Scientists May Have Found a Way to Treat All Cancers... By Accident | SciShow News

Thanks to Brilliant for supporting this episode of SciShow. Go to Brilliant.orgSciShow to learn how you can give the gift of learning to someone you love! People often wonder why there is still no cure for cancer. And the answer is usually because “cancer” is not a single thing. It's this great umbrella term for a bunch of different conditions where cells grow out of control. While there are

treat

ments for some types of cancer, different

cancers

are, well, different enough that there is nothing that works for all of them: there is no universal cure. But it turns out there could be?

Researchers at Cardiff University in Wales may

have

found

a way to

treat

all

cancers

, or at least many of them. And they just stumbled upon it. The researchers were not looking for cancer therapies. They were looking for ways to fight bacteria with immune cells called killer T cells. As their name implies, these cells kill things. Specifically, things that are not good for your body. But unlike other immune cells, they do not directly attack bacteria or viruses. Instead, they interrogate the body's own cells, trying to detect those that could be hiding pathogens inside. And when they find an infected cell, they kill it.

But not all killer T cells are the same. There are different types that use slightly different proteins, called receptors, to examine cells. Often these receptors are somewhat specific to the invader they seek. But the researchers were looking for a type of T cell that could detect many different bacteria. So, they extracted a bunch of killer T cells from blood samples and tested their ability to detect infections. It turns out that the test the team was using uses a type of cancer cell that is easy to infect with bacteria. And several different T cells showed promise when

scientists

unleashed them on these infected cancer cells.

But one was especially ruthless. Unfortunately, in later experiments, he killed all the cancer cells, not just the ones with bacteria inside them, so it wasn't what they were looking for. But it did spark his curiosity. Now, it's not so strange for a T cell to kill cancer cells, because T cells don't just look for infections. They are also in charge of keeping cancers under control. And in recent years,

scientists

have

begun to harness the power of these cells to fight cancer. In CAR-T immunotherapy, for example, T cells are removed from a person's body, genetically programmed with a receptor that can detect the person's cancer, and then injected back to search and destroy.

But we still can't do this for all cancer patients because we don't have good receptor targets for every type or even subtype of cancer. You know, that "not all cancers are the same" thing. But I digress. The point is, it wasn't very surprising that researchers had

found

a T cell that killed this particular type of cancer. But before simply dismissing them or setting them aside to continue the search for bacteria-killing T cells, they decided to see what happened with other types of cancer as well. And they worked. Against all of them. Lung cancer, colon cancer, bone cancer, breast cancer, blood cancer, skin cancer... these T cells killed every type of cancer the researchers tested.

Not only that, but they left healthy cells alone. Which is like, WOW! Needless to say, this sparked new research into how these T cells did this. To solve it, the researchers removed proteins from cancer cells one by one by editing the CRISPR-Cas 9 gene. The idea is that if removing a protein makes T cells ineffective, then that protein must be involved in the way cells detect cancer. And that led them to a protein called MR1. Now, the interesting thing about this is that MR1 can be found in all cells, not just cancer cells. You see, it is believed to be a kind of immune system informant.

It samples molecules from inside the cell and presents them to the outside, where immune cells can see them. And that's exactly what these killer T cells seem to be doing. They have a special receptor that allows them to interact with MR1 proteins and read those samples. They are not the only T cells that interact with MR1, but they appear to be the only ones we have found so far that can detect all types of cancer by doing so. The researchers were even able to take this receptor and insert it into T cells from real cancer patients.

Basically the same idea as CAR-T therapy, but using this protein instead of tailoring the T cells to each patient's specific cancer. And those engineered T cells not only killed samples of the patients' tumors, but they also killed cancers from multiple patients. This is probably because MR1 proteins don't actually differ much between people, so the same receptor can recognize them all. This means that instead of having to design individual therapies for each cancer, doctors could use this receptor to produce T cells that work for everyone. But we shouldn't open the champagne just yet. There are still some big unknowns here.

For example, researchers don't actually know how T cells recognize MR1. Seriously, the actual text of the article is that this quote from the receptor "does not recognize MR1 by known mechanisms." And they don't know what MR1 shows to T cells to alert them that the cell is cancerous; although presumably it is exclusive to cancers and, if not universal, at least super common. Most importantly, however, they have yet to test these T cells in real human patients. They tested them on mice that had been diagnosed with human cancers and the results were promising. But they still may not work well on a real, living person.

We'll know soon enough. The researchers' current plan is to proceed cautiously, and if safety testing goes well, they are hopeful that human trials could begin in the coming years. On the plus side, even if this doesn't lead to a citation as a “cure for cancer,” studying these T cells could help scientists discover new ways to treat many different types of cancer. And the team is already looking for other similar T cells that can kill multiple cancers. And to think: this discovery would never have happened if researchers hadn't had the good sense to investigate further when some cells did something strange.

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