This is an exciting time in metastatic breast cancer research. Many new treatments for metastatic breast cancer are under study and treatment is improving.
Findings from clinical trials will determine whether or not new treatments will become a part of standard care for metastatic breast cancer.
Some treatments may even go on to be used for early stage breast cancer care.
Learn about clinical trials for people with metastatic breast cancer and access a web-based personalized clinical trial matching tool - the Metastatic Trial Search.
CDK4 and CDK6 are enzymes important in cell division. CDK4/6 inhibitors are a class of drugs designed to interrupt the growth of cancer cells.
Abemaciclib (Verzenio), palbociclib (Ibrance) and ribociclib (Kisqali) are CDK4/6 inhibitors FDA-approved for breast cancer treatment. They are used in combination with hormone therapy to treat hormone receptor-positive, HER2-negative metastatic breast cancers.
Other CDK4/6 inhibitors are under study for use in metastatic breast cancer treatment.
About 10-20 percent of breast cancers have high amounts of a protein called HER2 on the surface of the cancer cells (called HER2-positive breast cancer) [18-19]. The HER2 protein is important for cancer cell growth.
Trastuzumab (Herceptin) and pertuzumab (Perjeta) are special antibody drugs designed to target HER2-positive cancer cells. These drugs are FDA-approved for the treatment of HER2-positive breast cancers.
Other HER2-targeted antibody drugs, such as margetuximab, are under study .
Special antibody drugs are designed to target certain cancer cells. Antibody-drug conjugates are a combination of an antibody therapy and a chemotherapy drug. Combining these into one drug allows the targeted delivery of the chemotherapy to specific cancer cells.
The antibody drug trastuzumab (Herceptin) is designed to target HER2-positive cancer cells.
The antibody-drug conjugates ado-trastuzumab emtansine (Kadcyla, T-DM1, trastuzumab emtansine) and fam-trastuzumab deruxtecan-nxki (Enhertu) are FDA-approved for the treatment of HER2-positive metastatic breast cancer.
Other antibody-drug conjugates are under study for the treatment of metastatic breast cancers. These include other HER2 antibody drug conjugates as well as Trop-2 antibody-drug conjugates [55,82].
Tyrosine kinase inhibitors are a class of drugs that target enzymes important for cell functions (called tyrosine-kinase enzymes).
These drugs can block tyrosine-kinase enzymes at many points along the cancer growth pathway.
Tyrosine-kinase inhibitors include neratinib (Nerlynx), which is FDA-approved for the treatment of HER2-positive early breast cancer, and lapatinib (Tykerb), which is FDA-approved for the treatment of HER2-positive metastatic breast cancer.
Other tyrosine kinase inhibitors, including tucatinib and neratinib, are under study for use in metastatic breast cancer treatment.
A recent study showed adding tucatinib to treatment with trastuzumab (Herceptin) and the chemotherapy drug capecitabine (Xeloda) may increase overall survival in some people with HER2-positive metastatic breast cancer .
PI3 kinase is an enzyme important in cell growth. The PIK3CA gene helps control PI3 kinase enzyme activity.
Some breast cancers have a mutation in the PIK3CA gene (this gene mutation is in the genes of breast cancer, not the person). This mutation can affect PI3 kinase and cause the tumor to grow.
PI3 kinase inhibitors are a class of drugs designed to interrupt PI3 kinase signals and stop the growth of cancer cells.
The PI3 kinase inhibitor alpelisib (Piqray) is used to treat some metastatic breast cancers that have a mutation in the PIK3CA gene and are hormone receptor-positive and HER2-negative .
Other PI3 kinase inhibitors are under study.
Poly(ADP-ribose) polymerase (PARP) inhibitors are a class of drugs under study for many types of cancer, including breast cancer.
PARP is an enzyme involved in DNA repair. Some chemotherapy drugs damage tumor DNA. PARP inhibitors work to stop PARP from repairing tumor DNA to help the chemotherapy kill the cancer cells.
PARP inhibitors are only used in breast cancer treatment for people who have a BRCA1 or BRCA2 gene mutation. BRCA1/2-related breast cancers seem to be sensitive to DNA damage involving the PARP enzyme.
PARP inhibitors are not used to treat metastatic breast cancer in people who do not have a BRCA1 or BRCA2 gene mutation.
The PARP inhibitors olaparib (Lynparza) and talazoparib (Talzenna) are FDA-approved for the treatment of HER2-negative metastatic breast cancer in people who have a BRCA1/2 gene mutation.
Other PARP inhibitors are under study for use in metastatic breast cancer treatment.
Drugs that help the body’s immune system attack cancer cells are now used to treat many cancers (including melanoma, lung cancer, bladder cancer and kidney cancer).
Overall, immunotherapy drugs (including vaccines) are not as promising for breast cancer compared to other cancers at this time. However, they may be effective in treating some breast cancers.
Researchers are studying how to identify the best biomarkers for immunotherapy.
“Checkpoint inhibitors” are one type of immunotherapy drug. These drugs “take the brakes off” the natural factors that limit how the immune system can control tumor cells.
The checkpoint inhibitor immunotherapy drug atezolizumab (Tecentriq) is FDA-approved for the treatment of metastatic triple negative breast cancer that express (have a lot of) programmed cell death protein 1 (PD-L1) .
Many other types of immunotherapy drugs, including the checkpoint inhibitor pembrolizumab, are under study for metastatic breast cancer treatment .
The checkpoint inhibitor immunotherapy drug pembrolizumab is under study for the treatment of metastatic triple negative breast cancer .
Some triple negative cancer cells have a receptor that limits the action of the protein called programmed cell death protein 1 (PD-1). Pembrolizumab may help take the brakes off PD-1 to allow the body to kill more cancer cells .
Other immunotherapy drugs are under study.
Some breast cancers have cells with higher levels of the protein Trop-2 than other breast cancers (they express Trop-2). Triple negative breast cancers tend to express Trop-2.
Sacituzumab govitecan (sa-si-TOO-zoo-mab goh-vee-TEE-can) is an antibody-drug conjugate that combines a Trop-2 antibody and the chemotherapy drug irinotecan. This combination allows the targeted delivery of iriotecan to cancer cells that express Trop-2.
Sacituzumab govitecan is under study for the treatment of metastatic triple negative breast cancer .
Histone deacetylase (HDAC) inhibitors are a class of drugs that target enzymes important for some cell functions (called HDAC enzymes).
These drugs can block HDAC enzymes on the cancer growth pathway. This may slow tumor growth and lead to tumor cell death.
Some HDAC inhibitors, such as the selective HDAC inhibitor tucidinostat, are under study for the treatment of metastatic breast cancer .
Anti-angiogenesis drugs block the growth of new blood vessels (angiogenesis). Without a blood supply, the cancer cannot grow.
Although early data showed the anti-angiogenesis drug bevacizumab (Avastin) benefited some women with metastatic breast cancer, longer-term follow-up data did not confirm these findings. In 2011, the FDA withdrew its approval for the use of bevacizumab in the treatment of metastatic breast cancer .
However, other anti-angiogenesis drugs are still under study for the treatment of metastatic breast cancer.
Bevacizumab remains FDA-approved for use in other cancers.
Tumors often develop resistance (stop responding) to drugs used to treat metastatic breast cancer.
New ways to monitor response to treatment are under study.
Circulating tumor cell levels can help predict survival for people with metastatic breast cancer [58-59].
The more circulating tumor cells in the blood, the more advanced the metastatic breast cancer is likely to be.
Having more circulating tumor cells may also predict a lack of response to treatment.
Similarly, circulating tumor DNA is under study for use in monitoring metastatic breast cancer and predicting treatment response [60-62].
At this time, circulating tumor cell and circulating tumor DNA tests (sometimes called liquid biopsies) should not be used to guide treatment because they haven't been shown to offer benefit [63-66].
However, these topics are under study.
Our commitment to research
At Susan G. Komen®, we are committed to saving lives by meeting the most critical needs in our communities and investing in breakthrough research to prevent and cure breast cancer. Our Research Program is an essential driving force for achieving this mission.
Since our inception in 1982, Komen has provided funding to support research grants that have greatly expanded our knowledge of breast cancer and helped us understand that breast cancer is not just a single disease but many diseases, unique to each individual.
Going forward, our commitment to research will contribute significantly to our ability to achieve our Bold Goal of reducing the current number of breast cancer deaths in the U.S. by 50 percent by 2026.
To date, Komen has provided more than $988M to researchers in 47 states, the District of Columbia and 22 countries to support research that has resulted in a better understanding of breast cancer; earlier detection; personalized, less invasive treatments for what was once a “one-treatment-fits-all” disease; and improvements in both quality of life and survival rates.
Learn more about our continuing investment in research and the exciting research that we are funding, because nothing would make us happier than ending breast cancer forever.
After talking with your health care provider, we encourage you to consider joining a clinical trial for metastatic breast cancer.
If your medical center does not offer clinical trials, you may want to get a referral to a cancer center that does.
BreastCancerTrials.org in collaboration with Susan G. Komen® offers a web-based personalized clinical trial matching tool - the Metastatic Trial Search. This tool makes finding out about metastatic breast cancer clinical trial options easy and fast.
Learn more about clinical trials for people with metastatic breast cancer and find a list of resources to help you find a clinical trial.
Susan G. Komen® Breast Cancer Clinical Trial Information Helpline
If you or a loved one needs information or resources about clinical trials, call our Clinical Trial Information Helpline at 1-877 GO KOMEN (1-877- 465- 6636) or email firstname.lastname@example.org.
The helpline offers breast cancer clinical trial education and support, such as:
What is Susan G. Komen® doing?
Susan G. Komen® is one of several organizations that supported the Reagan-Udall Foundation and the Food and Drug Administration (FDA) in the development of the Expanded Access Navigator website.
Expanded Access (EA) is also known as “compassionate use.” It gives patients access to drugs before they have FDA approval. This may be needed when patients have exhausted their treatment options and who are not eligible for (or unable to participate in) a clinical trial.
The Expanded Access (EA) Navigator tool serves as a clearinghouse of information and resources to help patients and their doctors more easily access information that could impact treatment decisions. The EA Navigator explains what EA is, who may be eligible, how the request process works and the regulatory and policy issues around EA.
The EA Navigator also contains the pharmaceutical companies EA policies. The open EA programs are listed on the National Institutes of Health’s clinical trials website, www.clinicaltrials.gov.
Learn more about what Komen is doing to help people with metastatic breast cancer.
*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.
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