MDLinxDocs Call FDA Approval Without an RCT ‘Truly Bananas.’ What Precedent Does It Set for Evidence Standards?

The FDA approved leucovorin for cerebral folate deficiency based on 46 patients’ worth of case reports and real-world data, bypassing randomized controlled trials entirely. A separate political push to approve it for broad autism use drove a 71% spike in pediatric prescriptions before the agency narrowed the indication to a rare genetic subgroup.

Professional Impact

• The approval sets a regulatory precedent: real-world evidence and mechanistic rationale alone can now support FDA clearance, raising questions about evidentiary consistency across indications.
• The double standard is explicit: critics note vaccines required tens of thousands of trial participants while this approval rested on 27 treated patients.
• Most autism patients will not qualify: FOLR1 variants are required for the approved indication, meaning off-label prescribing for broader autism populations lacks regulatory or major society support.
• The American Academy of Pediatrics does not recommend routine leucovorin for autism, citing insufficient large-scale evidence.

Action Items

• Order FOLR1 genetic testing before considering leucovorin in any patient with suspected cerebral folate deficiency.
• Counsel parents that FDA approval applies only to a confirmed genetic subgroup, not autism broadly.
• Document clinical rationale carefully for any off-label leucovorin use given heightened regulatory and public scrutiny.
• Monitor forthcoming guidance on real-world evidence standards as this approval moves through post-market review.

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