On Saturday, researchers reported the first data indicating that the experimental treatment worked, causing levels of the destructive protein to plummet in Doherty's body and the bodies of five other patients treated with the approach. "I feel fantastic," Doherty says. "It's just phenomenal." The advance is being hailed not just for amyloidosis patients but also as a proof-of-concept that CRISPR could be used to treat many other, much more common diseases. It's a new way of using the innovative technology. "This is a major milestone for patients," says Jennifer Doudna of the University of California, Berkeley, who shared a Nobel Prize for her work helping develop CRISPR. "While these are early data, they show us that we can overcome one of the biggest challenges with applying CRISPR clinically so far, which is being able to deliver it systemically and get it to the right place," Doudna says.