Emerging Areas in Drug Therapies for Early Breast Cancer
This is a promising time in breast cancer research.
New drug therapies for early breast cancer, as well as some tools for tailoring treatment, are under study in clinical trials. The results of these studies will decide whether these new, emerging therapies become part of the standard of care.
After discussing the benefits and risks with your health care provider, we encourage you to consider joining a clinical trial if there’s one that’s right for you.
This section discusses emerging areas of research in the treatment of early breast cancer.
Learn more about clinical trials.
Antibody-drug conjugates are a combination of an antibody therapy and a chemotherapy drug. This combination allows the targeted delivery of chemotherapy to certain cancer cells.
The antibody-drug conjugate ado-trastuzumab emtansine (Kadcyla, T-DM1, trastuzumab emtansine) is FDA-approved for the treatment of early and metastatic HER2-positive breast cancers.
Other antibody-drug conjugates used in treatment for metastatic breast cancer are under study for use in early breast cancer treatment, including trastuzumab deruxtecan (Enhertu) and sacituzumab govitecan (Trodelvy).
Tyrosine-kinase inhibitors are drugs that target tyrosine-kinase enzymes, which are important for cell functions. These drugs can block tyrosine-kinase enzymes at many points along the cancer growth pathway.
The tyrosine-kinase inhibitors tucatinib (Tukysa), lapatinib (Tykerb) neratinib (Nerlynx) are FDA-approved for the treatment of HER2-positive metastatic breast cancer. Neratinib is also FDA-approved for the treatment of early breast cancer.
Tucatinib is under study for use in early breast cancer treatment .
Poly(ADP-ribose) polymerase (PARP) is an enzyme that helps repair DNA damage. PARP inhibitor drugs work by keeping cancer cells from repairing damaged tumor DNA.
The PARP inhibitors olaparib (Lynparza) and talazoparib (Talzenna) are FDA-approved for the treatment of some metastatic breast cancers in people who have a BRCA1, BRCA2 or PALB2 inherited gene mutation. Olaparib is also FDA-approved for the treatment of some early breast cancers.
Talazoparib is under study for early breast cancer treatment [71,156].
Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors
Cyclin-dependent kinase 4 and 6 (CDK4 and CDK6) are enzymes important in cell division. CDK4/6 inhibitors are drugs designed to interrupt the growth of cancer cells.
The CDK4/6 inhibitor drugs abemaciclib (Verzenio), palbociclib (Ibrance) and ribociclib (Kisqali) are FDA-approved to treat some metastatic breast cancers.
Abemaciclib in combination with hormone therapy is FDA-approved for the treatment of certain early breast cancers at high risk of recurrence.
Ribociclib is under study for use in early breast cancer treatment and abemaciclib is under study for the treatment of additional early breast cancers.
Bone density medications
Bisphosphonates and the RANK ligand (RANKL) inhibitor drug denosumab are bone density medications used to help prevent bone loss and treat osteoporosis. They are also used as a bone-strengthening treatment for women with breast cancer that has spread to the bones (bone metastases).
For some people with early breast cancer, bisphosphonates may lower the risk of breast cancer recurrence and may be recommended [8,72-73].
Most studies show denosumab does not lower the risk of breast cancer recurrence in people with early breast cancer [74-75].
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 PIK3CA gene mutation that can affect PI3 kinase and cause the tumor to grow. This mutation is in the genes of the tumor, not the person.
PI3 kinase inhibitors are drugs designed to interrupt PI3 kinase signals and stop the growth of cancer cells with PIK3CA gene mutations.
The PI3 kinase inhibitor alpelisib (Piqray) is FDA-approved for the treatment of some metastatic breast cancers that have a PIK3CA gene mutation.
The PI3 kinase inhibitor taselisib in combination with the hormone therapy drug letrozole is under study for early breast cancer treatment .
Immunotherapy drugs help your body’s immune system attack cancer cells.
Checkpoint inhibitors are the most widely used type of immunotherapy drugs. These drugs “take the brakes off” the natural factors that limit how the immune system can control tumor cells.
The checkpoint inhibitor immunotherapy drug pembrolizumab (Keytruda) is FDA-approved for the treatment of some early breast cancers and some metastatic breast cancers.
Other immunotherapy drugs, such as durvalumab, are under study for use in the treatment of early breast cancer .
Vaccines are a type of immunotherapy. Like vaccines that protect against the flu or measles, cancer vaccines are designed to build up the body’s immunity against disease.
Breast cancer vaccines are still in the early stages of development.
Circulating tumor cells and circulating tumor DNA (liquid biopsies) and prognosis
Circulating tumor cell levels and circulating tumor DNA may help predict recurrence and survival in people with early breast cancer [78-82].
Some studies have found women with early breast cancer who had more circulating tumor cells had a worse prognosis (worse breast cancer outcomes) than those who had few or no circulating tumor cells [78-80].
Similarly, some findings have shown women with early breast cancer who have circulating tumor DNA after neoadjuvant therapy (given before surgery) or adjuvant therapy (given after surgery) may have a worse prognosis than those with no circulating tumor DNA [81-82].
Circulating tumor cell and circulating tumor DNA tests (sometimes called liquid biopsies) are not standard tests at this time and are not used to guide breast cancer treatment. These topics are under study.
Molecular classifications of breast cancer
Molecular and genetic differences in breast cancers may be useful in guiding the development of new drug therapies.
Most studies divide breast cancer into 4 major molecular classifications:
- Luminal A
- Luminal B
- Basal-like/triple negative
Although mainly used in research settings, these classifications may be useful in tailoring treatment in the future.
Learn more about molecular classifications of breast cancer.
Tumor profiling (using gene expression profiling tools) gives information about the genes in cancer cells. Tumor profiling tests look at a set of genes in a sample of the tumor removed during a biopsy or surgery.
The gene profiles of some tumors may help predict whether or not the cancer is likely to metastasize (spread to other parts of the body) . Sometimes, this information can be used to guide breast cancer treatment.
Oncotype DX® and MammaPrint® are tumor profiling tests recommended by the American Society of Clinical Oncology (ASCO) . These tests may be used to help guide the use of chemotherapy for some people with breast cancer.
Tumor profiling may also be called genomic testing, molecular profiling or genetic signatures.
Breast Cancer Index
Breast Cancer Index® is a tumor profiling test that looks at a set of 11 genes to help predict how likely some breast cancers are to metastasize.
Breast Cancer Index may be considered in making treatment decisions about the use of hormone therapy for more than 5 years for some estrogen receptor-positive, HER2-negative, lymph node-negative breast cancers [8,86].
Other tumor profiling tests are under study.
Tamoxifen and anti-depressant use
Some SSRIs, including fluoxetine (Prozac), paroxetine (Paxil) and sertraline (Zoloft), may interfere with tamoxifen. However, it’s not known whether they might impact the effectiveness of tamoxifen. This topic is under study. Results to date are mixed.
If you’re taking an SSRI to treat depression or menopausal symptoms, talk with your health care provider about possible drug interactions and other treatment options.
CYP2D6 and tamoxifen
CYP2D6 is an enzyme that affects how the body metabolizes (breaks down and uses) certain medications.
Large studies found no difference in the risk of breast cancer recurrence in women with genes related to low CYP2D6 function compared to risk in women with genes related to normal or high CYP2D6 function [84-85].
There is no role for routine testing of CYP2D6 in women taking tamoxifen .
After talking with your health care provider, we encourage you to consider joining a clinical trial if there’s one that’s right for you.
Susan G. Komen® Breast Care Helpline
The helpline offers breast cancer clinical trial education and support, such as:
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BreastCancerTrials.org in collaboration with Komen offers a custom matching service to help find clinical trials that fit your needs.
Learn more about clinical trials and find a list of resources to help you find a clinical trial.
Read our perspective on clinical trials.*
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.
To date, Komen has provided nearly $1.1 billion to researchers in 47 states, the District of Columbia and 24 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.