by Tammi Noonan
Some of the most promising advances in cancer research in recent years involve treatments known as immunotherapy. Unlike chemotherapy that directly kills cancer cells, immunotherapy is a type of cancer treatment that helps your immune system fight cancer. Immunotherapy helps us fight cancer by stimulating our immune systems to work harder or smarter to attack cancer cells, or by giving your immune system components, such as man-made immune system proteins. Immunotherapy works better for some types of cancer than for others.
To better understand immunotherapy in cancer treatment, we need to understand our immune system better. Your immune system is a collection of organs, special cells, and substances that help protect you from infections and other diseases. Immune cells and the substances they make travel through your body to protect it from germs that cause infections. The immune system keeps track of all the substances normally found in the body. Any new substance that the immune system doesn’t recognize raises an alarm, causing the immune system to attack it. For example, germs contain substances such as proteins that are not normally found in the human body. The immune system sees these as “foreign” and attacks them. The immune response can destroy anything containing the foreign substance, such as germs or even some cancer cells.
The immune system has a tougher time targeting cancer cells because cancer starts when native cells become altered and start to grow out of control. Sometimes the immune system doesn’t see the cancer cells as foreign because the cells aren’t different enough from normal cells. Other times the immune system recognizes the cancer cells, but the response might not be strong enough to destroy the cancer. Cancer cells themselves can also give off substances that keep the immune system in check, almost like they are camouflaged. To overcome this, researchers have found ways to help the immune system recognize cancer cells and strengthen its response to destroy them.
There are several types of immunotherapy used to treat cancer, some of the more common types of immunotherapy treatments used are:
Checkpoint inhibitors. These are the most widely used form of immunotherapy. The drugs, such as pembrolizumab (Keytruda) and nivolumab (Opdivo), help the immune system respond more strongly to a tumor. Checkpoint inhibitors do not target the tumor directly, instead they take the “brakes” off the immune system, which helps it to recognize and attack cancer cells.
Monoclonal antibodies. These are man-made versions of immune system proteins. The antibodies, such as bevacizumab (Avastin) and rituximab (Rituxan) are designed to attach to specific targets found on cancer cells. Monoclonal antibodies mark cancer cells so that they will be better detected and destroyed by the immune system.
Adoptive cell transfer or cell therapy. This is a treatment that attempts to boost the natural ability of your T cells (a part of your white blood cells) to fight cancer. In this treatment, (CAR-T cell therapy), T cells are taken from your tumor. Those that are most active against your cancer are altered genetically and grown in large batches in a lab. After a few weeks, these cells are given back to the patient as an infusion. During the time the cells are grown in the lab, you may have treatments such as chemotherapy and radiation therapy to allow the treatment to work more efficiently.
Like other forms of therapy, immunotherapy can cause side effects but most people experience fewer and milder side effects compared to chemotherapy. Common side effects include constipation, cough, diarrhea, fatigue, flu-like symptoms, skin reactions, swelling, nausea, and muscle aches.
Although immunotherapy has been extremely successful in some cases, it still only works in select groups of patients. Immunotherapy is not yet as widely used as surgery, chemotherapy, and radiation therapy for treating cancer, but the circle of cancer types approved for immunotherapy treatment is quickly widening. The field of immunotherapy is rapidly evolving and because of this, patient outcomes are consistently improving as a result of these drugs.
Editors note: Tammi Noonan, DNP ARNP, practices with the Medical Associates Oncology Department in collaboration with Eric Engelman, DO, and Christine Holm, MD.
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