The Voice

Doctors Enable Patients’ Bodies to Fight Lung Cancer Via Immunotherapy

Boosting the immune system can be an important part of lung cancer treatment, so today let’s dive into how the immune system works, and how doctors strengthen it to help treat lung cancer.

The two types of immune responses

There are two types of immune responses, the innate immune system and adaptive immune system, and they respond to germs and viruses in different ways and have different goals. Your innate immune system is made up of your skin and the mucous membranes or moist areas of your body (such as your mouth, eyes and nose). It feels gross when you sweat or sneeze, but from an immune system perspective it’s very effective at keeping germs and viruses from entering your body. Your innate immune system acts as the first line of defense against germs and viruses and responds to them within a few hours. It can prevent germs and viruses from entering the body, but if they do enter it cannot stop them from spreading, it can only try to flush them out. 

closeup of immune cells attacking a cancer cell

The adaptive immune response works more to stop bacteria and viruses once they are already in the body and cannot be flushed out by the innate immune system. The adaptive immune system works through a special type of white blood cells called scavenger cells, which can enclose germs and digest them. The scavenger cells travel through veins and arteries, and once they sense that a cell is a foreign body, they activate enzymes that set off a chain reaction. The first scavenger cell marks the invading cell and calls other scavenger cells in the bloodstream to neutralize the harmful invader. If bacteria or viruses do manage to affect the cells of the body, then we have natural killer cells that identify and destroy cells that are infected or likely to become a tumor.

The adaptive immune system is slower than the innate immune system because it takes so much time to identify which of the millions of cells in our body are germs. However, an adaptive immune response means that the body will “remember” that harmful organism so the body can respond faster the next time that germ or virus tries to enter.

Important components of the adaptive immune system

The adaptive immune system is made up of three types of cells: T lymphocytes (also called T cells), B lymphocytes (also called B cells) and antibodies. The strongest defense in this immune response comes from T cells. They are made in the bone marrow and activate other cells to start the immune response. They can detect and destroy cells that have been affected by viruses, and “remember” previous cells that the body has fought off.

B cells are also found in the tissue between the body’s cells, while antibodies are found in the blood and other bodily fluids. Antibodies detect germs and viruses and attach to them, to prevent them from attaching to the body. Antibodies also attract other immune system cells to help with the adaptive immune response. 

How can the immune system be used to treat lung cancer?

Immunotherapy is a treatment that uses the cells of our immune system to treat lung cancer. There are three major types of immunotherapy treatments.

The first treatment type is called immune checkpoint inhibitors. In a normal immune response, immune checkpoints work with T cells to make sure the body’s immune response (which can cause inflammation and other symptoms of being sick) isn’t too strong or damaging to healthy cells. It is like an off switch for T cells. However, sometimes with cancer, the immune checkpoint proteins send that signal at the wrong time and prevent T cells from destroying the cancer cells. Checkpoint inhibitors are drugs that block these malfunctioning checkpoint proteins and allow the T lymphocytes to kill cancer cells.

The second treatment option is called therapeutic vaccines. Many of the vaccines that we think of are to activate the adaptive immune system and prevent us from getting sick. Therapeutic vaccines use the sick person’s immune system to fight diseases that are already in the body. This type of immune therapy uses lab intervention to train white blood cells (T cells) to attack cancer cells more actively. Doctors take blood from their patients, expose the white blood cells to proteins that are often found on tumors, and then infuse those cells back into the patient’s blood. The modified T cells attack proteins that are only found in cancer cells and very rarely found in other cells.

The third immune-oncology approach, adoptive T Cell therapies, involves taking a patient’s cells, multiplying them, and reinfusing them to make them better able to fight cancer. There are two types of adoptive T cell therapies. The first is called tumor-infiltrating lymphocytes because these T cells go into a tumor instead of remaining in the bloodstream. In this treatment, doctors take blood from the patient, test the T cells in a lab to see which ones best recognize tumor cells and then multiply those successful lymphocytes and infuse them back into your bloodstream.

The other adoptive T-Cell therapy is called CAR T-Cell therapy, and it also works using the T cells in your bloodstream. “CAR” stands for chimeric antigen receptor. CARs allow the T cells to attach to specific proteins on the surface of the cancer cells, improving their ability to attack the cancer cells. CAR T-Cell Therapy works by changing your T cells so that they produce more chimeric antigen receptor proteins.

People with lung cancer should discuss with their oncologist which treatment options, including immunotherapies, are best for their specific type and stage of lung cancer. For more general information on the costs and benefits of immunotherapy, and where treatments may be headed next.

Upstage Lung Cancer’s podcast conversation with Dr. David Barbie

The innate and adaptive immune systems | NIH Library of Medicine
Immune Checkpoint Inhibitors | NCI
Lung Cancer Immunotherapy | American Lung Association