Can Your Own Cells Cure Cancer?

Have you ever heard of CAR-T? No, it’s not the kind of car you would drive down the road. CAR-T is a type of cancer immunotherapy that uses a patient’s own cells to destroy cancer cells in their body. CAR-T stands for the Chimeric Antigen Receptor that is placed on the T cells of a person with cancer. In this way, the cells can fight the disease!

Let’s look at how this works in more detail.

How does CAR-T therapy work?

T cells are a type of white blood cell in your blood that help you fight bacterial and viral infections such as the common cold. T cells are pretty effective at what they do. But they can’t always detect cancer cells, so they can’t always fight them. To make them even more effective, a cancer patient’s T cells must be extracted (taken out) and made into super-cancer-fighting T cells called CAR-T cells.

In a hospital or doctor’s office, a medical assistant uses a technique called apheresis to take out only the T cells in a cancer patient’s blood. The assistant then returns other parts of the blood to the person’s body. Finally, the assistant sends the patient’s T cells off to a manufacturing site.

At the manufacturing site, a laboratory technician genetically engineers a patient’s T cells. They make changes that allow the T cells to produce chimeric antigen receptors, or CARs. CARs help the T cells recognize a specific marker on cancer cells. These are no longer simple T cells that everyone has in their blood. They are CAR-T cells: super-strong-cancer-fighting T cells! So now, all that’s left is for a medical assistant to infuse (put in) these CAR-T cells back into the patient. The body starts producing more like them. Then, those cells will start attacking the cancer!

How does CAR-T therapy treat leukemia? 

Now let’s look at a specific example. Leukemia, which is cancer of the blood or bone marrow, is the most common type of childhood cancer in Canada. A specific type of leukemia called acute lymphoblastic leukemia (ALL) is usually treated with chemotherapy. But some patients do not respond to this treatment. Pharmaceutical companies (companies that research, manufacture and sell medicine) designed a CAR-T therapy, called tisagenlecleucel, that could help these children.

First, the researchers isolated T cells from the children participating in the trial. Then, laboratory technicians genetically engineered the T cells with special CARs. These CARs were specifically engineered to recognize the protein CD19, which is found on the ALL cancer cells.

After three months, doctors and nurses tested the patients who were treated with these CAR-T cells. Many of them went into remission after therapy. Some patients even had no signs of cancer!

What is the future of CAR-T?

CAR-T has made many cancer treatments possible, and it’s a hot topic in cancer research. In 2017, the United States Food and Drug Administration (FDA) approved two CAR-T therapies. The FDA regulates food production, medicine, cosmetics and vaccines in the United States. 

Here in Canada, Health Canada has approved use of one CAR-T based treatment. The Canadian Agency for Drugs and Technology in Health, which advises Canadian health providers, suggests the cost of treatment needs to drop before they recommend its use (2). In 2019, the cost of the treatment itself was high: between $490,000 and $635,000. And those numbers don’t include the cost to administer and watch over the patient. Only five places in Canada have the treatment, so there is also the cost of getting patients to and from the few places equipped to deliver it. It has helped patients where conventional techniques were not successful, but it did not work all the time. There can be serious side-effects. Because the treatment is so new, scientists don’t know for sure what long-term health risks there might be.  

Nonetheless, there are reportedly at least 20 CAR-T based treatments being studied in the US. As scientists continue to experiment, techniques like these hold out hope for more cures in future.