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Ultragenyx (RARE) gets FDA review date for UX111 gene therapy on Sept. 19, 2026

Filing Impact
(Moderate)
Filing Sentiment
(Neutral)
Form Type
8-K

Rhea-AI Filing Summary

Ultragenyx Pharmaceutical Inc. reported that the U.S. FDA has accepted for review its resubmitted Biologics License Application seeking accelerated approval of UX111 (rebisufligene etisparvovec), an AAV9 gene therapy for Sanfilippo syndrome Type A (MPS IIIA). The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026 for this application.

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Insights

FDA acceptance of Ultragenyx’s UX111 BLA sets a clear review timeline.

The FDA has accepted Ultragenyx’s resubmitted Biologics License Application for UX111, an AAV9 gene therapy targeting Sanfilippo syndrome Type A. Acceptance moves UX111 formally into regulatory review and keeps open the possibility of accelerated approval.

The agency established a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026, providing a defined timing marker for a potential decision. The company highlights multiple risks, including sufficiency of clinical, biomarker and long‑term follow‑up data, manufacturing readiness at internal and third‑party sites, and potential safety or tolerability issues.

The outcome will depend on FDA’s assessment of the resubmitted data package and any regulatory inspections referenced in the text. Future company disclosures around UX111’s review status and manufacturing capabilities are likely to clarify how these risks evolve as the September 19, 2026 PDUFA date approaches.

Item 8.01 Other Events Other
Voluntary disclosure of events the company deems important to shareholders but not covered by other items.
PDUFA action date September 19, 2026 FDA review timeline for UX111 Biologics License Application
Biologics License Application regulatory
"has accepted for review the Company’s resubmitted Biologics License Application seeking accelerated approval"
A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.
accelerated approval regulatory
"resubmitted Biologics License Application seeking accelerated approval for UX111"
Accelerated approval is a process that allows new medical treatments to be approved more quickly than usual if they address serious or life-threatening conditions and show promising early results. For investors, it signals that a treatment may reach the market sooner, potentially boosting a company's prospects, but it also involves some uncertainty since full evidence of effectiveness is still being gathered.
AAV9 gene therapy medical
"UX111 (rebisufligene etisparvovec) AAV9 gene therapy as a treatment"
AAV9 gene therapy uses a harmless, naturally occurring virus (AAV9) as a delivery vehicle to carry a working copy of a gene into patients’ cells, often targeting muscle and nervous tissue. Think of it as a microscopic mail carrier delivering an instruction manual so broken cells can produce a missing protein; for investors, it matters because such one-time treatments can command high prices, carry big development and regulatory risks, and can significantly affect a developer’s future revenue and valuation.
Sanfilippo syndrome Type A (MPS IIIA) medical
"as a treatment for patients with Sanfilippo syndrome Type A (MPS IIIA)"
Prescription Drug User Fee Act (PDUFA) regulatory
"The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026."
The Prescription Drug User Fee Act (PDUFA) is a law that allows drug companies to pay fees to the government to help speed up the review process for new medicines. This funding aims to ensure that important drugs reach patients faster, which can influence a company's ability to bring products to market efficiently. For investors, PDUFA-related decisions can impact drug approval timelines and company performance.
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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

 

FORM 8-K

 

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 02, 2026

 

 

Ultragenyx Pharmaceutical Inc.

(Exact name of Registrant as Specified in Its Charter)

 

 

Delaware

001-36276

27-2546083

(State or Other Jurisdiction
of Incorporation)

(Commission File Number)

(IRS Employer
Identification No.)

 

 

 

 

 

60 Leveroni Court

 

Novato, California

 

94949

(Address of Principal Executive Offices)

 

(Zip Code)

 

Registrant’s Telephone Number, Including Area Code: 415 483-8800

 

 

(Former Name or Former Address, if Changed Since Last Report)

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of each class

 

Trading
Symbol(s)

 


Name of each exchange on which registered

Common Stock, $0.001 par value

 

RARE

 

Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

 

 


 

Item 8.01 Other Events

 

On April 2, 2026, Ultragenyx Pharmaceutical Inc. (the “Company”) issued a press release announcing that the U.S. Food and Drug Administration (the “FDA”) has accepted for review the Company’s resubmitted Biologics License Application seeking accelerated approval for UX111 (rebisufligene etisparvovec) AAV9 gene therapy as a treatment for patients with Sanfilippo syndrome Type A (MPS IIIA). The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026.

 

Cautionary Note Regarding Forward-Looking Statements

 

This Current Report on Form 8‑K contains forward‑looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may be identified by the use of words such as, but not limited to, “anticipates,” “expects,” “plans,” “continues,” “will,” “may,” “potential,” or other similar terms or expressions that concern the Company’s expectations, plans, objectives, and intentions.

 

Forward‑looking statements include, without limitation, statements related to the Company’s expectations and projections, the development, regulatory status, review, timing and potential approval of UX111 (rebisufligene etisparvovec), including the anticipated PDUFA action date, the potential for accelerated approval, the outcome of the FDA’s review of the resubmitted Biologics License Application (BLA), the timing and outcome of any regulatory inspections, the sufficiency of clinical, biomarker and longterm followup data to support regulatory approval, expectations regarding the safety, tolerability and durability of UX111, manufacturing readiness and capabilities, including at thirdparty and companyowned manufacturing facilities, and the potential availability and commercial launch of UX111. Such forwardlooking statements involve substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied by the forwardlooking statements. These risks and uncertainties include, among others, the uncertainty and unpredictability inherent in clinical drug development and the regulatory review and approval process; the possibility that the FDA may not accept or agree that the submitted data are sufficient to support accelerated or full approval of UX111; the risk that additional data, analyses or studies may be required; the timing, scope and outcome of regulatory inspections; risks related to the manufacture of UX111, including reliance on thirdparty manufacturers and the Company’s limited experience operating its own manufacturing facilities; the ability of the Company and its manufacturing partners to comply with regulatory requirements; potential safety or tolerability issues; competition from other therapies or products; smaller than anticipated market opportunities; and other risks related to the Company’s ability to fund operations, future operating results and financial performance.

 

The Company undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the business of the Company in general, see the Company's Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 18, 2026, and its subsequent periodic reports filed with the SEC.

 

 


 

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

 

 

 

Ultragenyx Pharmaceutical Inc.

 

 

 

 

Date:

April 2, 2026

By:

/s/ Howard Horn

 

 

 

Howard Horn
Executive Vice President, Chief Financial Officer, Corporate Strategy

 

 


FAQ

What did Ultragenyx (RARE) announce regarding UX111 in this 8-K?

Ultragenyx announced that the FDA accepted for review its resubmitted Biologics License Application for UX111, an AAV9 gene therapy for Sanfilippo syndrome Type A, under a potential accelerated approval pathway, moving the program into a formal regulatory review phase.

What is the PDUFA action date for Ultragenyx (RARE) UX111 application?

The FDA set a Prescription Drug User Fee Act (PDUFA) action date of September 19, 2026 for Ultragenyx’s resubmitted Biologics License Application for UX111, establishing a target date for a regulatory decision on the potential accelerated approval.

What indication is Ultragenyx (RARE) seeking to treat with UX111?

Ultragenyx is seeking approval of UX111 (rebisufligene etisparvovec), an AAV9 gene therapy, as a treatment for patients with Sanfilippo syndrome Type A (MPS IIIA), a specific subtype of mucopolysaccharidosis involving progressive neurological decline.

Is Ultragenyx’s UX111 filing with the FDA for accelerated approval?

Yes. The company stated that its resubmitted Biologics License Application for UX111 seeks accelerated approval, meaning the FDA could base its decision on surrogate measures reasonably likely to predict clinical benefit rather than waiting for full clinical outcome data.

What key risks did Ultragenyx (RARE) highlight about UX111’s FDA review?

Ultragenyx noted uncertainties around the regulatory review process, including whether data will support accelerated or full approval, potential requests for additional studies, manufacturing and regulatory inspection risks, possible safety or tolerability issues, and competition or smaller-than-expected market opportunities for UX111.

Filing Exhibits & Attachments

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