The Food and Drug Administration on Tuesday announced a new approved use for the drug leucovorin, a synthetic form of vitamin B9 that the Trump administration has touted as a treatment for autism symptoms.
But the new approval is not for autism — it’s for cerebral folate deficiency, a rare neurological condition characterized by low levels of vitamin B9 in the brain.
Contrary to the messages President Donald Trump and FDA Commissioner Marty Makary gave in September when they announced a plan to relabel the drug, a senior FDA official said Monday that there is not enough data to support leucovorin’s use as an autism treatment.
“We don’t have sufficient data to say that we could establish efficacy for autism more broadly,” the official said. “It’ll be up to patients to talk with their physicians to see if that might be right for them.”
Leucovorin is used mainly to help mitigate the side effects of chemotherapy or enhance its effectiveness for cancer patients. But at a briefing on Sept. 22, Makary said the FDA was taking steps to change the drug’s label “so that it can be available to children with autism,” adding that “hundreds of thousands of kids, in my opinion, will benefit.”
Trump said at the time that the updated drug label would “reflect potential benefits in reducing some autism symptoms.”
“This gives hope to the many parents with autistic children that it may be possible to improve their lives,” he said.
Many experts who research or treat autism questioned that rhetoric, saying the medication needed further study before it was rolled out to patients with autism.
Alycia Halladay, chief science officer at the Autism Science Foundation, said the FDA’s announcement Tuesday is “1,000% different” from the administration’s rhetoric in September.
The actual change the FDA proposed nearly six months ago did not say the medication would be approved to treat autism. Rather, the agency said it was initiating the approval of leucovorin tablets for patients with cerebral folate deficiency and described an overlap between the symptoms of that condition and autism, such as challenges with social communication, sensory processing and repetitive behaviors.
One in 1 million people are estimated to have cerebral folate deficiency, and although some researchers suspect the condition might be associated with autism, it is thought to affect only a small minority of autism patients.
Even though leucovorin is not approved to treat autism, doctors can prescribe it off-label. Some were doing so before Trump’s comments in September, based on the findings of a handful of small trials conducted mostly outside the U.S. The results of one such trial, published in the European Journal of Pediatrics, were retracted in January after the authors identified several errors in their data.
In the 2½ months following Trump’s announcement in September, leucovorin prescriptions for children rose 71%, according to data published last week in the medical journal The Lancet.
“The bell has been rung, and we’ve already seen through the data that prescriptions for leucovorin have skyrocketed,” Halladay said. “I don’t see that changing with this announcement that it’s only approved for cerebral folate deficiency.”
David Mandell, a psychiatry professor at the University of Pennsylvania, said the FDA’s announcement this week amounts to mixed messaging, given the Trump administration’s description of leucovorin in September.
“This is just terrible for families — this back-and-forth about what treats autism, what doesn’t treat autism, what causes autism, what doesn’t cause it,” he said. “Families deserve better than that. They deserve more careful science. They deserve more accurate information.”
Nonetheless, Mandell said he was “relieved” that the FDA is not approving leucovorin for autism patients, “given the very weak data and my understanding that the current trials that are underway are not coming back promising for autism.”