Regenxbio has entered into a strategic collaboration worth $810m with Japan-based Nippon Shinyaku to advance gene therapies targeting the rare metabolic disorder mucopolysaccharidosis (MPS).
Under the terms of the deal, which centres on two of Regenxbio’s assets – RGX-121 and RGX-111 – Regenxbio will receive $110m upfront and is eligible for up to $700m in development, regulatory, and sales milestones. Nippon Shinyaku gains rights to co-develop and commercialise the therapies in specified markets.
MPS includes a group of rare, inherited metabolic disorders caused by the absence or malfunctioning of specific enzymes required to break down glycosaminoglycans (GAGs), complex sugar molecules. The accumulation of GAGs leads to progressive tissue and organ damage, developmental delays, and in severe cases, early mortality.
The most advanced candidate in the partnership, RGX-121 (clemidsogene lanparvovec), targets Hunter syndrome, also known as MPS II, a condition caused by a mutation in the iduronate-2-sulfatase (IDS) gene. RGX-121 is designed to deliver a functional copy of the IDS gene, addressing the underlying cause of the disease. Symptoms of Hunter syndrome include cognitive impairment, skeletal abnormalities, and organ enlargement.
In September 2024, Regenxbio reported positive results from the Phase II/III CAMPSIITE trial (NCT03566043) of RGX-121, showing an 85% median reduction of cerebrospinal fluid (CSF) levels of heparan sulphate (HS) D2S6, a key biomarker linked to disease activity. In June 2024, the company announced progress with the US Food and Drug Administration (FDA) to pursue an accelerated approval pathway, with a rolling biologics license application (BLA) submission underway. An accelerated approval decision is expected in 2025, and Regenxbio retains rights to a priority review voucher (PRV) for RGX-121.
The second asset, RGX-111, is being developed for mucopolysaccharidosis type I (MPS I), caused by mutations in the α-l-iduronidase (IDUA) gene. The gene therapy aims to deliver a functional copy of the IDUA gene directly to the central nervous system (CNS), potentially slowing cognitive decline and other symptoms. Interim data from an ongoing Phase I/II trial (NCT03580083) has shown a favourable safety profile and promising biomarker data indicative of CNS activity.
Regenxbio continues to advance its broader pipeline of gene therapies for rare diseases. The company’s wet age-related macular degeneration (wAMD) programme, ABBV-RGX-314, partnered with AbbVie, is being evaluated in two pivotal trials, ATMOSPHERE (NCT04704921) and ASCENT (NCT05407636). Plans are also underway for a Phase III study of the therapy in diabetic retinopathy.
Additionally, the company is progressing RGX-202, a gene therapy for Duchenne muscular dystrophy. Following positive data from a Phase I/II trial, Regenxbio has aligned with the FDA on an accelerated approval pathway, with a BLA submission anticipated in 2026.
