FDA grants Ultragenyx a priority review voucher for its Sanfilippo gene therapy

The Food and Drug Administration has awarded a rare pediatric disease priority review voucher to Ultragenyx Pharmaceutical Inc., the maker of a newly approved gene therapy for a severe childhood brain disorder. A notice in the Federal Register on 6 October 2026 records that the agency issued the voucher to the sponsor of FAYUVI (rebisufligene etisparvovec-hopf), which it determined meets the statutory criteria for the award [s1].

FAYUVI was approved on 17 September 2026 [s1]. The agency describes it as an adeno-associated virus (AAV) vector-based gene therapy indicated for the treatment of the neurologic manifestations of mucopolysaccharidosis type IIIA — MPS IIIA, also known as Sanfilippo syndrome type A — in pediatric patients with preserved neurodevelopmental function [s1]. Sanfilippo type A is an inherited lysosomal storage disorder in which a missing enzyme lets cellular waste accumulate in the brain, producing progressive neurological decline in young children. The therapy is manufactured by Ultragenyx [s1].

What the voucher is

The award is made under section 529 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 360ff), which directs the FDA to grant priority review vouchers to sponsors of approved rare pediatric disease products that meet certain criteria [s1]. The statute also requires the agency to publish notice of each award, which is what the Federal Register document does [s1].

The voucher itself is the incentive. On the FDA's account of the programme, a priority review voucher can be redeemed to obtain priority review for a different product — a later application the holder wants the agency to assess on the faster of its two review tracks — and the sponsor may also transfer or sell the voucher to another sponsor [s2]. In practice that makes the voucher a freely tradable asset. A company that has no imminent use for faster review can sell it to one that does, and the prices paid have historically run into the tens of millions of dollars.

Why the programme exists

The logic of section 529 is to reward companies for bringing drugs to market in diseases that are too rare, and too commercially marginal, to attract development on their own. Sanfilippo type A is exactly that kind of target: a small paediatric population, no previously approved therapy aimed at the underlying neurological disease, and the long, expensive development path typical of a gene therapy. The voucher is Congress's attempt to tilt the economics by attaching a saleable benefit to an approval that might otherwise never repay its costs [s1][s2].

That design has drawn criticism as well as praise. Supporters argue it has demonstrably pulled investment into neglected childhood conditions, and that a saleable voucher is one of the few levers that reliably moves private capital toward diseases with tiny patient populations. Sceptics note that the reward is not tied to the price, availability or real-world benefit of the drug that earned it, and that the faster review a voucher buys for some later, unrelated product can shorten the FDA's scrutiny of that product. The programme has also repeatedly faced lapses and short-term reauthorisations in Congress, leaving its long-run future uncertain even as individual awards like this one continue to be issued.

What the notice settles, and what it does not

The Federal Register document is narrow. It confirms three things: that FAYUVI was approved on 17 September 2026, that the FDA has determined the product meets the criteria for a rare pediatric disease priority review voucher, and that the agency has issued that voucher to Ultragenyx [s1]. It is signed by the Deputy Commissioner for Policy, Legislation, and International Affairs [s1].

It does not say what the voucher will be used for, whether it will be sold, or at what price — those are commercial decisions for the company. Nor does the notice address the therapy's clinical evidence, its cost, or how many children in the United States might be eligible for it; the document is a record of a regulatory award, not a review of the drug. For families affected by Sanfilippo syndrome, the substantive news remains the September approval of a therapy aimed at the neurological course of the disease [s1]. The voucher is a separate, financial consequence of that approval — one designed to make the next rare-disease programme a little easier to fund.

Sources

• [s1] Issuance of Priority Review Voucher; Rare Pediatric Disease Product; FAYUVI (rebisufligene etisparvovec-hopf) — U.S. Food and Drug Administration (Federal Register), 6 October 2026.
• [s2] Rare Pediatric Disease (RPD) Designation and Priority Review Voucher Programs — U.S. Food and Drug Administration.