negative breast cancer and tests positive for PD-L1; It is also used in combination with paclitaxel | Binds to the protein PD-1 to help the immune cells fight cancer |
| Piqray | Alpelisib | Novartis | ER+, her2 neg advanced stage or metastatic breast cancer with a PIK3CA mutation | Mutations in PIK3CA over activate the PI3k pathway; PI3K inhibitor blocks the PI3K pathway that helps cancer cells survive and grow. |
| Itovebi | Inavolisib | Genentech | ER+, her2 neg advanced stage or metastatic breast cancer with a PIK3CA mutation | Mutations in PIK3CA over activate the PI3k pathway; PI3K inhibitor blocks the PI3K pathway that helps cancer cells survive and grow. |
| Lynparza | Olaparib | AstraZeneca | Metastatic her2 neg breast cancer and an inherited BRCA1/2 mutation, previously treated with chemo | PARP (poly ADP-ribose polymerase) inhibitor that makes cells less likely to survive DNA damage from chemotherapy |
| Talzenna | Talazoparib | Pfizer | Metastatic or locally advanced her2 neg breast cancer and an inherited BRCA1/2 mutation | PARP (poly ADP-ribose polymerase) inhibitor that makes cells less likely to survive DNA damage from chemotherapy |
| Trodelvy | Sacituzumab govitecan-hziy | Gilead | Unresectable, locally advanced or metastatic triple negative breast cancer, who have received other regimens | Trodelvy has 2 parts: one targets the Trop-2 protein on 90% of triple negative breast cancer, the other is a topoisomerase I inhibitor chemotherapy, locally delivered to the cancer cells |
| Datroway | Datopotamab deruxtecan-dnlk | Daiichi Sankyo | AstraZeneca | Unresectable or metastatic, (HR)-positive, HER2-negative breast cancer who have received prior endocrine-based therapy and chemotherapy for unresectable or metastatic disease. | Two part chemo, one targets the Trop-2 protein, the other is a topoisomerase I inhibitor chemotherapy, locally delivered to the cancer cells |
| Zometa | Zoledronic acid | Novartis | Metastatic breast cancer which has spread to the bones. | Limits the activity of bone cells called osteoclasts, which helps minimize damage from bone metastasis |
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