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.
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 neratinib and tucatinib, are under study for use in metastatic breast cancer treatment.
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 treatment 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.
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.
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.
PI3 kinase inhibitors are under study for use in metastatic breast cancer treatment.
Some targeted therapies are special antibody drugs designed to target certain cancer cells. For example the drug trastuzumab (Herceptin) is a specially made antibody that targets HER2-positive cancer cells.
Antibody-drug conjugates are a combination of an antibody targeted therapy drug and a chemotherapy drug. The combination allows the targeted delivery of chemotherapy to certain cancer cells.
For example, the breast cancer drug T-DM1 consists of trastuzumab linked to a chemotherapy called DM1. T-DM1 targets the delivery of chemotherapy to HER2-positive cancer cells.
Other antibody-drug conjugates, including the Trop-2 antibody-drug conjugates, are under study for the treatment of metastatic breast cancers, including metastatic triple negative breast cancers .
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 .
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 are still under study for the treatment of metastatic breast cancer.
Bevacizumab remains FDA-approved for use in other cancers.
Some drugs are made from biological products (biologics) such as antibodies or proteins. Trastuzumab and pertuzumab (Perjeta) are breast cancer treatment drugs made from biologics (they are made from antibodies).
A biosimilar drug is a “generic like” version of a drug that contains biologics. Usually, the biosimilar protein has the exact same structure as the original biologic.
The name of a biosimilar drug includes the name of the original biologic drug. For example, trastuzumab-dkst is a biosimilar form of the drug trastuzumab.
A biosimilar drug may cost less than the original drug.
To be approved by the U.S. Food and Drug Administration (FDA), the biosimilar drug must work the same way as the original drug and it must have the same :
The side effects of the biosimilar drug cannot be different from those of the original drug. Also, the biosimilar drug must be the same form as the original drug. For example, if the original drug is given by vein (through an IV) the biosimilar drug must also be given by vein.
At this time, there are 4 FDA-approved biosimilar drugs for breast cancer treatment. They are all biosimilar forms of trastuzumab and can be used to treat early and metastatic HER2-positive breast cancers:
Other biosimilar drugs for breast cancer are under study.
Some drugs used to treat side effects of chemotherapy and other breast cancer treatments have biosimilar forms.
For example, some people get a white blood cell growth factor drug, such as filgrastim (Neupogen) or pegfilgrastim (Neulasta), to help maintain their blood counts during chemotherapy. Tbo-filgrastim (Granix) and pegfilgrastim-jmdb (Fulphila) are the biosimilar forms of these drugs.
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, some breast cancers may benefit from them.
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 programmed cell death protein 1 (PD-1). Pembrolizumab may help take the brakes off the PD-1 to allow the body to kill more cancer cells .
Other immunotherapy drugs are under study.
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.
The Expanded Access (EA) 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.
EA, also known as “compassionate use,” gives patients that have exhausted their treatment options and are not eligible for (or able to participate in) a clinical trial, access to investigational drugs before they have been approved by the FDA.
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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