Regenxbio files BLA for Nippon Shinyaku-partnered gene therapy for MPS II

Regenxbio has completed its BLA submission to the U.S. FDA, seeking accelerated approval of clemidsogene lanparvovec (RGX-121), a potential one-time AAV therapeutic for the treatment of boys with mucopolysaccharidosis II (MPS II).

MPS II, also known as Hunter syndrome, is a rare disease when the body can't break down sugar molecules caused by a variation in the IDS gene, which contains the instructions for the production of a specific enzyme, I2S. RGX-121, 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.

According to Regenxbio, who reported the update along with its financial results, the company anticipates the potential approval of RGX-121 in the second half of 2025. The approval could result in the receipt of a priority review voucher.