The Trump administration last September promoted leucovorin as a promising treatment for autism, with FDA Commissioner Marty Makary claiming a "growing body of evidence" suggested it could help 20-50% of children with the condition. Makary made bold assertions at a White House press event, suggesting "hundreds of thousands of kids" would benefit from the generic drug's use for autism.

The administration's advocacy had immediate impact. A study published in The Lancet found that outpatient prescriptions of leucovorin for children ages 5-17 jumped 71% in the three months after the promotion. Despite this surge in usage, the FDA announced today it had approved leucovorin only for treating a rare genetic condition, not autism.

Senior FDA officials told the Associated Press they found insufficient evidence for expanding leucovorin's use to autism treatment. The agency limited approval to cerebral folate deficiency in adults caused by a specific genetic mutation. The decision contradicts the Trump administration's earlier claims about the drug's effectiveness for autism.