Regenxbio and Nippon Shinyaku form $810m gene therapy partnership

Regenxbio has announced a strategic partnership with Nippon Shinyaku of Japan, valued at $810 million, to promote the development of gene therapies for mucopolysaccharidosis (MPS), a rare metabolic disorder. This collaboration focuses on two of Regenxbio's advanced gene therapy products, RGX-121 and RGX-111. As part of the agreement, Regenxbio will receive an initial payment of $110 million and may earn up to $700 million through various development, regulatory, and sales milestones. Nippon Shinyaku gains the rights to co-develop and commercialize these therapies in select markets.

MPS is a collection of uncommon inherited metabolic conditions caused by the lack or dysfunction of specific enzymes necessary for breaking down glycosaminoglycans (GAGs), which are complex sugar molecules. The buildup of GAGs results in progressive damage to tissues and organs, developmental delays, and in severe instances, early mortality.

The more advanced candidate in the collaboration, RGX-121 (clemidsogene lanparvovec), is designed to treat Hunter syndrome, also known as MPS II. This condition is caused by a mutation in the iduronate-2-sulfatase (IDS) gene. RGX-121 aims to deliver a functional copy of the IDS gene, addressing the root cause of the disorder. Hunter syndrome symptoms include cognitive impairment, skeletal abnormalities, and organ enlargement.

In September 2024, Regenxbio reported encouraging results from the Phase II/III CAMPSIITE trial of RGX-121. The trial showed an 85% median reduction in cerebrospinal fluid (CSF) levels of heparan sulphate (HS) D2S6, a critical biomarker linked to disease activity. In June 2024, the company announced a collaboration 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 anticipated in 2025, and Regenxbio retains rights to a priority review voucher (PRV) for RGX-121.

The second therapeutic asset, RGX-111, is being developed to combat mucopolysaccharidosis type I (MPS I), which results from mutations in the α-l-iduronidase (IDUA) gene. The therapy aims to introduce a functional copy of the IDUA gene directly to the central nervous system (CNS), potentially alleviating cognitive decline and other symptoms.

Interim data from an ongoing Phase I/II trial has reported a favorable safety profile and promising biomarker data suggesting CNS activity.

Regenxbio continues to expand its comprehensive pipeline of gene therapies targeting rare diseases. The company’s program for wet age-related macular degeneration (wAMD), ABBV-RGX-314, in collaboration with AbbVie, is undergoing evaluation in two pivotal trials, ATMOSPHERE and ASCENT. Plans are in place for a Phase III study of the therapy in diabetic retinopathy.

Moreover, the company is advancing RGX-202, a gene therapy for Duchenne muscular dystrophy. Following positive results from a Phase I/II trial, Regenxbio has aligned with the FDA on an accelerated approval pathway, with a BLA submission expected in 2026.

This strategic partnership represents a significant step forward in addressing rare genetic conditions, bringing hope to patients and families affected by these challenging disorders.