The U.S. Food and Drug Administration on Tuesday approved leucovorin, a synthetic form of vitamin B9, as a treatment for a rare genetic condition that causes folate deficiencies in the brain. The decision comes just months after U.S. president Donald Trump, Secretary of Health and Human Services Robert F. Kennedy, Jr., and FDA chief Marty Makary lauded the drug as a treatment for autism. After a scientific review, the FDA, which falls under Kennedy’s oversight, determined that there weren’t enough data to support that use of the drug.
“Autism is not caused by a folate deficiency,” says David Mandell, a professor of psychiatry at the University of Pennsylvania, who studies autism. “The data suggesting so are outdated and weak.”
Leucovorin is typically used to manage cancer patients’ side effects from chemotherapy. But last September Makary said the FDA would move to make the drug “available to children with autism.” Now the agency has approved its use for cerebral folate deficiency—a rare genetic condition that may affect fewer than one in a million people, though its true prevalence is unknown. It is caused by a mutation on the FOLR1 gene and can produce some similar symptoms to autism, such as communication issues. But autism is a separate condition, and a broad diagnosis. Although it can sometimes be tied to specific genetic factors, many researchers believe autism has no single cause.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
"There is a strong rationale for prescribing leucovorin for this specific condition," says Helen Tager-Flusberg, a psychologist and autism researcher at Boston University, adding that she was glad the FDA had been clear that there was no evidence to suggest it could treat autism. "[Cerebral folate deficiency] is a very different neurological disorder, and importantly the FOLR1 gene has never been association with autism," she says.
The FDA’s decision is welcome, Mandell says, but it won’t undo the interest the Trump administration has raised in using the drug for treating autism. “Pandora’s box is already open,” he adds. Prescriptions for off-label leucovorin—that is, for using the drug to treat a condition it isn’t approved for—have skyrocketed among children by 71 percent after the officials touted its potential benefits for autism. Tager-Flusberg says that it remains to be seen how the FDA’s decision will affect off-label use.
“RFK, Jr.’s premature and ill-informed announcement that leucovorin can cure autism led many families to pay out of pocket for this drug when they could have been using that money for better purposes,” Mandell says. “Now these families are experiencing the whiplash that happens when politics and untested theories get ahead of science.”