By Reagan Smith
From bacteria in the environment to internal infections, the human body’s immune system is constantly combatting dangerous outside forces. Fortunately, the immune system is armed with an arsenal of tools, such as white blood cells, the lymphatic system, and macrophages, which it utilizes to deal with these threats.
Now, one of the more dangerous threats that the immune system may have to deal with is cancerous cells. To combat cancerous cells, the human body utilizes tumor-infiltrating lymphocytes (TILs), which are a specialized type of lymphocyte that is not only able to destroy abnormal cancer cells, but can also prevent tumor growth. However, cancer cells can modify themselves through changed DNA, specialized cell surface proteins, and an altered surrounding cell matrix, which can inhibit the efficacy of TILs.
This is where a treatment called immunotherapy comes into play. Immunotherapy is a type of biological therapy that utilizes organic substances to treat patients with cancer. It essentially “hijacks” the immune system and stimulates it so that it can fight off cancer cells more effectively, thereby healing the body’s tissues. Immunotherapy consists of three unique treatment strategies: nonspecific immune stimulation, immune checkpoint inhibitors, and T-cell transfer therapy.
Nonspecific immune stimulation is somewhat generalistic, as indicated by the name. This treatment involves the usage of drugs and/or other organic substances in order to increase the patient's overall immune response to the cancerous cells. Typically, a nonspecific immune response is triggered to kill leftover cancer cells and prevent cancer from recurring.
Immune checkpoint inhibitors block immune checkpoints, which are a normal component of the immune system responsible for keeping it functioning properly. Without immune checkpoints, T cells can end up targeting healthy cells, which can cause critical damage to the human body. Checkpoints are engaged when immune checkpoint proteins on the cell surface of T cells recognize and bind to receptor proteins on other cells. When the two proteins bind, the T cell is shut down and prevented from destroying anything—even if their target is a cancerous cell.
By inserting a compound that blocks these checkpoints, the receptor protein is blocked, and thus the T cell is unable to be deactivated. Once this is done, the immune system can then be more effective against any cancerous cells. Current cancer types treated with this form of immunotherapy include breast cancer, bladder cancer, cervical cancer, skin cancer, stomach cancer, and several others.
The two subcategories of T-cell transfer therapy are TIL therapy and CAR T-cell therapy. Both begin with extracting T cells surrounding the tumor within the patient. A doctor will then select the most active T cells, which will then be incubated for reproduction purposes. This process can take anywhere between two to eight weeks. Meanwhile, the patient may undergo radiation therapy and/or chemotherapy in order to reduce the concentration of other immune cells in the body, which will increase the effectiveness of the selected T cells. These cells are then injected back into the body intravenously to fight the tumor.
While immunotherapy is not 100% effective, it has proven to be extremely beneficial to many recipients. For many, it serves as an alternative to chemotherapy and/or radiation therapy; however, despite this, it is not commonly used yet. Current focuses of research on this topic include solutions for resistance to immunotherapy, ways to predict a patient’s response to immunotherapy, understanding cancer cells’ response to the immune system, and methods to reduce side effects. One can only imagine how this cancer treatment method will be viewed a few decades from now.
Educational Content
What are TILs?
TIL stands for tumor-infiltrating lymphocytes. They are a specialized type of lymphocyte that destroys abnormal cancer cells and can prevent tumor growth.
What are the three common kinds of immunotherapy?
The three common types of immunotherapy include nonspecific immune stimulation, T-cell transfer therapy, and immune checkpoint inhibitors. All three methods involve boosting the immune system in order to help it fight against cancerous cells and tumors.
Why is immunotherapy not as commonly prescribed?
There can be unpredictable side effects depending on the recipient and the type of cancer, which may be harmful to the patient. As such, there is still much more research to be done in this area before immunotherapy becomes a common treatment for cancer.
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