The FDA has decided not to approve a $2.50 pill once praised as a potential breakthrough treatment for autism, even though it was previously touted as promising for many children.

On Tuesday, the FDA gave the green light to leucovorin, a high-dose B vitamin derived from folic acid, specifically for the treatment of cerebral folate deficiency (CFD). This condition impairs the brain’s ability to absorb folate, a natural form of folic acid found in foods such as leafy greens.

Recent studies suggest that approximately 75% of individuals with autism may have CFD, which could potentially contribute to the speech and behavioral challenges often associated with autism.

Despite this, the FDA did not extend approval of leucovorin for autism treatment. This decision comes after earlier comments from FDA Commissioner Dr. Marty Makary, Health and Human Services Secretary Robert F. Kennedy Jr., and former President Donald Trump, who all suggested in September that leucovorin might benefit children with autism.

Kennedy previously described the treatment as an “exciting therapy” that could potentially assist a significant number of children affected by autism.

During the same briefing, Trump made controversial claims suggesting Tylenol might contribute to autism and advised parents to be cautious about administering too many vaccines to their children.

Trump said changing the label on leucovorin, traditionally given to cancer patients to lessen the effects of chemotherapy, for autism ‘gives hope to the many parents with autistic children that it may be possible to improve their lives.’

The FDA’s move comes after the American Academy of Pediatrics (AAP), America’s leading pediatrician group, said in October that it did not recommend routine use of leucovorin for autistic children due to ‘very limited evidence’ that the benefits of outweigh potential risks, as well as unclear data on dosages for children.

The FDA on Tuesday approved leucovorin (pictured in the above file image) for cerebral folate deficiency but not for autism 

The FDA said about its leucovorin approval for CFD: ‘This action reflects the agency’s commitment to accelerating cures and expanding treatment options including for patients with serious and unmet needs. 

‘Leucovorin is the first treatment for the rare genetic condition of cerebral folate deficiency.’

Leucovorin is derived from folic acid (also known as Vitamin B9), a vital nutrient that helps synthesize DNA and replicates and repairs cells throughout the body. 

Its naturally occurring form, folate, is found in foods such as leafy green vegetables, beans and lentils.

Folic acid is a precursor to DNA and RNA, which are needed to help replicate a cell’s genome – a set of instructions that help cells function properly. This is why most prenatal vitamins contain folic acid.

Research on leucovorin dates back to the early 2000s, during which scientists Dr Vincent Ramaekers of the University of Liege in Belgium and Dr Edward Quadros of SUNY Downstate University of New York, took blood and spinal fluid samples from autistic children and found that while they had normal folic acid levels in their blood, there was much less in their cerebrospinal fluid, which protects the brain and spinal cord.

This suggested that something was blocking folate’s absorption by the brain.

FDA commissioner Dr Marty Makary (pictured above with President Trump and Robert F Kennedy Jr last year) said: ‘Today’s approval represents a significant milestone for patients living with cerebral folate transport deficiency due to the FOLR1 variant, a rare genetic condition that has had no FDA-approved treatment options until today.’

The researchers also found 75 percent of autistic children had autoantibodies in their blood, a type that mistakenly targets and attacks the body’s tissues and organs.

These autoantibodies are known to block a protein called folate receptor alpha, a protein that transports folic acid from the blood into the brain and placenta.

Research suggests that leucovorin may clear chemical blockages in the brains of autistic children, and this contributes to improving their language skills

But unlike other forms of folate, such as those in vitamin supplements, leucovorin is able to cross the blood-brain barrier – a semi-permeable layer lining the inner surface of blood vessels in the brain that protects it from potentially damaging substances in the blood. 

This means it can penetrate the brain and have a direct effect.

The FDA’s move to approve leucovorin for CFD was based on an analysis of data from about 40 cases, showing improvements in behaviors such as speech in autistic children taking leucovorin. 

‘Today’s approval represents a significant milestone for patients living with cerebral folate transport deficiency due to the FOLR1 variant, a rare genetic condition that has had no FDA-approved treatment options until today,’ Makary said. 

He added: ‘This action may benefit some individuals with FOLR1- related cerebral folate transport deficiency who have developmental delays with autistic features.’

Dr Richard Frye, a pediatric neurologist at Rossignol Medical Center in Arizona, has seen non-verbal autistic children begin speaking in full sentences in a matter of weeks on leucovorin, as well as display less aggression and anxiety. 

Daily Mail previously spoke with the parents of several children treated by Dr Frye who were prescribed leucovorin. One boy from Missouri was almost completely non-verbal before taking leucovorin. After two weeks, he told his father he loved him for the first time.

Another 12-year-old boy went from only speaking one or two works at a time to being able to tell his family in full sentences what was bothering him about six weeks after starting one of Dr Frye’s trials on leucovorin.

Dr Richard Frye, a pediatric neurologist at Rossignol Medical Center in Arizona, previously told the Daily Mail that leucovorin ‘is one of the safest drugs available’ for autistic children

Nathaniel Schumann (left), 12, would only speak two to three words at a time before starting leucovorin. Now, he can speak in full sentences. And 10-year-old Meghan Dumesnil (right) has seen ‘dramatic’ speech improvements since starting the drug

‘Leucovorin is one of the safest drugs available,’ Dr Frye previously told the Daily Mail. ‘Leucovorin was approved for use to protect the body from chemotherapy side effects in the 50s. Thus, we have over 70 years of experience in regards to its safety.’

He noted that because folate in leucovorin is water soluble, excess levels are excreted out of the body through urine, ‘the body’s natural safety mechanism,’ and synthetic folate like this does not have an upper safety limit. 

He compared this to other medications used for autism, risperidone (Risperdal) and aripiprazole (Abilify), which are both antipsychotics. 

‘These are known to cause weight gain, diabetes and tardive dyskinesia [a neurological disorder that causes involuntary face and jaw movements],’ Dr Frye said. 

In addition to the 40 case studies cited by the FDA, Dr Frye also pointed toward five involving more than 250 children, which ‘is comparable to the number of children used in the registration studies to gain FDA approval for the currently approved medication for autism.’

‘In conclusion, leucovorin is much safer than the current medications approved for autism and more effective,’ he added.  

But he has emphasized that leucovorin is not a cure for autism, and it often needs to be used alongside other therapies and medications such as risperidone and aripiprazole.