Immunotherapy for Breast Cancer

Immunotherapy is the use of medicines to stimulate a person’s own immune system to recognize and destroy cancer cells more effectively. Immunotherapy can be used to treat some types of breast cancer.

Immune checkpoint inhibitors

An important part of the immune system is its ability to keep itself from attacking normal cells in the body. To do this, it uses “checkpoints” – proteins on immune cells that need to be turned on (or off) to start an immune response. Breast cancer cells sometimes use these checkpoints to avoid being attacked by the immune system. Drugs that target these checkpoints, known as immunotherapy drugs, help to restore the immune response against the breast cancer cells.

PD-L1 inhibitors

Atezolizumab (Tecentriq) targets PD-L1, a protein that is found on some tumor cells and immune cells. Blocking this protein can help boost the immune response against breast cancer cells. This can shrink some tumors or slow their growth.

Atezolizumab can be used with Abraxane (albumin-bound paclitaxel) for advanced triple-negative breast cancer when the tumor makes the PD-L1 protein. It can be used as part of the first treatment in some people.

Atezolizumab is given as an intravenous (IV) infusion every 2 weeks.

Possible side effects of PD-L1 inhibitors

Side effects of atezolizumab can include fatigue, cough, nausea, loss of appetite, constipation, and diarrhea.

Other, more serious side effects occur less often. Immunotherapy drugs work by basically removing the brakes on the body’s immune system. Sometimes the immune system starts attacking other parts of the body, which can cause serious or even life-threatening problems in the lungs, intestines, liver, hormone-making glands, kidneys, or other organs.

It’s very important to report any new side effects to your health care team quickly. If serious side effects do occur, treatment may need to be stopped and you may get high doses of corticosteroids to suppress your immune system.


More information about immunotherapy

To learn more about how drugs that work on the immune system are used to treat cancer, see Cancer Immunotherapy.

To learn about some of the side effects listed here and how to manage them, see Managing Cancer-related Side Effects.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Jagsi R, King TA, Lehman C, Morrow M, Harris JR, Burstein HJ. Chapter 79: Malignant Tumors of the Breast. In: DeVita VT, Lawrence TS, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2019.

National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Breast Cancer. Version 2.2019. Accessed at on July 22, 2019.

Schmidt P, Adams S, Rugo HS, Scheeweiss A, Barrios CH, Iwata H, et al. Atezolizumab and Nab-Paclitaxel in Advanced Triple-Negative Breast Cancer. N Engl J Med. 2018 Nov 29;379(22):2108-2121. doi: 10.1056/NEJMoa1809615. Epub 2018 Oct 20.

Last Medical Review: September 18, 2019 Last Revised: September 18, 2019

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