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news.Regenxbio has announced the acceptance of its biologics license application (BLA) by the US Food and Drug Administration (FDA) of its gene therapy clemidsogene lanparvovec (RGX-121) for review to potentially treat Mucopolysaccharidosis II (MPS II), also referred as Hunter syndrome.
The IDS gene delivery within CNS cells offers a permanent source of secreted iduronate-2-sulfatase protein, capable of crossing the blood-brain barrier. Credit: Robina Weermeijer on Unsplash.
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The agency has granted the application priority review, setting a Prescription Drug User Fee Act (PDUFA) target action date of 9 November 2025.
The therapy has secured several designations from the US regulator, including rare paediatric disease, orphan drug product, regenerative medicine advanced therapy (RMAT), and fast track.
Additionally, it has secured the European Medicines Agency’s (EMA) advanced therapy medicinal products (ATMP) classification.
This one-time adeno-associated virus (AAV) therapeutic is intended for treating boys with MPS II, an X-linked recessive disease characterised by a deficiency in the lysosomal enzyme iduronate-2-sulfatase (I2S).
The strategic partnership with Nippon Shinyaku’s subsidiary NS Pharma, announced in January this year, will see the commercialisation of the therapy in the US following potential approval from the agency.
The approval could also lead to Regenxbio receiving a priority review voucher (PRV), with the company retaining all rights and proceeds from any potential sale of the PRV for the therapy.
Regenxbio CEO and president Curran Simpson said: “Supported by positive biomarker data and long-term outcomes, RGX-121 has the potential to be a first-in-class gene therapy that could dramatically transform the MPS II treatment landscape and reduce the significant burden patients and families currently face with weekly enzyme replacement therapy.”
RGX-121 is tailored to deliver the iduronate-2-sulfatase (IDS) gene to the central nervous system (CNS).
This delivery within CNS cells claims to offer a permanent source of secreted iduronate-2-sulfatase (I2S) protein, capable of crossing the blood-brain barrier and enabling long-term correction of cells throughout the CNS.
Hunter syndrome is said to result in the accumulation of glycosaminoglycans (GAGs), including heparan sulphate (HS). This accumulation leads to dysfunction in the cell, organ, and tissue, particularly affecting the CNS.
