Harnessing the Immune System to Treat Ovarian Cancer

As with any disease, your body's immune system fights back against a cancer’s unusual cell growth. The major work of the immune system is done by white blood cells, your body's built-in disease-fighting agents, which ideally will target the tumor and attack its cells. However, not all immune responses are the same.

"My key interest is what we call tumor immunology," says Dr. Stefanie Avril, gynecologic pathologist at Case Western Reserve University in Cleveland. "That looks at how a person's immune system can fight against their cancer."

Boosting the Immune Response

Tumor immunology aims to discover why some patients' immune responses effectively fight off the cancer, while others’ are less effective. "We are trying to better understand why it sometimes works so well and can completely get rid of a cancer, and what we can do to make it better in those patients where it's not yet working perfectly," says Dr. Avril.

Researchers like Dr. Avril examine cancer tissue to analyze the white blood cells surrounding an ovarian tumor. They use advanced medical technology to determine how active those cells are, and to what extent they’re fighting the tumor.

What is Immunotherapy?

Tumor immunology can help researchers better understand what causes immune cells to activate and launch a response, so that they can develop new treatments for ovarian cancer. These treatments are called immunotherapies, and some have already been widely successful in reducing cancer deaths.

Immunotherapy takes advantage of the body's own immune system to attack the cancer, using medications and other treatments to trigger the immune response. "In gynecologic tumors and ovarian cancer in particular, in many cases the immune system needs extra help,” says Dr. Avril. “Additional treatments and drugs help it become more effective in fighting the cancer.”

Checkpoint Inhibitors

One promising avenue of immunotherapy is checkpoint blockades, also known as checkpoint inhibitors, which are medications that contain man-made versions of proteins our bodies make, called antibodies. Once the antibodies are given to someone with cancer, they shut down key proteins in immune cells that, if left on, would slow the immune response. In essence, these antibodies "wake up" the immune system to recognize and attack the cancer.

Checkpoint blockades work better on some types of cancers than others. They have been especially effective in treating "solid" cancers, or cancers of solid organs like the breast and ovaries, as opposed to cancers affecting the blood, like leukemia.

They also work best against "hot" cancers, which are cancers that generally become inflamed due to an immune response. Cancers that are considered "hot" include melanoma and liver cancer.

"Cold" cancers are those that generally do not cause a strong immune response. Ovarian cancer, prostate cancer, and pancreatic cancer are all classified as cold cancers, because triggering an immune response is a bigger challenge. Scientists and doctors are working to discover how to change this.

"Part of this effort is to create a larger archive and biorepository of tumor specimens," says Dr. Avril. Oncologists like Dr. Avril take samples of patients' cancers, which are stored, along with clinical information such as:

• The type of cancer
• The cancer’s stage and grade
• The patient’s risk factors
• The response to treatment
• Whether the cancer recurred after treatment

Having a large archive of this information will allow experts to better understand tumor immunology in ovarian cancer, and create better immunotherapies in the future. As of now, there are no approved immunotherapies for ovarian cancer, but a few treatments are under investigation in clinical trials. If you are interested in participating in one of these studies, talk to your gynecologic oncologist to see if there are any trials that would be a good option for you.

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