CAR T-Cell Therapy

Potential cancer therapy? You’ve got yourself a headline. And CAR T-cell therapy, a new cancer treatment, is no exception.

Let’s run through some basics first.

The human body protects itself from harm using its immune system – a group of specialized cells that cooperate to hunt out and destroy potential threats. We tend to think of dangers to our body as something that invades it (like bacteria), but our own cells can become harmful, too.

Cancer. The word alone is enough to make your heart sink.

Scariness aside, cancer is very broad term. It refers to a group of diseases in which your own cells grow uncontrollably. They often form tumours, and can spread to other places in the body.

tumour formation
Image source: Cancer Research UK via Wikimedia Commons

That’s a basic definition, but check out the NCI website if you want to learn more.

Surprisingly, we only recently worked out that our immune system can detect and destroy cancer cells. This led to the development of immunotherapy, a new group of cancer treatments designed to boost our immune system to fight cancer.

Chimeric Antigen Receptor (CAR) T-cell therapy is a type of immunotherapy that has made headlines across the globe. But what is it?

T-cells are part of the immune system, and can recognize dangerous cells in our body. They can destroy them directly, or recruit other immune cells to help finish the job. CAR T-cell therapy involves editing a patient’s T-cells to help them fight cancer.

Sounds complicated. How?

Cells have molecules on their surface that act as markers, telling the immune system what’s going on inside it. Cancer cells often have different sets of markers to normal cells, which can help them to escape the immune system. Now, scientists are trying to use this difference to treat cancer. Here’s how:

First, T-cells are extracted from the patient’s blood. A virus is used to deliver a set of instructions to these T-cells, which tell them how to make a special receptor. Once made, this chimeric antigen receptor (CAR) is put on the surface of the T-cells. The receptor will bind to a certain type of marker on the surface of cancer cells, so the T-cell can recognize them.

Wait…chimeric?

If you’re a bit of a mythology geek, you’ll know that the chimera is a mythical creature made up of bits of different animals. CARs are also a mosaic of different parts, which tell the T-cell to do different things. Together, they increase its ability to destroy cancer cells.

CAR T cell labelled
The different coloured blocks represent the different parts of the receptor. Image by Vanessa Place.

So, we’ve modified the T-cells in the lab so they now have CARs on their surface. These cells are encouraged to grow and divide, then put back into the patient. Hopefully, they will survive in the body. Using the CAR, the modified T-cells should be able to recognize and kill cancer cells. This video sums it all up:

Pretty amazing, right?

The success of CAR T-cells in clinical trials generated a lot of excitement. They are currently only effective against blood cancers, but in the future they may be suitable to treat other types of cancer.

As you’ve probably guessed, CAR T-cell therapy isn’t without problems:

Cost: it’s expensive.

Risk: several people have died in clinical trials . Doctors think this was because the T-cells reacted badly with other drugs given to the patients. Another major risk is a potential side effect called the cytokine storm – an out-of-control response by the immune system that can be fatal.

Should we believe the hype?

As I’ve mentioned in other posts, I don’t believe that all journalists over-hype science news. Yet some do, throwing around words like “cure” that raise hopes prematurely.

Like anything else, CAR T-cell therapy has its drawbacks. Yet, I’m going to stick my neck out and say that I (cautiously) believe in this therapy.

Don’t get me wrong, CAR T-cell therapy is far from perfect. Researchers across the world are still working hard to refine and improve it. It could be a big step on the rocky road to treating cancer.

behind the hype logo

One thought on “CAR T-Cell Therapy”

  1. Thanks so much for this post! I found it very informative and easy to understand. Have always been interested in the facts behind headlines related to science.

    Like

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