Sanfilippo Type A Gene Therapy Enters European Review as EMA Confirms Application Completeness

For families of children with Sanfilippo syndrome type A, the disease takes away language, cognitive, and motor skills gradually acquired by their children. A treatment that targets the missing gene has now moved one step closer to marketing authorization in Europe: on October 2, Ultragenyx announced that the European Medicines Agency (EMA) had confirmed that the marketing authorization application for rebisufligene etisparvovec was sufficiently complete to begin formal scientific review.

This development has clear limits. Both Ultragenyx’s announcement and RTTNews’s report state that confirmation of the application’s completeness does not constitute approval, nor does it mean that EMA has made a judgment on the therapy’s safety or efficacy. For patients, it means the application has entered the next stage, with some distance still to go before the therapy is actually available in Europe.

Sanfilippo syndrome type A, also known as mucopolysaccharidosis type IIIA (MPS IIIA), is a rare inherited lysosomal storage disorder that primarily affects the brain. Patients lack sulfamidase, the enzyme encoded by the SGSH gene, causing heparan sulfate to accumulate within cells and progressively damage the central nervous system. The disease begins progressing in early childhood. Children may initially show developmental delays and then gradually lose previously acquired abilities.

Rebisufligene etisparvovec uses an AAV9 viral vector and is designed to deliver a functional SGSH gene into the body through a single intravenous infusion, enabling cells to produce the missing enzyme. This is the biological basis on which the therapy aims to intervene in the course of the disease. However, this announcement provided no new clinical efficacy data, adverse reaction rates, or long-term follow-up results, so the news of the application’s acceptance cannot be used to estimate how much neurological function it could preserve.

According to the company’s announcement and RTTNews’s report, the therapy was approved by the U.S. Food and Drug Administration (FDA) on September 17, 2026. The European application must still complete the review process there. The therapy previously received EMA’s PRIority MEdicines (PRIME) designation and orphan drug designation. These provisions can support the development and evaluation of medicines for serious, rare diseases, but likewise do not guarantee marketing authorization.

Even if the therapy subsequently passes regulatory review, whether patients can obtain treatment involves another level of assessment. The company said the application would be included in the European Union’s Joint Clinical Assessment (JCA) framework, which coordinates the assessment of clinical evidence among member states. This forms part of the pathway to patient access, while national pricing and reimbursement processes may still affect actual availability.

Ultragenyx has also begun engaging with regulators in the United Kingdom and Saudi Arabia as it seeks to expand into additional regions. The most concrete change for now is that European scientific review can begin. This announcement has not yet answered whether additional clinical or manufacturing information will be required, when the review will be completed, or which patients will ultimately be eligible.