FDA Approves Leucovorin for Rare Brain Folate Disorder

The FDA has approved leucovorin for treating cerebral folate deficiency caused by FOLR1 gene mutations, a rare neurological disorder affecting folate transport into the brain.

The U.S. Food and Drug Administration has approved leucovorin, an active form of vitamin B9, for treating a rare genetic disorder that prevents folate from reaching the brain (1^✔ ✔Trusted Source
FDA Approves First Treatment for Patients with Cerebral Folate Transport Deficiency

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).
The approval applies specifically to patients with cerebral folate deficiency caused by mutations in the folate receptor 1 gene (FOLR1).

Regulators emphasize that current scientific evidence does not support the drug as a treatment for autism spectrum disorder.

What is Cerebral Folate Deficiency (CFD)

Cerebral Folate Deficiency (CFD) is a neurological condition in which folate transport into the central nervous system is impaired despite normal folate levels in the bloodstream.

Folate plays a key role in DNA synthesis, neurotransmitter production, and brain development. When folate cannot reach the brain adequately, patients may develop symptoms such as developmental delay, seizures, movement abnormalities, and speech difficulties.

Genetic Defects in FOLR1 Disrupt Folate Transport to the Brain

The FOLR1 gene produces folate receptor alpha, a protein responsible for transporting folate across the blood–brain barrier into the central nervous system. Mutations in this gene disrupt this transport process, leading to reduced levels of 5-methyltetrahydrofolate, the biologically active form of folate in cerebrospinal fluid (2^✔ ✔Trusted Source
Retraction Note: Efficacy of oral folinic acid supplementation in children with autism spectrum disorder: a randomized double-blind, placebo-controlled trial

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).

Although folate levels remain normal in blood circulation, the brain becomes functionally deficient. This deficiency can affect neuronal signaling, myelin formation, and cognitive development.

The disorder is extremely rare and is estimated to affect fewer than one in one million people worldwide. Fewer than 50 confirmed cases have been documented in medical literature.

Evidence Review Supporting FDA Approval

Because of the rarity of the condition, conducting large randomized controlled trials is difficult. Instead, the FDA based its approval on a systematic review of published case reports and mechanistic studies describing patients with genetically confirmed cerebral folate deficiency.

Researchers evaluated medical literature including 26 case reports and case series involving 46 patients with FOLR1-related cerebral folate deficiency. Among these patients, 27 individuals received oral leucovorin therapy alone.

Approximately 24 of the 27 patients, representing about 89 percent, showed meaningful clinical improvement. Improvements reported across studies included reduced seizure frequency, better motor coordination, and improvements in communication and behavior.

Leucovorin, also known as folinic acid, is a metabolically active form of folate. Unlike standard folic acid, it can bypass defective receptor pathways and enter the brain through alternative transport mechanisms, helping restore folate levels in the central nervous system.

Why Leucovorin Was Not Approved for Autism

Although leucovorin has been investigated as a possible therapy for autism spectrum disorder, regulators determined that the current evidence is insufficient to establish its effectiveness for autism.

Some studies suggest that a subgroup of children with autism may develop folate receptor autoantibodies, which may interfere with folate transport into the brain. However, available clinical trials have produced inconsistent results.

In addition, one of the largest randomized double-blind placebo-controlled studies examining folinic acid supplementation in children with autism was recently retracted due to data reporting errors. This development further weakened the evidence supporting the therapy for autism.

Because of these limitations, the FDA restricted approval strictly to patients with genetically confirmed FOLR1-related cerebral folate deficiency.

Clinical Significance for Rare Genetic Disorders

Although the approval applies to a very small patient population, it represents an important development for individuals affected by this rare disorder.

Leucovorin has been widely used for decades in oncology to reduce toxic effects of certain chemotherapy drugs. The new approval highlights how existing medications can be repurposed to treat rare genetic conditions when strong biological evidence supports their use.

Early diagnosis through genetic testing and measurement of folate levels in cerebrospinal fluid may help identify affected individuals and allow treatment to begin before neurological damage progresses.

Takeaway

Leucovorin has been approved as the first treatment for cerebral folate deficiency caused by mutations in the FOLR1 gene. Evidence from published case reports suggests that the drug can improve neurological symptoms in many affected patients. However, current research does not provide sufficient evidence to support leucovorin as a treatment for autism, highlighting the need for further well-designed clinical studies.

References:

1. FDA Approves First Treatment for Patients with Cerebral Folate Transport Deficiency – (https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-patients-cerebral-folate-transport-deficiency)
2. Retraction Note: Efficacy of oral folinic acid supplementation in children with autism spectrum disorder: a randomized double-blind, placebo-controlled trial – (https://doi.org/10.1007/s00431-026-06769-x)

Source-Medindia