Immunotherapy for Metastatic Breast Cancer

What are immunotherapy drugs?

Immunotherapy drugs help the body’s immune system attack cancer cells.

There are many types of immunotherapy drugs. Certain immunotherapy drugs may be helpful in treating some metastatic breast cancers.

Researchers are studying how to identify the metastatic breast cancers that will respond best to immunotherapy.

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) is a checkpoint inhibitor immunotherapy antibody drug used to treat some metastatic breast cancers.

Other immunotherapy drugs to treat metastatic breast cancer are under study.

Pembrolizumab (Keytruda) and treatment for triple negative metastatic breast cancer

Triple negative breast cancers are:

Pembrolizumab in combination with chemotherapy is FDA-approved as a first treatment for metastatic triple negative breast cancers that are programmed cell death ligand 1-positive (PD-L1-positive). All metastatic triple negative breast cancers are tested to learn if they are PD-L1-positive and pembrolizumab would be helpful as a first treatment [4].

Compared to chemotherapy alone, chemotherapy in combination with pembrolizumab may give people with metastatic PD-L1-positive triple negative breast cancer more time before the cancer worsens and may improve survival [58-59].

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For a summary of research studies on pembrolizumab and triple negative metastatic breast cancer treatment, visit the Breast Cancer Research Studies section.

Learn more about triple negative breast cancer.

Learn more about treatment for metastatic breast cancer.

Learn about emerging areas in treatment for metastatic breast cancer.

Learn about pembrolizumab and treatment for early triple negative breast cancer.

Pembrolizumab (Keytruda) and treatment for metastatic breast cancers with a high tumor burden

Pembrolizumab is a checkpoint inhibitor immunotherapy drug used to treat metastatic breast cancers that have a high tumor mutational burden. A high tumor mutational burden means there are a high number of gene mutations in the metastatic breast cancer cells.

It’s not common for metastatic breast cancers to have a high tumor mutational burden. However, high tumor burden is more common in triple negative metastatic breast cancers than in estrogen receptor-positive or HER2-positive metastatic breast cancers.

Learn more about triple negative breast cancer.

Learn more about treatment for metastatic breast cancer.

Learn about emerging areas in treatment for metastatic breast cancer.

How is pembrolizumab given?

Pembrolizumab is given by vein (through an IV).

Side effects of pembrolizumab

Side Effects

Pembrolizumab

Possible side effects include fatigue, muscle pain, decreased appetite, itchiness, diarrhea, nausea, rash and constipation.

Pembrolizumab can cause colitis (inflammation of the intestines), liver problems and hormone gland problems.

In rare cases, it 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 sources [60].

Some of these side effects may be permanent.

Before you begin treatment with pembrolizumab, talk with your health care provider about possible side effects and how to manage them.

Atezolizumab (Tecentriq)

The checkpoint inhibitor immunotherapy drug atezolizumab was given accelerated FDA approval in 2019. However, the manufacturer withdrew its application for full FDA approval in August 2021.

If you’ve been taking atezolizumab for metastatic breast cancer, talk with your health care provider about your treatment options.

Atezolizumab remains FDA-approved for use in other cancers.

Monitoring metastatic breast cancer

You’ll be monitored (checked) regularly with scans to see if the cancer is responding to treatment. If it’s no longer working, or if the side effects are not manageable, your health care provider will change your treatment or discuss other options.

Learn more about how metastatic breast cancer is monitored.

Clinical trials

Clinical trials offer the chance to try new treatments and possibly benefit from them.

Many clinical trials are available. Some are for the first treatment a person might get for their metastatic breast cancer, and others are for treatments later in the disease course. Consider joining a clinical trial when you’re newly diagnosed, when your oncologist is considering changing treatments or when there are limited treatment options.

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.

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Metastatic Trial Search

The Metastatic Trial Search is a web-based clinical trial matching tool that can help you find clinical trials that fit your needs.

Learn more about clinical trials for people with metastatic breast cancer.

Learn what Komen is doing to help people find and participate in breast cancer clinical trials, including trials supported by Komen.

Financial assistance

Costs related to metastatic breast cancer care can quickly become a financial burden. Dealing with finances and insurance can be overwhelming.

Many cancer centers have patient 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.

Funding is available for eligible individuals undergoing breast cancer treatment at any stage or living with metastatic breast cancer (stage 4).

To learn more about this program and other helpful resources, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636) or email helpline@komen.org.

Se habla español.

SUSAN G. KOMEN® METASTATIC BREAST CANCER SUPPORT RESOURCES

  • Do you need help with a metastatic breast cancer diagnosis? We’re here for you. The Komen Patient Care Center is your trusted, go-to source for timely, accurate breast health and breast cancer information, services and resources. Our navigators offer free, personalized support to patients, caregivers and family members, including education, emotional support, financial assistance, help accessing care and more. Get connected to a Komen navigator by contacting the Breast Care Helpline at 1-877-465-6636 or email helpline@komen.org to get started. All calls are answered Monday through Thursday, 9 a.m to 7 p.m. ET and Friday, 9 a.m. to 6 p.m. ET. Se habla español.
  • We offer an online support community through our closed Komen Metastatic Breast Cancer (Stage IV) Group. The Facebook group provides a place where those living with metastatic breast cancer, and those who love them, can find support, friendship and information. Click the link above or visit Facebook and search for Komen Metastatic Breast Cancer (Stage IV) Group and request to join.
  • Our free MBC Impact Series provides people living with metastatic breast cancer and their loved ones a safe, collaborative space to gather information related to metastatic breast cancer and discover practical resources to help make decisions for improved physical and emotional health. To learn more and register visit www.komen.org/mbcseries.
  • Our Real Pink podcast series covers many relevant topics for people living with metastatic breast cancer and caregivers.
  • Our fact sheets, booklets and other education materials offer additional information.

Updated 12/28/23

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