Traders should monitor for any FDA communications, potential advisory committee meetings, or clinical updates ahead of the September 19, 2026 PDUFA date. Positive momentum in RARE stock is likely to continue unless new regulatory concerns emerge. Consider positioning for event-driven volatility as the action date approaches.
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Executive Summary
Ultragenyx Pharmaceutical Inc. announced that the FDA has accepted for review its resubmitted Biologics License Application (BLA) for UX111 (rebisufligene etisparvovec), an AAV9 gene therapy for Sanfilippo syndrome Type A (MPS IIIA), with a PDUFA action date of September 19, 2026. This marks a key regulatory milestone for a potential first-in-class therapy for a rare and severe pediatric neurodegenerative disease.
Key Facts
- FDA accepted resubmitted BLA for UX111 (rebisufligene etisparvovec) for accelerated approval
- Indication: Sanfilippo syndrome Type A (MPS IIIA), a rare pediatric neurodegenerative disorder
- PDUFA action date set for September 19, 2026
- Therapy is an AAV9 gene therapy, representing a potential one-time treatment
- Filing follows prior rejection, indicating successful resolution of prior FDA concerns
Financial Impact
Potential blockbuster revenue if approved; UX111 could achieve peak sales estimates in the hundreds of millions to over $1 billion annually, given the high unmet need and lack of approved therapies for MPS IIIA
Risk Factors
- FDA may ultimately deny approval despite acceptance for review
- Potential requirement for post-marketing studies or restrictive labeling
- Manufacturing or safety issues could delay or block approval
- Competition from other gene therapies or emerging modalities in rare neurogenetic diseases
Market Snapshot
Investment Themes
Documents Analyzed
This report is based on 3 SEC documents filed with EDGAR.
| Document | Accession Number |
|---|---|
| 8-K Filing (Primary) | 0001193125-26-139084 |
| Document: 0001193125-26-139084-index.html | 0001193125-26-139084 |
| Document: 0001193125-26-139084.txt | 0001193125-26-139084 |
Filters
| Type | Now | ||||
|---|---|---|---|---|---|
Sep 2, 2026 4w ago | 8-K | $14.85 $15.22 | ▼ −2.49% | ▼ −3.68% | $15.22 (−2.49%) |
Sep 1, 2026 4w ago | Press Release | $26.53 $15.03 | ▼ −43.35% | ▼ −43.02% | $15.22 (−42.63%) |
Aug 11, 2026 7w ago | 8-K | $26.80 $14.31 | ▼ −46.60% | ▼ −45.55% | $15.22 (−43.21%) |
Aug 4, 2026 8w ago | 8-K | $24.93 $26.53 | ▲ +6.42% | ▲ +7.02% | $15.22 (−38.95%) |
Aug 4, 2026 8w ago | Insider Cluster | $25.81 $25.81 | · 0.00% | ▲ +1.24% | $15.22 (−41.03%) |
Jun 15, 2026 15w ago | Insider Cluster | $24.85 $32.03 | ▲ +28.89% | ▲ +28.69% | $15.22 (−38.75%) |
Jun 11, 2026 16w ago | Institutional Cluster | $23.98 $34.61 | ▲ +44.33% | ▲ +42.44% | $15.22 (−36.53%) |
May 5, 2026 21w ago | Press Release | $25.93 $22.41 | ▲ +13.57% | ▲ +16.36% | $15.22 (+41.30%) |
May 1, 2026 22w ago | Insider Cluster | $24.77 $22.85 | ▼ −7.75% | ▼ −13.04% | $15.22 (−38.55%) |
Apr 2, 2026 26w ago | 8-K | $22.45 $24.69 | ▲ +9.98% | ▲ +0.10% | $15.22 (−32.20%) |
US Market Status
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