CAR T-cell Therapy and Its Side Effects
CAR T-cell Therapy and Its Side Effects
Your immune system works by tracking all substances naturally present in the body. Any new substance that the immune system does not recognize triggers an alarm, causing the immune system to attack it.
Chimeric Antigen Receptor (CAR) T-cell therapy is a method of taking immune cells called T cells (a type of white blood cell) and modifying them in the laboratory so they can find and destroy cancer cells. CAR T-cell therapy is sometimes referred to as a type of gene therapy based on cells, as it involves altering genes within T cells to help them attack cancer.
This type of therapy can be very effective in treating certain types of cancer, even when other treatments do not work.
How Does CAR T-cell Therapy Work?
Immune Receptors and Foreign Antigens
The immune system recognizes foreign substances in the body by finding proteins called antigens on the surface of those cells. Immune cells called T cells have their own proteins called receptors that bind to foreign antigens and help stimulate other parts of the immune system to destroy the foreign substance.
The relationship between antigens and immune receptors is akin to a lock and key. Just as a lock can only be opened with the correct key, each foreign antigen has a unique immune receptor capable of binding to it.
Cancer cells also have antigens, but if your immune cells do not have the correct receptors, they will not be able to bind to the antigens and help destroy the cancer cells.
Chimeric Antigen Receptors (CARs)
In CAR T cell therapies, T cells are taken from the patient’s blood and modified in the laboratory by adding a gene for a man-made receptor (called a chimeric antigen receptor or CAR). This helps them better identify cancer cell antigens. The CAR T cells are then returned to the patient.
Since different cancers have different antigens, each CAR is manufactured for a specific cancer antigen. For example, in certain types of leukemia or lymphoma, cancer cells have an antigen called CD19. CAR T cell therapies designed to treat these cancers bind to the CD19 antigen and will not work with cancer that does not have the CD19 antigen.
What Is CAR T-cell Therapy?
CAR T-cell therapy (Chimeric Antigen Receptor T-Cell Therapy) is an advanced form of immunotherapy aimed at treating certain types of cancer, especially hematological malignancies such as leukemia and lymphoma. The treatment involves modifying the patient’s immune cells to enhance their ability to recognize and attack cancer cells.
How Does CAR T-cell Therapy Work?
- Collecting T Cells: The treatment begins with collecting T cells (a type of white blood cell) from the patient’s blood. This is done through a process known as “leukapheresis.”
- Modifying Cells: The T cells are sent to a lab where they are genetically modified using a technique called “Chimeric Antigen Receptor” (CAR). This involves introducing a new gene into the T cells to carry a “Chimeric Antigen Receptor” (CAR) that can recognize specific antigens on the surface of cancer cells.
- Amplifying Cells: After modification, the T cells are multiplied in the lab until they reach a sufficient number for treatment.
- Reinjecting Cells: The modified T cells are then returned to the patient through a blood transfusion, where they are now able to recognize and attack cancer cells more effectively.
Benefits and Challenges
Benefits:
- Targeted Approach: CAR T cells can target cancer cells more specifically, reducing damage to healthy cells.
- High Efficacy: In some cases, studies have shown that CAR T cell therapy can be extremely effective in achieving complete or long-lasting responses, even in cases where other treatments have failed.
Challenges:
- Side Effects: These therapies can cause serious side effects, such as “Cytokine Release Syndrome” (CRS), an excessive immune response that can lead to fever, low blood pressure, and organ failure.
- High Cost: CAR T-cell therapy is considered very expensive, which may pose a challenge to access for some patients.
- Preparation Time: The therapy requires a preparation period for modifying the cells in the lab, meaning treatment may not be available immediately.
Clinical Applications
CAR T-cell therapy is primarily used to treat certain types of hematological cancers, such as:
- Leukemia: Especially acute lymphoblastic leukemia (ALL) that has not responded to other treatments.
- Lymphoma: Including large B-cell lymphoma (DLBCL).
Studies and research indicate that CAR T-cell therapy may have future applications in treating other types of cancer as well as improving current treatments.
Summary
CAR T-cell therapy is an advanced innovation in the field of immunotherapy that offers great hope for patients with certain types of cancer. By precisely targeting cancer cells, the therapy shows promising results, but challenges remain regarding side effects and costs. As research and developments continue, this treatment may become more common and affordable in the future, enhancing recovery prospects for more patients.
Obtaining CAR T-cell Treatment
The CAR T-cell therapy process can take several weeks.
- Collecting T Cells: First, white blood cells (which include T cells) are removed from the patient’s blood using a procedure called leukapheresis. During this procedure, patients usually lie in bed or sit in a reclining chair. Two intravenous lines are needed because blood is drawn through one line, white blood cells are separated, and then blood is returned to the body through the other line. Sometimes, a special type of intravenous line called a central venous catheter is used, which contains both lines.
Patients will need to stay seated or lying down for about 2 to 3 hours during the procedure. Occasionally, calcium levels in the blood can drop during leukapheresis, leading to numbness, tingling, or muscle spasms. This can be easily treated by replenishing calcium, which can be given orally or intravenously.
Side Effects of CAR T-cell Therapy
CAR T-cell therapy can be very effective against certain difficult-to-treat cancers, but it can sometimes cause serious or even life-threatening side effects. For this reason, it should be administered in a medical center specifically trained to use it, and patients need to be closely monitored for several weeks after receiving CAR T cells.
- Cytokine Release Syndrome (CRS): As CAR T cells multiply, they can release large amounts of chemicals called cytokines into the bloodstream, which can amplify the immune response. Serious side effects of this release may include:
- Fever and chills
- Difficulty breathing
- Severe nausea, vomiting, and/or diarrhea
- Dizziness or lightheadedness
- Headaches
- Rapid heart rate
- Severe fatigue
- Muscle and/or joint pain
As doctors gain more experience with CAR T-cell therapy, they learn how to recognize CRS early, as well as how to treat it.
- Neurological Problems: This therapy can sometimes have serious effects on the nervous system, leading to symptoms such as:
- Headaches
- Changes in consciousness
- Confusion or agitation
- Seizures
- Tremors or shaking
- Problems with speaking and understanding
- Loss of balance
Due to the risk of these side effects, adult patients are usually advised not to drive or operate heavy machinery or engage in any other potentially dangerous activities for at least several weeks after receiving treatment.
- Other Serious Side Effects: Other potential serious side effects of CAR T-cell therapy may include:
- Allergic reactions during the infusion
- Abnormal levels of minerals in the blood, such as low potassium, sodium, or phosphorus levels
- Weakening of the immune system, with an increased risk of serious infections
- Low blood cell counts, which may increase the risk of infection, fatigue, bruising, or bleeding
If you are receiving CAR T-cell treatment, it is very important to inform your healthcare team of any side effects immediately, as there are often medications that can help treat them.
All of the mentioned side effects may occur in some patients, but these symptoms can be managed and treated, and they are not necessarily dangerous. Saving the patient’s life is more important than worrying about some minor side effects that can be treated and controlled.