Immunotherapy is a type of systemic treatment (treating the whole body) that aims to boost the individual’s own immune system to fight cancer. Immunotherapies are a type of biologic therapy, as they are made from substances produced from organisms that are alive.1

Normally, the body’s immune system fights disease and infection. The white blood cells recognize and destroy damaged or diseased cells and foreign invaders, like bacteria and viruses. Cancer cells can often mutate in such a way to avoid detection by the immune system, and they grow out of control. Immunotherapies aim to help the immune system identify and destroy cancerous cells.1,2

There are several types of immunotherapy that are currently being studied or are approved for the treatment of advanced breast cancer, including:3

  • Monoclonal antibodies
  • Adoptive cell transfer

How immunotherapy works

Each type of immunotherapy has a different way of working. Monoclonal antibodies are made in the lab to work similarly to how antibodies produced by the body, work. They can target specific areas of cancer cells and/or the pathway that allows cancer cells to avoid immune system detection, such as blocking the function of specific proteins known as PD-L1 and PD-1. The PD-1 and PD-L1 proteins can help disguise cancer cells from the body’s T-cells (a type of white blood cell) and prevent the T-cells from attacking the cancer cells, allowing the cancer to continue to grow and survive. Certain monoclonal antibodies that target PD-L1 or PD-1 proteins disrupt this pathway and may be available as an approved, or clinical trial, treatment option for certain forms of advanced breast cancer.3

Monoclonal antibody treatments

In March of 2019, the U.S. Food and Drug Administration (FDA) granted accelerated approval for the first immunotherapy treatment for breast cancer. Tecentriq (atezolizumab) combined with the chemotherapy medicine Abraxane (nab-paclitaxel) is an option for certain patients with triple-negative breast cancer (TNBC) who have unresectable (non-operable) advanced or metastatic breast cancer.

The U.S. Food and Drug Administration (FDA) has also granted accelerated approval for Keytruda (pembrolizumab) for the treatment of locally recurrent unresectable or metastatic triple-negative breast cancer. For this approval, Keytruda must be combined with chemotherapy and the tumor must express the PD-L1 protein as measured by an FDA-approved test.4

Adoptive cell transfer technique and research

Adoptive cell transfer is an emerging immunotherapy technique that collects and uses the patient’s own immune cells to attack the cancer. In one ongoing Phase II clinical trial, researchers are using tumor-infiltrating lymphocytes (TILs), a type of white blood cell. Researchers first identify the specific mutations on the person’s cancer and identify which TILs can recognize them. These cells are removed from the patient’s body and grown in a laboratory to create a large number of them, which can take several weeks. During this time, the patient may be given treatments to reduce their immune cells. The TILs are then given back to the patient, where they can generate an immune response to fight the cancer cells.1,5

More on this topic

The current trial includes people with several different types of cancer. One patient with metastatic breast cancer has experienced her cancer disappearing from her body. Before participating in the trial, her metastatic breast cancer did not respond to multiple treatments, such as chemotherapy or hormone treatments. With this new immunotherapy, combined with a checkpoint inhibitor called pembrolizumab, all of her cancer has disappeared and has not recurred for at least 22 months. However, not everyone in the trial experienced the same results, and research is ongoing to determine which individuals are best suited for this therapy.5

Possible side effects from immunotherapy

Like all treatments, immunotherapy may cause side effects, although each individual responds differently and may not experience the same side effects as another. Common side effects experienced with certain immunotherapy medications include1:

  • Pain, redness, or soreness at the injection site
  • Flu-like symptoms, such as fever, chills, nausea, vomiting, and muscle or joint aches
  • Fatigue
  • Diarrhea
  • Heart palpitations
  • Swelling or weight gain

This is not an exhaustive list of all potential side effects of immunotherapies. Talk to your healthcare provider or pharmacist for further information. Before starting treatment with immunotherapy, patients should talk to their doctor about all their health conditions, as well as any medications (prescription and over-the-counter), vitamins, and herbal supplements they are taking. Some medications or supplements may interfere with each other and may cause side effects. Patients should talk to their doctor if they have any questions, or if they have questions regarding their immunotherapy regimen.

Clinical trials

Certain patients may be able to participate in clinical trials that are testing some of these new therapies. Clinical trials are an important part of the scientific process to find and prove the safety and effectiveness of new treatments, and they offer patients a chance to receive the latest treatments and be closely monitored by healthcare professionals. Talk to your doctor about whether clinical trials are a good option for you.

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Written by: Editorial Team | Last reviewed: October 2020.