David Liu

In 2021, David Liu couldn’t sleep after the U.S. Food and Drug Administration cleared the first clinical trial based on his research. Just five years earlier, he’d developed the technique that rewrites disease-causing DNA one letter at a time—with more precision and fewer side effects than previous tools that cut into the DNA, disrupting genes. Liu realized, with excitement and some trepidation, that his research was reaching patients much faster than the typical timeline. But the past year has brought plenty of reassurance. No fewer than 17 clinical trials are applying his research to various conditions including sickle-cell anemia and high cholesterol. “The power is that it’s programmable,” he explains. “The same editing machine can treat all of these diseases.” Four trials have reported positive results since January 2024, including one in March that helped people with a rare lung and liver disease. About 6% of the population will be affected by a disorder potentially reversible through what’s known as base editing. “It’s stunning and gratifying” for dozens of patients to have already benefited, Liu says, but his Harvard research team hasn’t slowed down. They’ve developed what may be an even more versatile approach, called prime editing, which entered its first clinical trial in 2024 as well. “It’s always been my dream to see our science benefit humanity,” he says. “I never would have believed it would happen so quickly.”