Immunotherapy. It’s the latest buzzword in cancer treatment. It all seems so simple. If scientists can create a vaccine to protect a person against mumps and measles, why not cancer? Indeed, we have already seen a preventative cancer vaccine for cervical cancer, so why not all cancers?
In July I had the privilege of attending the National Breast Cancer Coalition’s Project LEAD® Institute and learned about the basics of the body’s immune system and how it might be applied to breast cancer. Researchers Stephanie Goff and Sasha Stanton taught two sessions on immunology to about fifty breast cancer advocates gathered to learn the basics of cancer biology and how to understand the latest research.
The immune system is the body’s defense against foreign invaders. We see it at work every day. A splinter pierces our skin, and the body sends immune cells to prevent an infection. We catch a cold, but most of the time our immune system fights off those foreign germs, and we get better. If we are in cancer treatment, our doctors warn us that our immune system is compromised, and that we need to stay away from crowded places where we might catch a cold or the flu, and not be able to fight it off.
At Project LEAD®, I learned that the immune system is much more complicated than the diagram of white blood cells fighting a germ I studied in high school biology. Many different types of cells and molecules, such as T-cells, work in a complicated chain of events to protect the body from disease. Working to find ways to use the immune system to fight breast cancer, scientists have targeted different aspects of that chain for which to design clinical trials.
Teaching the immune system to recognize the danger of cancer cells. One reason the immune system may not stop cancer from growing is because cancer cells are already the body’s own cells. True, they have experienced a mutation and started growing much too fast, but the immune system may not see them as foreign invaders that need to be killed. So one approach of immunotherapy is to teach the immune system that cancer cells are “non-self” thus activating T-cells to attack the cancer.
Developing checkpoint blockade drugs. The immune system uses a complicated system of checkpoints to make sure that it is just killing invaders and not healthy tissue. The checkpoints are like brakes to make sure the immune system doesn’t get out of control. Cancer cells are smart. When T-cells try to kill cancer cells, the cancer cells may be able to evade the immune system by increasing the substances needed in the chain of events necessary to kill just the invader cells and not the normal ones. So another approach in immunotherapy is called checkpoint blockade. These drugs stop the cancer cells from blockading the immune system. Checkpoint blockade drugs are already approved for metastatic melanoma, and others are in Phase 1 clinical trials for breast cancer.
Strengthening the immune system--TILs. Of course, some people’s immune systems do seem to work against their breast cancer. The body produces tumor infiltrating lymphocytes (TILs) to fight the tumor. Scientists have learned that patients who have more TILs have a better prognosis than those who have fewer. So another immunotherapy approach is use a cancer vaccine to increase TILs. This is more complicated than it sounds because breast cancer is not just one disease, and any person’s tumor is made up of many types of cells.
Researchers have identified at least five different approaches to possible vaccines. For example, in a procedure called adoptive transfer of tumor infiltrating lymphocytes, part of a patient’s tumor is removed, the cells are cultured in the lab to increase the TILs and then the TILs are put back into the patient’s body.
Cancer vaccines have worked best on cancers with a high number of cell mutations such as melanoma. The kind of breast cancer that best fits this description is triple negative breast cancer, so researchers are particularly interested in vaccine development for triple negative patients.
Finding a preventative vaccine. So far most of the research has been in the area of therapeutic vaccines--vaccines that are used in a person with breast cancer to prevent recurrence. Wouldn’t it be better to stop the disease before it ever starts? A preventative vaccine is the best solution to ending breast cancer. It already exists for the most common type of cervical cancer because the HPV virus causes cervical cancer, and scientists know how to make vaccines against viruses.
The cause of breast cancer is not yet fully understood, and there are many types of breast cancer. Researchers tend to focus on just one area to study, so too often what they learn isn’t shared across disciplines. The National Breast Cancer Coalition has developed a program called the Artemis Project® to know how to eliminate breast cancer by January 1, 2020. The Breast Cancer Deadline’s goal is to get researchers, lawmakers, and advocates working together to develop a preventative vaccine and to prevent metastases. Having researchers from different institutions and different fields of study meet together has led to new collaborations that will lead to the breakthroughs we wish for so desperately.
You will be reading more in the days to come about cancer immunotherapy. It’s the new darling in the research world. So far most of the news you see will be about other forms of cancer, but the breast cancer breakthroughs will come. For now, the action is in clinical trials. The National Cancer Institute list of clinical trials currently has 14 open trials related to breast cancer immunotherapy. Check with your doctor about an immunotherapy clinical trial if you are interested.
For more on breast cancer and promising treatments:
Goff, S. and Stanton, S. Immunology 101. Lecture presented at Project LEAD® Institute. San Diego, CA. July 2015.
How Immunotherapuetics Work. Transforming Lives Through Research. Cancer Progress Report. American Association for Cancer Research. Accessed from http://cancerprogressreport.org/Slides/SB28_2014.jpg August 16, 2015.
Loi, S. Immune Targeting in Breast Cancer: In Whom and With What? Oncology Journal Breast Cancer. May 15, 2015. Accessed from http://www.cancernetwork.com/oncology-journal/immune-targeting-breast-cancer-whom-and-what?GUID=E516FC5C-7604-40FE-85E6-8F7CE4923438&XGUID=&rememberme=1&ts=22052015 August 12, 2015.
Paddock, C. Scientists discover molecule that helps cancer cells evade immune system. Medical News Today, Oct. 8, 2014. Accessed from http://www.medicalnewstoday.com/articles/283604.php?tw August 16, 2015.
What is cancer immunotherapy? American Cancer Society. July 23, 2015. Accessed from http://www.cancer.org/treatment/treatmentsandsideeffects/treatmenttypes/immunotherapy/immunotherapy-what-is-immunotherapy August 16, 2015.