Chimeric antigen receptor (CAR) T cell therapy is a new type of cancer treatment. During this treatment, healthcare professionals reprogram the immune system to attack cancer cells.
Healthcare professionals currently use CAR T therapy to treat some blood cancers. However, scientists are investigating whether or not it could also work in other cancers.
This article will explain what CAR T cell therapy is and how it works. It will also look at some possible side effects and the recovery process.
T cells are part of the immune system. They are a type of white blood cell with proteins on the surface that act as receptors.
T cells move around the blood, checking for foreign substances, such as viruses or bacteria. These foreign substances also have proteins on their surfaces. Experts call these proteins antigens.
Immune cell receptors and antigens fit together like a lock and key. Each foreign substance and T cell has a differently shaped antigen or receptor. T cells bind to antigens that fit their receptor, destroying the foreign substance.
Cancerous cells also have antigens. However, T cells rarely have the right receptor to bind to them.
CAR T cell therapy is a way of training the immune system to recognize cancerous cells. It is a type of gene or cell therapy.
Scientists add CARs to a person’s T cells. These new receptors help the T cells bind and destroy cancerous cells.
Different cancers have different antigens, and scientists must adapt the treatment accordingly.
Can it fail?
Success rates vary depending on the type of cancer a healthcare professional is using CAR T cell therapy to treat.
One 2017 review suggests that up to 90% of people with a specific form of leukemia fully recovered following this form of treatment.
However, the treatment is still very new. The Food and Drug Administration (FDA) approved the first CAR T cell therapy in 2017. So, there is still much to learn about how well it works.
Healthcare professionals may use CAR T cell therapy if traditional cancer treatments, such as chemotherapy, are ineffective or if the cancer returns.
The FDA have approved four CAR T cell therapies in the United States. Healthcare professionals can only use them to treat specific blood cancers in certain groups of people, as follows:
- Breyanzi is for adults with some types of reoccurring B cell lymphoma.
- Tecartus is for adults with reoccurring mantle cell lymphoma.
- Kymriah is for people under 25 years of age with leukemia and adults with reoccurring large B cell lymphoma.
- Yescarta is for adults with certain forms of reoccurring B cell lymphoma.
However, the U.S. National Library of Medicine list over 600 ongoing CAR T cell therapy clinical trials. Scientists are currently investigating the use of CAR T cell therapy in many types of cancer, including:
- colorectal cancer
- colon cancer
- ovarian cancer
- pancreatic cancer
- liver cancer
- lung cancer
- acute lymphoblastic leukemia
- non-Hodgkin lymphoma
- acute myeloid leukemia
- multiple myeloma
According to the American Cancer Society, receiving CAR T cell therapy can take a few weeks.
The process has three steps:
1. T cell collection
Healthcare professionals will collect the T cells through an intravenous (IV) line. This can take 2–3 hours.
Blood will flow from the person’s body into a machine that will remove the white blood cells. T cells are a type of white blood cell. The machine will then send the rest of the blood back through another IV line.
2. CAR T cell production
Healthcare professionals will separate the T cells from the rest of the white cells and send them to a laboratory. Scientists will then add CARs to the cells, creating CAR T cells.
The scientists will wait for the cells to multiply enough to fight cancerous cells before returning them. This part of the process can take a few weeks.
3. CAR T cell infusion
The next stage will be to insert the new CAR T cells into the person’s bloodstream through another IV line.
Healthcare professionals may recommend chemotherapy first to prepare the immune system for the new CAR T cells.
CAR T cell therapy can cause some side effects. The most common side effect is cytokine release syndrome (CRS).
Cytokines are chemical messengers in the immune system that support the T cells. Cytokines multiply when the CAR T cells enter the body, and this can lead to an overproduction of cytokines.
CRS can cause mild symptoms, including:
It can also cause some severe symptoms, such as:
- low blood pressure
- rapid heartbeat
- cardiac arrest
- heart failure
- hypoxia, or a lack of oxygen in the body’s tissues
- poor kidney function
- multiple organ failure
Severe CRS can also lead to neurological problems, including:
- language impairment
- involuntary muscle twitching
Serious CRS can be very dangerous. People with severe CRS will need immediate treatment in intensive care. Most of the symptoms are reversible, but CRS can sometimes be fatal.
People will usually have to stay in the hospital for observation after CAR T cell therapy. The observation period varies from hospital to hospital, but it is usually a few weeks.
Side effects can develop 1–21 days after treatment. People are also at higher risk of infection for 28–30 days after the infusion.
CAR T cell therapy is a new cancer treatment that trains the immune system to fight cancer cells. Scientists genetically modify T cells so that they can detect and fight cancerous cells. The treatment tends to be effective, but it also carries a risk of serious side effects.
CAR T cell therapy is a very new treatment that is currently only available for some blood cancers. However, hundreds of studies are currently investigating its use in other cancer types.