The U.S. Food and Drug Administration (FDA) has approved leucovorin, a synthetic form of vitamin B9, as the first approved treatment for cerebral folate deficiency (CFD), a rare genetic neurological disorder. This approval follows earlier public statements by administration officials suggesting leucovorin's potential for broader autism spectrum disorder symptoms.
The FDA has clarified that there is insufficient data to establish the drug's efficacy for autism generally, while medical organizations, including the American Academy of Pediatrics, advise against its routine off-label prescription for the condition.
FDA Approves Leucovorin for Cerebral Folate Deficiency
The FDA's approval of leucovorin is specifically for adult and pediatric populations diagnosed with cerebral folate deficiency (CFD). This ultra-rare condition affects fewer than 1 in a million people and is characterized by low levels of folate (vitamin B9) in the brain, despite normal levels in the bloodstream.
Cerebral folate deficiency can manifest in children under two years old and lead to severe developmental delays, seizures, impaired muscle control, cognitive impairment, and other serious neurological complications.
Symptoms can include challenges with social communication, sensory processing, and repetitive behaviors.
The approval for CFD was based on a systematic review of published literature and patient case reports, rather than a randomized controlled clinical trial. FDA officials indicated that the data from leucovorin use in CFD patients demonstrated substantial treatment effects, justifying the focused approval.
Controversial Claims Spark Interest in Leucovorin for Autism
In September, statements from the Trump administration, including then-FDA Commissioner Marty Makary and President Donald Trump, promoted leucovorin as a potential therapy for autism symptoms. Dr. Makary suggested a potential FDA label change to allow its use for autism.
"Hundreds of thousands of kids, in my opinion, will benefit." — Dr. Marty Makary
This label change for autism has not occurred.
These claims generated significant public interest, leading to over 25,000 individuals joining a Facebook group focused on leucovorin for autism. Data published in The Lancet indicated a 71% increase in leucovorin prescriptions for children aged 5 to 17 in the 2.5 to 3 months following the administration's September announcements.
FDA Clarifies Stance Amid Medical Community Concerns
Following the specific approval for CFD, senior FDA officials clarified that there is insufficient data to establish leucovorin's broad efficacy for autism. The agency stated its review focused solely on the strongest evidence, which supported the drug's use only for patients with the specific genetic condition affecting brain folate levels. An FDA official noted the agency remains receptive to companies interested in further studying leucovorin for the autism population.
Medical groups, including the American Academy of Pediatrics, advise against the routine prescription of leucovorin for autistic children, even those with cerebral folate deficiency, citing insufficient scientific evidence to support its broad use.
Dr. Paul Offit, director of the vaccine education center at Children's Hospital of Philadelphia, views leucovorin's popularity as part of a recurring pattern of treatments promoted for autism without sufficient evidence.
Dr. Shafali Jeste, chair of pediatrics at the University of California, Los Angeles, does not prescribe leucovorin for autism, stating existing trials lack the rigorous methodology necessary for FDA approval for this indication.
Autism researchers, including Dr. Alycia Halladay of the Autism Science Foundation, have reiterated that leucovorin has not been shown to be safe or effective for the majority of individuals with autism. Dr. Michael Tranfaglia, medical director of the FRAXA Research Foundation, noted a similar pattern with leucovorin's initial use for Fragile X syndrome, where clinical trials later showed no benefit over placebo.
The Science Behind Leucovorin: A Complex Picture
The rationale for leucovorin's use relates to folate's role in brain development and the concept of cerebral folate deficiency. CFD can result from rare genetic mutations that impair folate transport into the cerebrospinal fluid, or from the immune system producing antibodies that block this transport.
A 2005 study in The New England Journal of Medicine involving 28 children with developmental disorders, including autism, all with low cerebrospinal fluid folate, found that leucovorin treatment elevated brain folate levels and appeared to alleviate symptoms in some participants. Twenty-five of these children tested positive for folate-blocking antibodies. Edward Quadros, a co-author, suggested leucovorin could use an "alternative pathway into the brain."
In 2018, another study, involving 48 autistic children with language impairment, reported enhanced communication skills in those receiving leucovorin over a 12-week period. The lead author, Dr. Richard Frye, acknowledged that dramatic responses were uncommon and that leucovorin is not a standalone cure, often requiring additional therapies. Dr. Frye's research has faced scrutiny, leading to his departure from academic institutions, and he now operates a private clinic.
Dr. Frye suggests that while a spinal tap confirms CFD, blood tests for folate-blocking antibodies may indicate risk, and he is currently conducting a randomized, controlled trial. However, groups like the Autism Science Foundation point out that non-autistic relatives often possess these same antibodies, suggesting they may not be a causal factor in autism. One study previously cited for leucovorin's use in autism, or one of two double-blinded, placebo-controlled trials, was later retracted due to errors.
Navigating Off-Label Prescribing and Access Challenges
Despite the lack of FDA approval for autism treatment, doctors can prescribe leucovorin off-label. Some private practitioners continue to prescribe the drug for autism. Dr. Richard Frye estimates approximately 80% of his autism patients receive a prescription. Naturopathic doctor Tiffany Banks also reports increased patient inquiries.
Accessing treatment from some of these private providers can involve significant costs:
Initial visits quoted at $1,896, plus deposits, and follow-ups at $948, often without insurance acceptance.
Clinicians face a dilemma, balancing parental demand with adherence to evidence-based practices. Some prescribe selectively in unique clinical scenarios, while others refuse due to the lack of robust evidence.
Supply Shortages and Safety Concerns Emerge
The increased demand for leucovorin, partly fueled by earlier administration statements, has led to drug shortages. The FDA permitted temporary imports of unapproved tablets from Spain sold in Canada and urged existing manufacturers to increase production to meet anticipated demand. GSK, which originally marketed the drug as Wellcovorin from 1983 to 1997, does not plan to relaunch or manufacture the product.
Reported side effects in individuals with autism considering the drug include irritability, aggression, and hyperactivity. Concerns exist regarding the drug's safety profile for children with autism, particularly in long-term use, and the lack of established dosing protocols.