Using the Immune System to Treat Breast Cancer with Immunotherapy

6 min read

Using the Immune System to Treat Breast Cancer with Immunotherapy

Within the body is a complex structure of systems that all work together to keep it in balance. Out of these systems, the immune system is one of the most complex. Made up of various organs, cells, tissues, and proteins (antibodies), the immune system plays a vital role in protecting you from disease and infection. Sometimes, however, the immune system isn’t quite strong enough to fight off certain illnesses, such as breast cancer. 

To give your immune system the boost it needs to fight breast cancer, your oncologist might recommend immunotherapy treatment. These drugs make it easier for your body to identify and fight breast cancer cells while leaving healthy cells intact.

Immunotherapy may not be recommended for all breast cancer patients, however, it’s found to be effective for triple-negative breast cancer, which does not respond to hormone therapies, as well as metastatic breast cancer (stage IV).

How Immunotherapy Works in Treating Breast Cancer

The primary role of your immune system is to protect your body from unhealthy invaders, such as viruses, allergens, and abnormal cells, without causing damage to normal cells. To do this, it uses proteins, often called checkpoints, on immune cells that need to be turned on (or off) to start an immune response. When the immune system is functioning properly, this response will be activated once it recognizes something in the body as “foreign” or harmful. 

Unfortunately, it’s not as straightforward when it comes to breast cancer cells. Cancer cells, in general, are more difficult for the body to identify as something that should be eliminated. This is because cancer begins in normal, healthy cells that can eventually become changed or altered. The checkpoints that are usually used to identify a harmful cell are not turned on for cancer cells. 

Because of this, the cancer cells evade the immune system’s natural defenses. This means they are slipping past the immune checkpoints and there is no signal to your body to activate your cancer-killing cells. Therefore, while your immune system may prevent or slow the growth of many cancer cells, it won’t necessarily catch them all.

Immunotherapy is a type of biological therapy that may be used for some types of breast cancer. It uses specific medications that can help train your immune system to recognize and attack breast cancer cells more effectively. It does this by working on specific proteins involved in the immune system to enhance the immune response when it comes to attacking cancer cells. Immunotherapy may be used by itself or in combination with other breast cancer treatments like chemotherapy or radiation therapy.

Breast Cancer Immunotherapy


Immune Checkpoint Inhibitors for Breast Cancer

While there are several types of immunotherapies, immune checkpoint inhibitors (also called PD-1/PD-L1 pathway inhibitors) are the common type used for the treatment of breast cancer. Immune checkpoint inhibitor drugs block immune checkpoints, allowing immune cells to see the cancer cells as “bad” and respond appropriately by attacking the breast cancer cells.

The Food and Drug Administration (FDA) has approved Keytruda (pembrolizumab), a checkpoint inhibitor drug, to treat breast cancer. This drug targets PD-1 and PD-L1 — proteins on immune system T cells that normally help keep them from attacking other cells in the body. When these specific proteins are blocked, these drugs boost the immune response against breast cancer cells. 

Keytruda is often given in combination with chemotherapy to treat high-risk, early-stage, triple-negative breast cancer (TNBC). It may be given: 

  • To treat Stage II or Stage III breast cancers before or after surgery
  • To treat breast cancer that has recurred locally and can’t be surgically removed
  • To treat metastatic breast cancer (cancer that has spread to other parts of the body)

Your RMCC breast cancer specialist can help determine if immunotherapy is right for you. To ensure that your breast cancer is more likely to respond to treatment with Keytruda, your oncologist might suggest testing your cancer cells for the PD-L1 protein. Speak to your oncologist about any questions you may have about your treatment plan.

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Possible Side Effects Associated With Breast Cancer Immunotherapy Treatment

As with other cancer treatments, immune checkpoint inhibitors can cause side effects that could affect breast cancer patients in different ways. Side effects you may experience and how they make you feel will depend on various factors including how advanced your breast cancer is, your personal health prior to treatment, and the dose of the immune checkpoint inhibitor drug you are receiving. 

While there is no definite way to know when and if side effects will occur or how serious they will be, it’s important to know what signs to look for. Common side effects associated with breast cancer immunotherapy treatment can include: 

  • Fatigue
  • Nausea
  • Skin rash
  • Cough
  • Poor appetite
  • Diarrhea
  • Constipation 

Other more serious, yet rare side effects include: 

  • Infusion reactions, which often resemble an allergic reaction. Patients might experience side effects, such as fever, chills, rash, dizziness, and difficulty breathing.
  • Autoimmune reactions, which is when the immune system starts to attack other parts of the body. This could result in serious or even life-threatening problems in the lungs, kidneys, liver, intestines, and other organs. 

Your breast cancer specialist can talk with you about possible side effects of the immunotherapy recommended for you and how to watch for and manage them. Any new side effects should be brought to the attention of your breast cancer care team immediately. If the side effects are serious, you may need to stop treatment or take medication designed to suppress your immune system. 

What to Expect During Immunotherapy Treatment 

Immunotherapy for breast cancer is given by intravenous (IV) infusion. In most cases, the drugs are administered every few weeks. It may also be given in combination with other treatments such as chemotherapy.

The timing of your treatment is determined by the dosage you are receiving. Your breast cancer specialist will conduct various tests to determine whether the treatment is working. 

Immunotherapy is normally delivered at each of our clinics, at the same location as your oncologist and the rest of the breast cancer care team. This allows you to get treated in a way that’s convenient for you. Find a breast cancer specialist near you.

Breast Cancer Immunotherapy Treatment in Colorado

If you or someone you know has been diagnosed with breast cancer, request an appointment to meet with one of our breast cancer specialists located in Denver, Colorado Springs, Boulder, and other areas throughout the Colorado Front Range. We also offer second opinions for anyone who needs more information to help decide which cancer treatment recommendations will work best for them.

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Find a Breast Cancer Specialist

M. Andrew Monticelli, MD

Medical Oncologist / Hematologist

Colorado Springs, CO

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Praveena Solipuram, MD

Medical Oncologist / Hematologist

Thornton, CO

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Kelly Casteel, MD

Medical Oncologist / Hematologist

Longmont, CO

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Charles Leonard, MD

Radiation Oncologist

Littleton, CO

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Gregory Britt, MD

Medical Oncologist / Hematologist

Boulder, CO

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