Leucovorin’s FDA nod is not a cure, it’s a controversial lever. Personally, I think the agency’s decision to expand approval for a decades-old vitamin to a rare brain disorder signals both a pragmatic rush to options for desperate families and a troubling pattern: using limited or indirect evidence to broaden a patient pool without the full guardrails of robust trials. What makes this particularly fascinating is how the same molecule can sit at opposite ends of the medical map—a supportive agent in chemotherapy shielding against toxicity, and now a potential key for cerebral folate deficiency and, narrowly, autism-related symptoms.
