# FAYUVI (rebisufligene etisparvovec-hopf; UX111) PDUFA Event: Sanfilippo syndrome type A (mucopolysaccharidosis type IIIA)

Canonical URL: https://biopharmsignal.com/pdufa-calendar/RARE/ux111-sanfilippo-syndrome-type-a-review-2

Ticker: RARE

Company: Ultragenyx Pharmaceutical

Event date: 2026-09-19

Event type: FDA Decision

Stage: PDUFA

Result: Approved

Result date: 2026-09-17

Application type: BLA

Review cycle: 2

FDA granted full approval to FAYUVI. FDA granted standard full approval to FAYUVI, the first FDA-approved treatment for pediatric patients with mucopolysacch...

## Event Timeline

### September 17, 2026 — FDA granted full approval to FAYUVI

FDA granted standard full approval to FAYUVI, the first FDA-approved treatment for pediatric patients with mucopolysaccharidosis type IIIA (Sanfilippo syndrome type A). Ultragenyx received a Priority Review Voucher with the approval.

[FDA — Approval of FAYUVI for pediatric Sanfilippo syndrome type A](https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-pediatric-patients-sanfilippo-syndrome-type)

### April 2, 2026 — FDA accepted the BLA resubmission

FDA accepted the resubmitted UX111 BLA for review after Ultragenyx added information addressing the prior manufacturing-related observations.

[Ultragenyx — BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

### July 11, 2025 — FDA issued a Complete Response Letter in the first review cycle

The CRL cited chemistry, manufacturing and controls observations; Ultragenyx said FDA acknowledged the clinical data as robust and the biomarker evidence as supportive.

[Ultragenyx — UX111 Complete Response Letter](https://ir.ultragenyx.com/node/17891)

### December 2024 — Ultragenyx submitted the original BLA

Ultragenyx submitted the original BLA seeking accelerated approval, supported by data from the ongoing Transpher A study.

[Ultragenyx — 2024 results and UX111 regulatory update](https://ir.ultragenyx.com/news-releases/news-release-details/ultragenyx-reports-fourth-quarter-and-full-year-2024-financial)

## Regulatory Designations

- Priority Review FDA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- RMAT FDA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- Fast Track FDA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- Orphan Drug FDA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- Rare Pediatric Disease FDA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- PRIME EMA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

- Orphan Drug EMA: [Ultragenyx — UX111 BLA resubmission acceptance](https://ir.ultragenyx.com/node/18781)

## Related Pages

- RARE PDUFA calendar: https://biopharmsignal.com/pdufa-calendar/RARE.md

- RARE company profile: https://biopharmsignal.com/company/RARE.md

- PDUFA calendar: https://biopharmsignal.com/pdufa-calendar.md

## Related News

- 2026-10-07 — Ultragenyx Enters into Agreement to Sell Rare Pediatric Disease Priority Review Voucher for $210 Million: https://biopharmsignal.com/news/RARE/ultragenyx-enters-into-agreement-to-sell-rare-pediatric-disease-priority-review--e9651c18.md

- 2026-10-02 — Ultragenyx Announces Marketing Authorisation Application (MAA) Submission to the European Medicines Agency (EMA) for the First Investigational Gene Therapy for MPS IIIA (Sanfilippo Syndrome Type A): https://biopharmsignal.com/news/RARE/ultragenyx-announces-marketing-authorisation-application-maa-submission-to-the-e-1ad2a236.md

- 2026-09-17 — Ultragenyx Announces Approval of FAYUVI™ Gene Therapy, the First-Ever FDA-Approved Treatment for Sanfilippo Syndrome Type A (MPS IIIA): https://biopharmsignal.com/news/RARE/ultragenyx-announces-approval-of-fayuvi-gene-therapy-the-first-ever-fda-approved-f6fd354a.md

- 2026-09-02 — Ultragenyx Announces Phase 3 Aspire results in Angelman Syndrome: https://biopharmsignal.com/news/RARE/ultragenyx-announces-phase-3-aspire-results-in-angelman-syndrome-6f1182c3.md

- 2026-09-01 — Ultragenyx Announces the Publication of a Successful 96-Week Randomized, Placebo-Controlled Trial with Crossover Treatment of GENGLYCOS™ (also known as DTX401) AAV Gene Therapy in GSDIa in The Journal of Inherited Metabolic Disease: https://biopharmsignal.com/news/RARE/ultragenyx-announces-the-publication-of-a-successful-96-week-randomized-placebo--0f6d355a.md