Skip to main content
Move the World.
Does CRISPR Cause Cancer?

The breakthrough gene editing technique CRISPR has a problem: it might only work by increasing the risk of cancer. Two studies published this week in Nature Medicine found that cells edited with CRISPR-Cas9 were more likely to develop mutations and become cancerous. That means therapies that involve replacing disease-causing genes with healthy versions and returning the modified cells to patients could ultimately seed tumors throughout their bodies.

Biotech investors are spooked, but most geneticists are taking the studies in stride. They believe that the problem is manageable, and some are doubtful that these lab results will translate to the real world.

Hurray, Efficiency! But Wait, Maybe Also Cancer?

The biggest problem with gene editing is that it's extremely inefficient: most of the cells that get CRISPR'd refuse the genetic changes. This makes it slow and expensive, and you have to do a lot of testing to find the cells that took the edits. Scientists managed to boost CRISPR's efficiency up to 80%, but, disturbingly, the edited cells were now much more likely become cancerous.

DNA Hates to Change

Your body really doesn't like it when something breaks your DNA—especially since the cause is usually a virus, chemicals, or radiation—so there's a genetic "kill switch," called p53, to stop cells with broken DNA from replicating. When CRISPR cuts both strands of DNA to insert a new gene, that triggers a chemical that activates the failsafe: the cell will either repair the cut (erasing CRISPR's insertion) or die. Either way, the new gene won't take.

Naturally Selecting for… Cancer

Scientists found a way to brute force the problem and get the share of cells who accepted the changes at the end to 4 out of 5. But Darwin warned us about natural selection 150 years ago. By forcing CRISPR-Cas9 into the DNA, you're weeding out the cells with a working failsafe. Those cells will self-destruct if they can't repair the edited DNA, and then you're left with a pool of cells that don't die when their DNA breaks.

And that leads to cancer. In fact, according to STAT News, malfunctioning p53 genes are responsible for a huge share of cancers: "nearly half of ovarian cancers; 43 percent of colorectal cancers; 38 percent of lung cancers; nearly one-third of pancreatic, stomach, and liver cancers; and one-quarter of breast cancers."

This is something that bears paying
attention to, but I don’t think it’s
a deal-breaker.

Erik Sontheimer , , Intellia Therapeutics

Who Want Some Caveats?

The bad news: our miracle gene therapy might cause disease, in addition to fixing it. The good news: there's lots of caveats that leave scientists room for hope and directions for improvement.

First, the cancer effect has never actually been seen in lab mice who have been treated with CRISPR-Cas9 (at least not yet). That doesn't mean it doesn't happen or that those CRISPR'd cells didn't increase the risk of cancer, but the effect might be rare in a real-world environment, rather than a petri dish. It could be that CRISPR's natural inefficiency has reduced the likelihood of cancer, or it could be that the body's other defense systems pick off the new cancer-prone cells.

Second, the problem only affects one kind of edit: swapping in a whole new gene for an old one. But the studies found that CRISPR can still delete disease-causing genes, like the one that causes sickle cell, without triggering the kill switch.

There are several other techniques that won't have this problem, either: CRISPR that uses enzymes other Cas9, editing T cells to fight cancer, and CRISPR 2.0 (which edits DNA letter by letter, rather than cutting the strand and swapping in a big chunk).

What It Means

The scientists behind the two studies think the best solution is just to be cautious with CRISPR-Cas9. The critical thing is just to make sure that cells do have a working copy of the p53 gene after getting CRISPR'd, and that can be checked pretty easily these days.

It might take more work than we expected, but you can always just culture the cells that both accepted the CRISPR edits and have a working failsafe until you have enough cells to do the treatment right. The takeaway is that, like everything in science, there are  risks and tradeoffs that have to be investigated.

Explore More Stories

Technology
The "Search Angel" Volunteers Reunite Birth Families
The "Search Angel" Volunteers Reunite Birth Families
Watch Now
Technology
The "Search Angel" Volunteers Reunite Birth Families
For some, not knowing their biological family can feel like a part of them is missing. The Search Squad is helping them for free.
Watch Now

These people are meeting biological relatives for the first time, thanks to a group of volunteers. The Search Squad group on Facebook has around 100 volunteer “search angels” who scour birth records and websites to find the birth relatives of adoptees. Many people who were adopted as children would like to meet their birth relatives, but it can often be an extremely expensive and time-consuming process. Search Squad, on...

Dispatches
How NASA Scientists Learned to Stick with Super Long-Term Goals
How NASA Scientists Learned to Stick with Super Long-Term Goals
Dispatches
How NASA Scientists Learned to Stick with Super Long-Term Goals
When the New Horizons spacecraft launched in 2006, Pluto was still a planet and the iPhone didn't exist.
By Bruce Barry and Thomas Bateman

When the New Horizons spacecraft launched in 2006, Pluto was still a planet and the iPhone didn't exist.

Dispatches
Will Probiotics Cure Cholera?
Will Probiotics Cure Cholera?
Dispatches
Will Probiotics Cure Cholera?
MIT scientists say eating good bacteria can prevent, cure, and diagnose cholera—cheaply.

MIT scientists say eating good bacteria can prevent, cure, and diagnose cholera—cheaply.

Dispatches
CRISPR Edits Out Autistic Traits in Mice
CRISPR Edits Out Autistic Traits in Mice
Dispatches
CRISPR Edits Out Autistic Traits in Mice
The technique could also open up treatments for Huntington's, schizophrenia, and epilepsy.

The technique could also open up treatments for Huntington's, schizophrenia, and epilepsy.

Superhuman
Can Virtual Reality Help Fight the Opioid Crisis?
Can Virtual Reality Help Fight the Opioid Crisis?
Watch Now
Superhuman
Can Virtual Reality Help Fight the Opioid Crisis?
VR has long been seen as an escape from the real world. But recently researchers have been putting an unexpected twist on that. They’re now exploring how VR could provide an escape from an unfortunate reality many face everyday: chronic pain.
Watch Now

Opioid addictions have become a dangerous side effect for many that take medications to treat chronic pain. To address this, doctors are exploring alternatives to prescriptions pain medicine. As part of this movement, Dr. Brennan Spiegel at Cedars-Sinai Hospital in Los Angeles has spear-headed some pretty fascinating research. He and his team are using virtual reality to reduce pain. Not only is it surprisingly effective...

Dispatches
Babies Sometimes Trigger Preterm Labor to Escape Infections
Babies Sometimes Trigger Preterm Labor to Escape Infections
Dispatches
Babies Sometimes Trigger Preterm Labor to Escape Infections
A new discovery upends what we thought we knew about premature births and could point the way to entirely new...

A new discovery upends what we thought we knew about premature births and could point the way to entirely new solutions to prevent them.

Superhuman
Brain Implant Gives Quadriplegic Movement
Brain Implant Gives Quadriplegic Movement
Watch Now
Superhuman
Brain Implant Gives Quadriplegic Movement
A brain implant connected to electrodes could offer hope to those who have lost function in their limbs.
Watch Now

A brain implant connected to electrodes could offer hope to those who have lost function in their limbs.A tragic diving accident while on vacation left Ian Burkhart unable to move most of his body. But a brain implant connected to electrodes on his arm restored his ability to move his fingers and could offer hope to those who have lost function in their limbs.

Superhuman
Superhuman Trailer
Superhuman Trailer
Watch Now
Superhuman
Superhuman Trailer
Join us as we meet the innovators building our superhuman future.
Watch Now

Superhuman is a Freethink original series about the amazing advances in medical innovation that are making the present look more like a sci-fi depiction of the future. Join us as we meet the engineers, entrepreneurs, doctors and patients who are giving people a new lease on life today, while building our superhuman future of tomorrow.