HER2-Targeted Therapies for Early Breast Cancer
This section discusses HER2-targeted therapies for early and locally advanced breast cancer.
Learn about HER2-targeted therapies for metastatic breast cancer (also called stage IV or advanced breast cancer).
HER2-targeted therapies and HER2-positive breast cancer
HER2-positive breast cancers have a lot of the protein called HER2 on the surface of their cells. The HER2 protein is an important driver of cell growth and survival.
HER2-targeted therapies are designed to treat HER2-positive breast cancers. They have no role in the treatment of HER2-negative cancers.
Testing for HER2 status
The HER2 status of a tumor is determined by testing tissue removed during a biopsy. All newly diagnosed breast cancers are tested for HER2 status.
About 10% to 20% of newly diagnosed breast cancers are HER2-positive [155-156]. These breast cancers can be treated with HER2-targeted therapies.
Trastuzumab (Herceptin)
How does trastuzumab work?
Trastuzumab is an antibody drug specially made to target HER2-positive cancer cells.
Trastuzumab attaches to the HER2 protein on the surface of HER2-positive breast cancer cells. This can slow or stop their growth.
Breast cancer treatment
For people with HER2-positive early breast cancer, chemotherapy plus trastuzumab cuts the risk of recurrence (a return of breast cancer) in half compared to chemotherapy alone [157-159].
Trastuzumab is given through an IV into a vein or by an injection under the skin every 3 weeks for one year.
Treatment with trastuzumab may begin before breast cancer surgery (neoadjuvant therapy) or after surgery (adjuvant therapy).
Trastuzumab is also used to treat HER2-positive metastatic breast cancers.
Talk with your health care provider if you have any questions or concerns about your medications.
Learn about neoadjuvant treatment with trastuzumab.
Learn more about treatment for HER2-positive metastatic breast cancers.
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For a summary of research studies on trastuzumab and overall survival in early breast cancer, visit the Breast Cancer Research Studies section. |
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For a summary of research studies on trastuzumab and treatment for metastatic breast cancer, visit the Breast Cancer Research Studies section. |
Side effects of trastuzumab
Before you begin treatment with trastuzumab, talk with your health care team about possible side effects and how to manage them.
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Side Effects |
Trastuzumab |
Possible side effects include headache, fever and chills. Trastuzumab can cause serious heart problems. Your heart will be checked before and during treatment to help make sure there are no problems. |
Adapted from select sources [11,157,160]. |
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Trastuzumab doesn’t cause hair loss, nausea or vomiting, and has no effect on red blood cell or white blood cell counts.
Learn more about side effects.
Heart problems linked to trastuzumab
Trastuzumab use is linked to congestive heart failure, a serious heart condition.
In clinical trials, about 2% to 3% of those treated with chemotherapy plus trastuzumab had heart failure, compared to fewer than 1% of those treated with chemotherapy alone [157,160].
This risk of heart problems is higher with chemotherapy regimens that include an anthracycline drug compared to regimens without an anthracycline drug [11,157].
The risk of heart problems may also be higher for people over 60 and for those who already have heart problems [11,160].
For most people who develop a heart problem while getting trastuzumab, the condition improves after stopping trastuzumab. For a few, it may be permanent.
Avoiding heart problems
Your heart will be checked before and during treatment with trastuzumab. This is to help make sure there are no problems, or if there are problems, they’re caught early.
Adopting a lifestyle that includes a healthy diet, regular exercise and for those who smoke, quitting smoking is a good way to help avoid heart problems related to treatment.
Biosimilar trastuzumab
A biosimilar drug is a “generic-like” version of a drug that contains biologics (biological products) such as antibodies or proteins. Trastuzumab is a biologic drug.
The FDA-approved biosimilar forms of trastuzumab are safe and effective treatments for early and metastatic HER2-positive breast cancers.
Learn more about biosimilars.
To learn more about trastuzumab, visit the National Institutes of Health’s Medline Plus website.
Ado-trastuzumab emtansine (Kadcyla, T-DM1, trastuzumab emtansine)
How does ado-trastuzumab emtansine work?
Ado-trastuzumab emtansine (Kadcyla, T-DM1, trastuzumab emtansine) is an antibody-drug conjugate.
Ado-trastuzumab emtansine consists of the HER2-targeted antibody drug trastuzumab (Herceptin) and a chemotherapy called DM1 (so it’s sometimes called T-DM1). The combination of drugs allows the targeted delivery of chemotherapy to HER2-positive cancer cells.
Breast cancer treatment
Ado-trastuzumab emtansine is used to treat some people with HER2-positive early breast cancer who have cancer remaining in their breast or lymph nodes after neoadjuvant therapy (given before surgery) [11]. The use of ado-trastuzumab emtansine can reduce the risk of breast cancer recurrence (a return of breast cancer) or breast cancer death by about 40% compared to treatment with trastuzumab [161].
Ado-trastuzumab emtansine is given through an IV into a vein every 3 weeks for 14 cycles. Treatment with ado-trastuzumab emtansine begins after breast surgery.
Ado-trastuzumab emtansine is under study for use in the neoadjuvant setting [162].
Talk with your health care provider if you have any questions or concerns about your medications.
Learn about ado-trastuzumab emtansine and metastatic breast cancer treatment.
Side effects of ado-trastuzumab emtansine
Before you begin treatment with ado-trastuzumab emtansine, talk with your health care team about possible side effects and how to manage them.
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Side Effects |
Ado-trastuzumab emtansine |
Possible side effects include nausea, fatigue, muscle and joint pain, constipation, neuropathy (nerve damage that may cause pain or numbness, usually in the fingers or toes), low platelet counts and headache. Ado-trastuzumab emtansine can also cause liver problems. Your liver will be checked before and during treatment to help make sure there are no problems. Because ado-trastuzumab emtansine contains trastuzumab, it can cause serious heart problems. Learn more about this risk and steps taken to monitor your heart during treatment. |
Adapted from select sources [161,163]. | |
Ado-trastuzumab emtansine doesn’t usually cause hair loss.
Learn more about side effects.
To learn more about ado-trastuzumab emtansine, visit the National Institutes of Health’s Medline Plus website.
Pertuzumab (Perjeta)
How does pertuzumab work?
Pertuzumab is an antibody drug that targets HER2-positive cancer cells, but in a different way than trastuzumab.
Breast cancer treatment
Pertuzumab is used in combination with trastuzumab and chemotherapy to treat some HER2-positive breast cancers [11].
In people with HER2-positive early breast cancers at high risk of recurrence, adding pertuzumab to treatment with trastuzumab and chemotherapy can reduce the risk of recurrence by about 20% [164].
Pertuzumab is always given in combination with trastuzumab. It’s not given on its own. The combination of drugs is given through an IV into a vein or by an injection under the skin every 3 weeks for up to one year.
Treatment with pertuzumab and trastuzumab may begin before breast cancer surgery (neoadjuvant therapy) or after surgery (adjuvant therapy).
Talk with your health care provider if you have any questions or concerns about your medications.
Learn about neoadjuvant treatment with pertuzumab and trastuzumab.
Learn about pertuzumab and metastatic breast cancer treatment.
Side effects of pertuzumab
Before you begin treatment with pertuzumab, talk with your health care team about possible side effects and how to manage them.
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Side Effects |
Pertuzumab |
Possible side effects include diarrhea, nausea, fatigue and rash. Pertuzumab is always given in combination with trastuzumab. Trastuzumab can cause serious heart problems. Learn more about this risk and steps taken to monitor your heart during treatment. |
Adapted from select sources [165]. | |
Learn more about side effects.
To learn more about pertuzumab, visit the National Institutes of Health’s Medline Plus website.
Neratinib (Nerlynx)
How does neratinib work?
Tyrosine-kinase inhibitors, such as neratinib, 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.
Breast cancer treatment
Neratinib is used to treat HER2-positive early breast cancer in some people who have completed treatment with trastuzumab (Herceptin) [11].
Treatment with neratinib may reduce the risk of breast cancer recurrence in some people [166].
Neratinib is a pill taken every day for one year.
Talk with your health care provider if you have any questions or concerns about taking your medications.
Learn about neratinib and the treatment of metastatic breast cancer.
Side effects of neratinib
Before you begin taking neratinib, talk with your health care team about possible side effects and how to manage them.
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Side Effects |
Neratinib |
The most common side effect is diarrhea. Your health care provider will recommend medications to help prevent and control the diarrhea. Other possible side effects include nausea, vomiting, fatigue, abdominal pain and rash. In rare cases, neratinib has been linked to liver problems. Your liver function will be checked throughout your treatment to help make sure there are no problems. |
Adapted from select sources [167]. | |
Learn more about side effects.
To learn more about neratinib, visit the National Institutes of Health’s Medline Plus website.
Treatment guidelines
Although the exact treatment for breast cancer varies from person to person, evidence-based guidelines help make sure high-quality care is given. These guidelines are based on the latest research and agreement among experts.
The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) are respected organizations that regularly review and update their guidelines.
In addition, the National Cancer Institute (NCI) has treatment overviews.
Talk with your health care team about which treatment guidelines they follow.
After you get a recommended treatment plan from your health care team, study your treatment options. Together with your health care team, make thoughtful, informed decisions that are best for you. Each treatment has risks and benefits to consider along with your own values and lifestyle.
Prescription drug assistance
Prescription drug costs can quickly become a financial burden for you and your family.
Medicare and many insurance companies offer prescription drug plans. One may already be included in your policy, or you may be able to buy an extra plan for prescriptions.
Although most HER2-targeted therapies for early breast cancer are given through an IV into a vein or by an injection, neratinib is a pill. So, neratinib is covered under your health insurance plan’s prescription drug benefit rather than the plan’s medical benefit. This means there are usually out-of-pocket costs, which can add up over time.
You may qualify for programs that help with drug costs or offer low-cost or free prescriptions.
Many cancer centers have financial counselors who can discuss insurance and cost coverage with you.
Learn about insurance plans and prescription drug assistance programs.
Learn about other financial assistance programs.
Komen Financial Assistance Program |
Susan G. Komen® created the Komen Financial Assistance Program to help those struggling with the costs of breast cancer treatment by providing financial assistance to eligible individuals. To learn more about this program and other helpful resources, call the Komen Patient Care Center at 1-877 GO KOMEN (1-877-465-6636) or email helpline@komen.org. Se habla español. |
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Susan G. Komen®‘s position on fairness in oral cancer drug coverage |
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Insurance coverage of oral cancer drugs Cancer medications given through an IV into a vein or by an injection (under the skin or into a muscle) are usually covered under a health insurance plan’s medical benefit. However, oral cancer drugs (cancer medications that are pills) are usually covered under a health insurance plan’s prescription drug benefit. As a result, people often find themselves facing high out-of-pocket costs when filling prescriptions for oral cancer drugs. Sometimes these costs can be thousands of dollars a month. The impact of high cost-sharing High prescription drug costs and the resulting out-of-pocket burden on patients are a barrier to care. They can prevent people from getting the medications prescribed by their health care providers. No one should be forced to get less appropriate treatment because an insurer gives more coverage for IV and injectable drugs than for pills. Efforts to increase fairness in drug coverage Komen supports state and federal efforts to require insurers to provide the same or better coverage for oral cancer drugs as they do for IV and injectable cancer drugs. This would help make sure patients have access to affordable, appropriate treatment. Become a Komen Advocacy Insider Sign up to be a Komen Advocacy Insider and get informed when action is needed on oral drug coverage parity at the state or national level. |
Clinical trials
Research is ongoing to improve all areas of treatment for breast cancer.
New therapies are being studied in clinical trials. The results of these studies will decide whether these 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 right for you.
Susan G. Komen® Patient Care Center |
If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email clinicaltrialinfo@komen.org. Se habla español. |
BreastCancerTrials.org in collaboration with Komen offers a custom matching service to help find clinical trials that fit your needs.
Learn what Komen is doing to help people find and participate in breast cancer clinical trials, including trials supported by Komen.
Learn more about clinical trials.
Susan G. Komen® Support Resources |
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*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.
Updated 03/03/25
This content is regularly reviewed by an expert panel including researchers, practicing clinicians and patient advocates.
