FDA approves leucovorin for rare genetic condition and not for autism

The FDA refuses to approve the drug that Trump has touted as a treatment for autism

By Claire Cameron edited by Clara Moskowitz

The US 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 deficiency in the brain. The decision comes just months after US President Donald Trump, Health and Human Services Secretary Robert F. Kennedy, Jr., and FDA Director Marty Makary hailed the drug as a treatment for autism. After a scientific review, the FDA, which falls under Kennedy’s oversight, decided there was not enough data to support the drug’s use.

“Autism is not caused by folate deficiency,” says David Mandell, a professor of psychiatry at the University of Pennsylvania who studies autism. “The data suggesting that is outdated and weak.”

Leucovorin is usually 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 the use of cerebral folate deficiency — a rare genetic condition that may affect fewer than one in a million people, although its true prevalence is unknown. It is caused by a mutation on FOLR1 the gene and can cause some similar symptoms to autism, such as communication problems. But autism is a separate condition, and a broad diagnosis. Although it can sometimes be linked to specific genetic factors, many researchers believe that autism has no single cause.

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“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 completely different neurological disorder, and most importantly FOLR1 the gene has never been associated with autism,” she says.

The FDA’s decision is welcome, says Mandell, but it will not reverse the interest the Trump administration has shown in using the drug to treat autism. “Pandora’s box is already open,” he adds. Prescriptions for off-label leucovorin — that is, to use the drug to treat a condition for which it is not approved — have skyrocketed among children by 71 percent after officials touted its potential benefits for autism. Tager-Flusberg says 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 could cure autism led many families to pay for this drug when they could have put the money to better use,” says Mandell. “Now these families are experiencing the whiplash that happens when politics and unproven theories take precedence over science.”

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