BASEL, Switzerland, Nov. 06, 2026 (GLOBE NEWSWIRE) — Ultragenyx (NASDAQ:RARE), a biopharmaceutical company focused on the development and commercialisation of novel therapies for rare and ultra-rare genetic diseases, today announced that the UK Medicines and Healthcare products Regulatory Agency (MHRA) accepted on 28th October 2026 the Company’s Marketing Authorisation Application (MAA) for rebisufligene etisparvovec (also known as rebi-vec or UX111), an investigational gene therapy for the treatment of mucopolysaccharidosis Type IIIA (MPS IIIA), also known as Sanfilippo syndrome Type A.
Sanfilippo syndrome Type A is a rare, progressive, inherited disorder associated with severe neurological impairment and significant unmet medical need. Currently, treatment options remain limited for affected children and their families.
MHRA acceptance confirms that the application is sufficiently complete for the Agency to begin its formal scientific review of UX111, which remains investigational in the UK. There can be no assurance that marketing authorisation will ultimately be granted.
“The acceptance of our application by the MHRA marks an important regulatory milestone in the ongoing review process for this investigational therapy,” said Jane Cooper, Senior Vice President and Region Head for Europe, Middle East and Africa at Ultragenyx. “We recognise the profound unmet need within the Sanfilippo syndrome Type A community and are working with urgency to advance our regulatory strategy. To enable sustainable access on the NHS for eligible children, we have agreed to schedule the NICE evaluation to align with the Marketing Authorisation Application review with the ambition to receive a NICE decision as close as possible to a potential regulatory approval”.
Ultragenyx also announced last month the start of the European Medicines Agency (EMA) Marketing Authorisation Application review.
The MHRA is responsible for assessing the product’s quality, safety and efficacy for regulatory authorisation. The National Institute for Health and Care Excellence (NICE) is responsible for appraising the clinical and cost-effectiveness to inform NHS funding decisions in England. The NICE Prioritisation Board previously routed the treatment to the Highly Specialised Technology programme (HST) after agreeing that it meets all four of the criteria of the HST framework, including that it is an innovation to treat an ultra-rare and debilitating condition.
About Sanfilippo Syndrome Type A
Sanfilippo syndrome Type A is an ultra-rare, fatal lysosomal storage disease that primarily affects the brain and is marked by rapid, progressive neurodegeneration beginning in early childhood. Children with Sanfilippo syndrome Type A typically experience progressive global developmental delay, followed by the loss of cognitive, language, and motor function, ultimately leading to early death. Sanfilippo syndrome Type A is estimated to affect approximately 3,000 to 5,000 patients in commercially accessible geographies, with a median life expectancy of 15 years. The disease is caused by a deficiency of the sulfamidase (SGSH) enzyme, which results in the accumulation of heparan sulfate substrate in cells and progressive damage to the central nervous system.
About rebisufligene etisparvovec
Rebisufligene etisparvovec is a single-dose intravenous AAV9 gene therapy designed to deliver a functional copy of the deficient enzyme gene that can express and replace the SGSH enzyme. Ultragenyx received FDA approval for rebisufligene etisparvovec on September 17th, 2026. UX111 remains investigational in the UK and has not received MHRA marketing authorisation.
About Ultragenyx
Ultragenyx Pharmaceutical is a biopharmaceutical company committed to bringing novel therapies to patients for the treatment of serious rare and ultra-rare genetic diseases. The company has built a diverse portfolio of approved medicines and treatment candidates aimed at addressing diseases with high unmet medical need and clear biology, for which there are typically no approved therapies treating the underlying disease.
Forward-Looking Statements and Ultragenyx’s Use of Digital Media
Except for the historical information contained herein, this press release contains forward-looking statements, including statements regarding the MHRA review of the Marketing Authorisation Application for rebisufligene etisparvovec (UX111); the potential timing and outcome of that review and any MRHA decision; the potential safety, efficacy and benefits of UX111; the timing and outcome of the evaluation by the National Institute for Health and Care Excellence (NICE) and the potential timing of a NICE decision relative to any MHRA decision; potential access to UX111 through the NHS; the European Medicines Agency (EMA) review of the Marketing Authorisation Application for UX111 and the potential timing and outcome of that review; and Ultragenyx’s global regulatory strategy and plans for regulatory engagement and potential expansion in other geographies, including discussions with the Saudi Food and Drug Authority (SFDA). These statements are forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied. Such risks and uncertainties include, among others, the possibility that the MHRA or other health authorities request additional data, studies or manufacturing information, delay review, or decline to grant marketing authorisation or other approvals; that clinical data do not establish the safety and efficacy required for approval; that manufacturing, quality or supply issues arise; that NICE does not recommend UX111 for NHS funding, or that the timing or outcome of the NICE evaluation or of other pricing and reimbursement processes delays or limits patient access; that the EMA does not grant marketing authorisation on the expected timeline or at all; that FDA approval of UX111 is not predictive of the outcome of the MHRA, EMA or other regulatory reviews; that new safety information emerges from commercial use or ongoing studies of UX111; and that Ultragenyx’s estimates of the patient population prove inaccurate.
For further information about risks and uncertainties affecting Ultragenyx, see its Quarterly Report on Form 10-Q filed on November 4, 2026, and subsequent periodic reports filed with the SEC. Ultragenyx undertakes no obligation to update or revise these forward-looking statements, except as required by law.
In addition to its SEC filings, press releases and public conference calls, Ultragenyx uses its investor relations website and social media outlets to publish important information about the company, including information that may be deemed material to investors, and to comply with its disclosure obligations under Regulation FD. Financial and other information about Ultragenyx is routinely posted and is accessible on Ultragenyx’s Investor Relations website (https://ir.ultragenyx.com/) and LinkedIn website (https://www.linkedin.com/company/ultragenyx-pharmaceutical-inc-/).
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