Regenxbio MPS II gene therapy gets priority review, November PDUFA date

The U.S. FDA has accepted Regenxbio’s BLA for clemidsogene lanparvovec (RGX-121) for the treatment of mucopolysaccharidosis II, granting it priority review with a PDUFA target action date of November 9, 2025.

MPS II, also known as Hunter syndrome, is a rare disease where the body can't break down sugar molecules. It is caused by a variation in the IDS gene, which contains the instructions for the production of a specific enzyme, I2S. RGX-121, an AAV therapeutic designed to deliver a functional copy of the I2S gene directly to the central nervous system, is on track to be the first gene therapy and one-time treatment for the disease.

The treatment is being developed and potentially commercialized in partnership with Nippon Shinyaku, per a deal signed back in January. The deal gives the Japan-based drugmaker the rights to commercialize two Regenxbio products in the U.S. and Asia — RGX-121 and RGX-111 for mucopolysaccharidosis I (MPS I), also known as Hurler syndrome. Per the deal, Nippon Shinyaku paid Regenxbio $110 million upfront and will pay up to an additional $700 million if certain milestones are achieved.

RGX-121 has received orphan drug product, rare pediatric disease, fast track and regenerative medicine advanced yherapy (RMAT) designations from the FDA and advanced therapy medicinal products (ATMP) classification from the EMA.