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The FDA will approve leucovorin, a medication used in cancer treatments to counter the harmful side effects of other drugs, as an autism treatment after it showed promise in some patients, the Trump administration announced Monday — but some scientists caution that more research is needed.
In a statement, the U.S. Food and Drug Administration (FDA) said leucovorin will be approved for autistic people with cerebral folate deficiency (CFD), a neurological condition that affects the transport of folate — an essential vitamin for brain health — into the brain. Leucovorin is a type of folate called folinic acid.
CFD patients have “developmental delays with autistic features,” including seizures, problems with movement and coordination, repetitive behaviors, and difficulties with communication and sensory processing, according to the FDA.
The Washington Post reported Sunday that early clinical trials involving the administration of leucovorin to autistic children have shown “remarkable improvements” in those children’s “ability to speak and understand others.” The findings “have sent ripples through the scientific community,” according to the Post.
Research scientist and author James Lyons-Weiler, Ph.D., welcomed the news.
“The coordinated research response on leucovorin and the 180-degree change in focus from genes only to common environmental exposures as fundamental causes of autism and neurodevelopmental disorders are unprecedented,” he said.
But some researchers said leucovorin is associated with adverse events and deaths, and that more research on its safety is needed.
Writing on Substack, Albert Benavides, founder of VAERSAware.com, said the FDA Adverse Event Reporting System (FAERS) shows that a significant number of adverse event reports for leucovorin are death reports.
As of today, 24,496 adverse events related to leucovorin have been filed with FAERS. Of these, 23,784 were classified as serious and 4,189 — or 17.6% — were death reports.
Leucovorin first FDA-recognized treatment for autism
At Monday’s White House event announcing the new treatment and other autism-related developments, U.S. Health Secretary Robert F. Kennedy Jr. said studies have demonstrated leucovorin’s effectiveness in autistic children.
“Peer-reviewed literature has documented that up to 60% of folate-deficient children with ASD [autism spectrum disorder] can have improved verbal communications,” Kennedy said.
Speaking at the event, FDA Commissioner Marty Makary said leucovorin is “the first FDA-recognized treatment pathway for autism,” which “wouldn’t have happened without the leadership of the president and the secretary.”
Monday’s announcement came just months after the Centers for Disease Control and Prevention (CDC) revealed data showing that an estimated 1 in 31 (3.22%) 8-year-old children had an ASD diagnosis in 2022 — up from 1 in 36 (2.8%) in 2020 and 1 in 1,000 in the 1990s.
President Donald Trump, who kicked off Monday’s press conference, referenced these figures, pointing out the sharp increase from decades ago, when only 1 in 10,000 children had autism.
It’s a ‘treatment, not a cure’
In a statement, the U.S. Department of Health and Human Services (HHS) clarified that “leucovorin is not a cure for ASD and may only lead to improvements in speech-related deficits for a subset of children with ASD.”
“Furthermore, this treatment must be administered under close medical supervision and in conjunction with other non-pharmacological approaches for children with ASD (e.g., behavioral therapy),” HHS stated.
Karl Jablonowski, Ph.D., senior research scientist at Children’s Health Defense, said that while leucovorin “is a treatment, not a cure,” it is vital for human health.
“Our cells require folate metabolism for a variety of necessary functions, including tissue growth and maintenance and, when needed, DNA repair,” he said.
According to the FDA, the agency conducted a systematic analysis of literature published between 2009-2024, finding that “leucovorin calcium can help individuals suffering from CFD.”
Studies on folate and autism date back to early 2000s
The Post reported Monday that research into the relationship between folate and autism “goes back to the early 2000s, when scientists started exploring whether folic acid supplements taken during pregnancy — recommended since 1992 — could affect a child’s brain development.”
A 2004 study found that some children with autism-like symptoms had a condition that blocked the transport of folate into the brain.
According to the Post, Dr. Richard E. Frye, a child neurologist and director of research at the Rossignol Medical Center in Phoenix, estimates that up to 70% of people with autism may have a gene variation that leads to this condition.
Frye conducted several studies that were partially funded by the National Institutes of Health (NIH) and the U.S. Department of Defense. In one study of 44 children, 67% of those who took leucovorin saw improvements in their language abilities.
According to the Post, Frye and other researchers met last month with NIH Director Jay Bhattacharya, who showed interest in their research and placed them in contact with FDA officials “to discuss how to speed up” leucovorin’s approval as an autism treatment.
“There are many people who think autism is not treatable,” Frye told the Post. “It’s a ‘win’ to show that’s not the case.”
Frye, who is also chief scientific officer of the Autism Discovery & Treatment Foundation, told The Defender that several clinical studies have demonstrated promising results for leucovorin in autistic children.
“At this time, there are now five blinded controlled studies on leucovorin and autism across five countries. In total, there are about 250 children who have been included in these trials, and all trials have been positive,” Frye said.
Frye said leucovorin has proven to be safe, though further research into its use is needed:
“There are definitely some limitations to these trials as we still need to know the exact dose that is most effective, and which children would benefit the most from the treatment.
“However, leucovorin is very safe and can be highly effective in some patients, so its use in consultation with a physician who has experience is reasonable for a patient with autism who is not making gains with standard therapy.”
Speaking on CNBC’s “Squawk Box” on Monday, former FDA Commissioner Scott Gottlieb said leucovorin’s efficacy is still inconclusive.
“I don’t think you should go out and use it right now based on the body of evidence that exists, but it’s certainly worthy of further exploration,” he said.
Frye said it has been difficult to perform larger-scale studies involving leucovorin.
“Since leucovorin is a generic medication, it is very difficult to get interest in doing large clinical studies with any type of outside investment,” he said.
‘Tough’ trials needed on link between leucovorin and acetaminophen
The FDA also announced on Monday that it will immediately add notices to Tylenol and other products that contain acetaminophen, warning pregnant women of a possible link between acetaminophen and autism. The FDA will also advise physicians and the public about the risks.
According to William Parker, Ph.D., CEO of WPLab and a researcher who has studied acetaminophen risks for the last 10 years, more studies are needed on the potential for leucovorin to protect children from injuries stemming from acetaminophen.
Parker told The Defender:
“We know that among the many, many things that can make acetaminophen more dangerous to a fetus or a newborn, or a small child under the age of 6, is problems with folate.
“Folate is really important for the metabolism of acetaminophen, so it’s all tied together in a very real sense. I don’t think anyone has ever looked at, ‘would this drug sort of protect children from injury from acetaminophen?’”
Parker said such studies would be difficult to perform.
“You’d have to do a clinical trial on that with and without exposure to the drug and acetaminophen, and you’d have to follow kids for five or six years,” he said. “That would be a tough experiment to do.”
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‘I don’t know if leucovorin is contaminated with aluminum’
British chemist Christopher Exley, Ph.D., who has studied the potential link between aluminum exposure and the onset of autism, also said further research is needed before declaring that leucovorin is an effective treatment for autism.
In some countries, including the U.K., folate is added to flour because of the belief that folate deficiency “leads to neurodevelopmental conditions such as autism,” Exley said.
However, Exley said his research has shown that folic acid supplements sold over the counter “were heavily contaminated with aluminum,” adding that pregnant women “are encouraged to take folate supplements.” He said:
“I don’t know if leucovorin is contaminated with aluminium, but I suspect that it is and even if it was not, I cannot think of any reason why it would help to prevent the brain damage we see in severe autism.
“It may have benefits with respect to less significant neurodevelopmental effects but it will not and cannot protect against aluminium-induced brain damage.”
Related articles in The Defender- ‘Uncompromising and Relentless’: HHS to Study All Possible Causes of Autism, Including Vaccines
- HHS Will Link Autism to Tylenol Use During Pregnancy, Wall Street Journal Reports
- Breaking: HHS to Announce ‘Certain Interventions’ Behind Rising Autism Rates, RFK Jr. Tells Trump Cabinet
- ‘Parents Have Waited for 30 Years’: NIH to Study Causes of Autism
- CDC Will Study Possible Link Between Vaccines and Autism, Pledges to ‘Leave No Stone Unturned’
