Such work is already underway. Scientists at the Broad Institute and the Dana-Farber Cancer Institute have launched Project Achilles—an initiative that will use CRISPR to search for specific weaknesses in over 500 cancer-cell lines.
“This is a great demonstration of the impact of CRIPSR,” says Aviv Regev at the Broad Institute. “It’s truly better than the tools we had before; it lets us ask crisp questions and get precise answers.” It’s also increasingly versatile, she says. Although scientists initially used it to delete genes, they can now use it to switch genes on, or to gently turn their activity down a notch.
But even CRISPR has its limits. Sabatini says that it’s not great for studying regions of the genome that have been copied many times over. According to few upcoming papers, when CRISPR targets these amplified regions, it cuts all the copies and induces a generic toxic response in the affected cell. “Almost all human cancer lines have amplifications,” says Sabatini, “so if you want to know what the genes there are doing, you can’t do it through CRISPR.” Or, at least, not yet.