Researchers have created a new CRISPR-based approach that can selectively destroy cells carrying a mutation in a tumor suppressor found in nearly half of cancers and up to 70% to 90% of cases of some of the most difficult-to-treat cancers. The new approach harnesses CRISPR's ability to find cells with specific mutations and uses its cutting ability to selectively destroy those cells. Making treatments for different cancers using this technique is faster than making a small molecule drug or antibody therapy. Delivery remains a challenge, but a combination of therapies may prove useful for some cancers.