Many new treatments for metastatic breast cancer are under study.
Most of these are drug therapies. Some focus on treating the whole body, while others focus on the breast, chest wall and nearby lymph nodes.
Findings from clinical trials will determine whether or not these treatments will become a part of the standard of 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 new web-based personalized clinical trial matching tool- the Metastatic Trial Search.
Tyrosine kinase inhibitors
Tyrosine kinase inhibitors are targeted therapies for cancer.
Some tyrosine kinase inhibitors are used to treat other types of cancer. Lapatinib (Tykerb) is the only tyrosine kinase inhibitor FDA-approved for breast cancer treatment. It’s only used to treat HER2-positive metastatic breast cancer.
Other tyrosine kinase inhibitors, including neratinib, are under study for use in metastatic breast cancer treatment.
PARP inhibitors
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.
Today, PARP inhibitors are only offered in clinical trials for people with metastatic breast cancer.
Early findings suggest PARP inhibitors hold the most promise for people with metastatic breast cancer who have a BRCA1 or BRCA2 gene mutation [40].
Olaparib
The PARP inhibitor olaparib is under study for treatment of HER2-negative metastatic breast cancer in women with a BRCA1 or BRCA2 gene mutation. A randomized clinical trial found olaparib gave these women more time before the cancer spread compared to chemotherapy [66].
Although olaparib is used to treat some other types of cancer, it’s not FDA-approved for breast cancer treatment at this time.
Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors
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.
Palbociclib (Ibrance) and ribociclib (Kisqali) are the only 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.
Abemaciclib
The CDK4/6 inhibitor abemaciclib is under study for the treatment of hormone receptor-positive, HER2-negative metastatic breast cancers that are currently being treated with hormone therapy (or have been treated with hormone therapy in the past).
A randomized clinical trial found abemaciclib in combination with the hormone therapy drug fulvestrant gave women with hormone receptor-positive, HER2-negative metastatic breast cancer more time before the cancer spread compared to fulvestrant alone [67].
Other CDK4/6 inhibitors are under study for use in metastatic breast cancer treatment.
PI3 kinase inhibitors
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 the treatment of metastatic breast cancer.
Bevacizumab (Avastin) and other anti-angiogenesis drugs
Anti-angiogenesis drugs, such as bevacizumab (Avastin), block the growth of new blood vessels (angiogenesis). Without a blood supply, the cancer cannot grow.
Although early data showed bevacizumab 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 [41].
However, bevacizumab and other anti-angiogenesis are still under study for the treatment of metastatic breast cancer.
Bevacizumab remains FDA-approved for use in other cancers.
Biosimilar drugs
Some drugs contain biological products such as antibodies. A biosimilar drug is very similar to a brand name drug that contains biological products.
To be approved by the U.S. Food and Drug Administration (FDA), the biosimilar drug must work the same way as the brand name drug and it must have the same [42]:
- Dose and strength
- Safety and effectiveness when used alone or in combination with other treatments
Biosimilar drugs usually cost less than brand name drugs.
Some biosimilar drugs for breast cancer are under study. However, today, none are FDA-approved.
Biosimilar for trastuzumab (Herceptin)
A large study found a biosimilar form of trastuzumab is as safe and effective as trastuzumab in the treatment of HER2-positive metastatic breast cancer [43].
However, this biosimilar form of trastuzumab is not yet FDA-approved.
Immunotherapy
Drugs that help the body’s immune system attack cancer cells are now used to treat many cancers (including melanoma and lung cancer).
Immunotherapy drugs “take the brakes off” the natural factors that limit how the immune system can control tumor cells. For this reason, they are sometimes called “checkpoint inhibitors.”
Many types of immunotherapy drugs are under study. Clinical trials are studying whether they may play a role in metastatic breast cancer treatment [44].
Pembrolizumab
The immunotherapy drug pembrolizumab is under study for the treatment of triple negative metastatic breast cancer [45].
Some triple negative cancer cells have a receptor that limits 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 [45].
Other immunotherapy drugs are under study.
Methods of checking treatment response
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 cells and circulating tumor DNA (liquid biopsies)
Circulating tumor cell levels can help predict survival for people with metastatic breast cancer [46-47].
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 in metastatic cancers [48-49].
At this time, circulating tumor cell and circulating tumor DNA tests (sometimes called liquid biopsies) should not be used to guide treatment because they have not been shown to offer benefit [50-52].
However, these topics are under study.
Clinical trials
After talking with your health care provider, we encourage you to consider joining a clinical trial of new treatments 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 new 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.
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 $920M to researchers in 48 states and 21 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. |
*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.