Immunotherapy
What are immunotherapy drugs?
Immunotherapy drugs help your body’s immune system attack cancer cells. There are many types of immunotherapy drugs.
Certain immunotherapy drugs are helpful in treating some breast cancers.
Learn about immunotherapy and metastatic breast cancer treatment.
Checkpoint inhibitors
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 cancer cells.
Pembrolizumab (Keytruda) and early breast cancer
Pembrolizumab (Keytruda) is a checkpoint inhibitor immunotherapy drug. Pembrolizumab is FDA-approved for the treatment of early triple negative breast cancer (TNBC) at high risk of recurrence (a return of breast cancer).
TNBC is:
- Estrogen receptor-negative (ER-negative)
- Progesterone receptor-negative (PR-negative)
- HER2-negative
Pembrolizumab is given for up to one year. You get the first 6 months of pembrolizumab before breast surgery (called neoadjuvant or preoperative therapy). The second half is given after breast surgery (adjuvant therapy).
Studies show adding neoadjuvant pembrolizumab to neoadjuvant chemotherapy may lower the risk of breast cancer recurrence and improve survival in people with early TNBC [173-175].
If you’ve been diagnosed with early TNBC, talk with your health care provider about whether pembrolizumab is an option for you.
Other checkpoint inhibitor immunotherapy drugs are under study for use in early breast cancer treatment.
Learn more about triple negative breast cancer.
Learn more about neoadjuvant therapy.
| For a summary of research studies on pembrolizumab and early breast cancer treatment, visit the Breast Cancer Research Studies section. |
How is pembrolizumab given?
Pembrolizumab is given through an IV into a vein every 3 weeks or every 6 weeks for up to one year. You either get a smaller dose once every 3 weeks, or you get a larger dose once every 6 weeks.
You’ll get some pembrolizumab before surgery and some after surgery.
Pembrolizumab can be given on the same day as chemotherapy.
Talk with your health care provider if you have any questions or concerns about your medications.
Side effects of pembrolizumab
Before you begin treatment with pembrolizumab, talk with your health care team about possible side effects and how to manage them.
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Side Effects |
Pembrolizumab |
Possible side effects include fatigue, muscle pain, decreased appetite, itchiness, diarrhea, nausea, rash and constipation. Pembrolizumab can cause thyroid problems and other hormone problems, which may be permanent and lead to the need for hormone treatment. Pembrolizumab can also cause severe colitis and liver problems that sometimes can lead to hospitalization. In rare cases, pembrolizumab can cause lung inflammation, which can lead to death. Tell your health care provider right away if you have shortness of breath or other breathing problems while taking this drug. |
Adapted from select source [176]. |
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Learn more about side effects.
Pembrolizumab and metastatic breast cancer treatment
Pembrolizumab is FDA-approved for the treatment of some metastatic breast cancers.
Learn more about pembrolizumab and metastatic breast cancer treatment.
Under study
Vaccines
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.
Learn about clinical trials.
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 benefits and risks to consider along with your own values and lifestyle.
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 determine whether these therapies become part of the standard of care. Clinical trials can also study other parts of care, such as ways to manage side effects.
After discussing the benefits and risks with your oncologist, we encourage you to consider joining a clinical trial if there’s one right for you.
Read our blog, Four Things to Know About Clinical Trials When You’re Diagnosed with Breast Cancer.
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 how Komen-funded research is improving treatment for breast cancer.
Learn more about clinical trials.
Financial assistance
Costs related to breast cancer treatment can quickly become a financial burden. Dealing with finances and insurance can be overwhelming.
Many hospitals have financial counselors who can discuss insurance and cost coverage with you. They may be able to arrange a payment plan for hospital-related costs.
You may qualify for financial assistance from federal, state or local programs. A financial counselor or social worker at your hospital can help you learn about these programs.
Learn more about insurance plans and prescription drug assistance programs.
Learn more 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. Learn about other financial assistance programs. |
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 03/21/26
This content is regularly reviewed by an expert panel including researchers, practicing clinicians and patient advocates.
