A couple of weekends ago, I spent some time visiting with friends at a cottage in Grey Bruce Country. Sunday morning, after watching France win the world cup in our pyjamas, the conversation turned to CRISPR. This was pretty surprising to me, since most people in the room did not have a science background. I realized CRISPR has become so famous it’s now common cocktail party chat. But, while I’ve been having a great summer, CRISPR has not.
In June, two articles were published in Nature Medicine suggesting the CRISPR-Cas9 gene-editing system can increase the risk of cancer in certain cells. Essentially, p53 is responsible for repairing damaged DNA. When genes are edited using CRISPR-Cas9, p53 interprets the DNA edit as damage and destroys it. By selecting cells which successfully incorporate the intended gene into their DNA, we may inadvertently be selecting for cells with impaired p53, leading to an increase in cancer.
A study published this Monday in Nature Biotechnology found large deletions and complex genomic rearrangements in two different types of mouse cell lines and a human cell line, which may have pathogenic consequences. This type of damage may not have been identified in previous studies because it is too far away from the target site to be detected with standard methods.
As human CRISPR trials continue to enroll patients this year, most researchers remain cautiously optimistic about the therapeutic possibilities of CRISP-Cas9. These studies highlight the need to proceed with caution, and now that we are more aware of the potential risks we can take them into account when developing therapies.