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CAR T Cell Therapy


Chimeric Antigen Receptor (CAR) T-cell therapy is one of the most innovative cancer treatment methods I have ever encountered.

Such a form of treatment works based on altering the genes in a patient’s white blood cells so that they become immune T cells that help trigger the immune system to destroy cancer cells.


Our immune system is somewhat like a burglar alarm that most people have in their homes to say in layman’s language.

Our immune system treats foreign substances like burglars. It becomes an attacker as soon as it detects any foreign and unwelcome substances in the body and works to mitigate their presence.


CAR T cell therapy works along the same lines, it is a way to get immune cells called T cells which are a type of white blood cells that trigger a response by the immune system that destroys cancer cells.

A patient’s white blood cells are taken and altered in a lab by altering the genes in the white blood cells. This is also the reason why T-cell therapy is known as cell-based gene therapy.


How does T-cell therapy work?

What is its success rate?

Is it effective enough?


All these questions are answered here in detail.


The immune system detects the presence of foreign substances by sensing the presence of proteins known as antigens.

Antigens are usually found on the surface of such substances.

Similarly, T-cells have proteins on their surfaces called receptors that attach to the antigens of foreign substances. This in turn triggers a high alert response by the immune system to destroy such substances.


Antigens and T-cell receptors have a lock-and-key kind of relationship.

Only the correct key can fit the lock. Similarly, only a certain unique receptor can attach to a specific antigen. Cancer cells have certain antigens but if your immune cells don’t have the right receptors then the T-cells cannot attach to the antigen and destroy the cancer cell.

Different cancers have different antigens, each CAR is made for a specific type of cancer.

For example, in certain leukemia or lymphoma, the cancer cells have an antigen called CD19. Thus, to treat such leukemia or lymphoma, in CAR T-cell therapies, the cells are altered in such a way that they have the appropriate CAR to attach to the CD19 antigen.


Such therapy works where different numerous treatment plans have faltered.


T-cells are made by getting a patient’s white blood cells through a process called leukapheresis. During this procedure, the patient is instructed to lie down or sit down on a chair for about 2-3 hours in the passage of which 2 IV lines are used or a central venous catheter is used to remove blood from one IV through which white blood cells are extracted or separated and then the second IV is used to put the blood back into the patient’s body.

One of the side effects of the process is the lowering of blood calcium levels which can cause muscle spasms, numbness, and tingling. This can be treated by restoring calcium levels through an IV or by mouth.

Another drawback of such a treatment is that the multiplication and creation of T-cells take several weeks as a large number of such cells are required for treatment.


In studies, 9 out of 10 people with acute lymphoblastic leukemia whose cancer didn't respond to other treatments or whose cancer came back had full remission with CAR T-cell therapy. Remission means the cancer can't be detected in tests.

CAR T-cell therapy works best when there are significant amounts of cancer cells present in the body and the presence of other immune cells is lower thus the patient is given some chemotherapy to reduce the presence of immune cells, this round of chemo is not very strong so that no. of cancer cells is not reduced in the process as we know T cells work best when there are some cancer cells are left to attack.


While understanding the success of such a treatment plan, unfortunately there exist life-threatening side effects. Thus, patients must be observed closely for several weeks after receiving T-cells

Side effects due to CAR T-cell therapy:

  1. Cytokine Release Syndrome (CRS)

  2. Nervous system problems like headaches, changes in consciousness, shaking, twitching, seizures, loss of balance and confusion, and agitation.

  3. Allergic reactions during the infusion

  4. Abnormal levels of minerals in the blood, such as low potassium, sodium, or phosphorous levels. A weakened immune system, with an increased risk of serious infections. Low blood cell counts, can increase the risk of infections, fatigue, and bruising or bleeding.

I hope this article simplifies understanding the working and process of CAR T-cell therapy for you and addresses all your questions and concerns regarding such treatment.


 

Sources:

https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/car-t-cell1.html

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