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Immunotherapy is a breakthrough cancer treatment that is transforming the oncology landscape and helping many patients achieve a better outcome and quality of life. While traditional treatments such as surgery, radiation therapy and chemotherapy continue to be more frequently used for breast cancer treatment, immunotherapy is showing great promise among certain patients.

What is breast cancer immunotherapy?

Immunotherapy is designed to capitalize on the infection-fighting power of the body's own immune system by enhancing its natural ability to defend the body against viruses, bacteria and other potentially harmful invaders, including cancer. Specifically, immunotherapy aims to “train” the immune system to recognize, target and destroy certain cancer cells.

In March 2019, the U.S. Food and Drug Administration (FDA) approved pembrolizumab as the first immunotherapy treatment for breast cancer. Pembrolizumab is an immune checkpoint inhibitor, the most common type of immunotherapy. Immune checkpoints are proteins in the body that help the immune system determine the difference between normal cells and foreign invaders. Some cancer cells use immune checkpoint proteins as a “shield” to avoid being identified and attacked by the immune system. Immune checkpoint inhibitors aim to counteract that.

When might a physician suggest immunotherapy for breast cancer?

A physician might suggest a combination of pembrolizumab and chemotherapy for a patient who has early-stage triple-negative breast cancer, a relatively uncommon malignancy that often spreads faster—and tends to be more difficult to treat—than non-triple negative breast cancers.

More specifically, immunotherapy may be an option for a patient who has triple-negative breast cancer that is:

  • Locally advanced (has spread beyond the breast) and cannot be removed with surgery
  • Metastatic (has spread to other parts of the body, such as the bones or liver)
  • In an early stage with a high risk of recurrence

What is the success rate of immunotherapy for breast cancer?

Clinical studies show that the combined approach of immunotherapy and chemotherapy can be effective in certain patients who test positive for PD-L1, a protein found on the surface of some cancer cells or immune cells in a tumor. PD-L1 binds with PD-1, a partner protein found on the surface of certain immune cells (T cells). This bond effectively “switches off” the T cell, allowing the cancer cell to evade detection. Immune checkpoint inhibitors like pembrolizumab work by “releasing the brakes” on the T cells, increasing the likelihood that the T cells will recognize, attack and destroy the cancer cells.

At this point, immunotherapy is not an option for all patients with triple-negative breast cancer. If the PD-L1 protein is not detected on the cancer cells or the immune cells in the tumor, a PD-1 immune checkpoint inhibitor will not be effective for treating the cancer.

What is the dendritic cell vaccine?

Dendritic cell therapy is one of several options for boosting the immune system. Moffitt researchers have seen positive results in clinical trials with a dendritic cell vaccine, which is a cross between a vaccine and a cell therapy. Researchers have discovered that when given peptides or portions of tumor antigens, dendritic cell vaccines prompt the development of natural immunityThese cells act like factories and make other little molecules that activate other parts of the patient's immune system.

As of January 2023, Moffitt has three open clinical trials for dendritic cell therapy in neoadjuvant triple negative and HER2 breast cancer.

Moffitt believes that the use of novel immunotherapies discovered through clinical trials may allow our doctors to treat breast cancer more effectively. These advancements potentially reduce or eliminate the need for chemotherapy, surgery and radiation.

What are the side effects of immunotherapy for breast cancer?

Immunotherapy stimulates a heightened immune system response. As a result, some healthy cells may be targeted and destroyed along with the cancer cells. This can increase inflammation throughout the body, which can cause side effects such as:

  • Skin rashes, blisters or itching
  • Fever and chills
  • Coughing
  • Loss of appetite
  • Nausea
  • Vomiting
  • Diarrhea
  • Constipation
  • Fatigue
  • Headache
  • Anemia

Additional immunotherapy side effects can occur depending on the specific organs and tissues affected by the inflammation. For instance, if the thyroid gland is affected, hypothyroidism (low hormone production by the thyroid) may develop. As a result, the patient may need thyroid hormone replacement in the future.

Because immunotherapy can worsen the symptoms of certain chronic conditions such as lupus or rheumatoid arthritis, this treatment approach is generally not recommended for patients who have an autoimmune disorder.

What is the difference between immunotherapy and chemotherapy?

Immunotherapy and chemotherapy both fight cancer, but each uses a different approach. Immunotherapy drugs are designed to train the immune system to seek out and destroy cancer cells, and then continue to do so over time. Chemotherapy drugs are designed to have a more immediate impact; they work to destroy cancer cells while they are being administered and remain in the body for a short time afterward.

Breast cancer immunotherapy at Moffitt Cancer Center

If you have been diagnosed with breast cancer, you will want to fully explore all of your treatment options so you can feel confident about your choices. In the renowned Don & Erika Wallace Comprehensive Breast Program at Moffitt Cancer Center, you can benefit from the combined expertise of physicians from multiple specialties, all of whom focus their practice exclusively on breast cancer. In one location, we offer a full range of the latest diagnostic and treatment services, including immunotherapy.

The dedicated research team at Moffitt is actively exploring the potential of immunotherapy for patients with breast cancer. We have pioneered immunotherapy trials using viruses to treat early-stage triple-negative breast cancer, and we have developed vaccines to administer to patients with HER2 breast cancer before and after chemotherapy. Our patients have access to these and other promising new treatment options through our robust portfolio of clinical trials.

Moffitt proudly stands at the forefront of breast cancer research. In recognition of our important contributions to the advancement of cancer treatment, the National Cancer Institute has awarded us the designation of Comprehensive Cancer Center. Moffitt is the only cancer center based in Florida to have earned this distinction.

At Moffitt, we know that every day counts after a breast cancer diagnosis, and we want to support you with compassionate care every step of the way. If you would like to speak with a cancer expert about your breast cancer treatment options, complete our new patient registration form online or call 1-888-663-3488. A referral is not required to request an appointment at Moffitt.


Cancer Research Institute – Immunotherapy for Breast Cancer
Cancer Research Institute – Immunotherapy Side Effects - Keytruda
Cancer Treatment Centers of America – What’s the Difference? Chemotherapy and Immunotherapy