REGENXBIO Inc. and Nippon Shinyaku Co., Ltd. have announced an exclusive partnership focused on the development and commercialization of two gene therapies, RGX-121 for Mucopolysaccharidosis type II (MPS II, or Hunter syndrome) and RGX-111 for Mucopolysaccharidosis type I (MPS I, or Hurler syndrome). This collaboration aims to address the unmet needs of patients with these rare, life-threatening genetic disorders.
Strategic Collaboration Details
Under the agreement, REGENXBIO will receive an initial payment of $110 million and is eligible for up to $700 million in additional milestone payments based on development, regulatory, and sales achievements. Nippon Shinyaku will lead the commercialization efforts in the United States and Asia, while REGENXBIO will continue to spearhead the clinical development and manufacturing of both therapies. REGENXBIO retains full rights to the Priority Review Voucher (PRV) for RGX-121.
Curran M. Simpson, President and Chief Executive Officer of REGENXBIO, stated, "The structure of the agreement allows us to leverage our expertise in gene therapy manufacturing while also capturing milestones and a meaningful share of future product revenues... With Nippon Shinyaku’s expertise in rare disease and strong commercial capabilities, we look forward to working together to get both of these promising candidates across the finish line for patients."
RGX-121 for MPS II
RGX-121 is designed as a potential one-time adeno-associated virus (AAV) therapeutic for treating boys with MPS II. MPS II is caused by a deficiency in the iduronate-2-sulfatase (I2S) enzyme, leading to the accumulation of glycosaminoglycans (GAGs) and resulting in developmental delays, organ damage, and neurological complications. RGX-121 delivers the IDS gene to cells within the central nervous system (CNS), aiming to provide a continuous source of secreted I2S beyond the blood-brain barrier for long-term correction.
RGX-121 has been granted Orphan Drug Product, Rare Pediatric Disease, Fast Track, and Regenerative Medicine Advanced Therapy designations by the U.S. Food and Drug Administration (FDA), as well as advanced therapy medicinal product (ATMP) classification from the European Medicines Agency.
RGX-111 for MPS I
RGX-111 utilizes the AAV9 vector to deliver the α-l-iduronidase (IDUA) gene to the CNS. MPS I results from a deficiency in the IDUA enzyme, causing GAG accumulation and leading to cognitive deficits and skeletal abnormalities. By providing rapid IDUA delivery to the brain, RGX-111 aims to prevent the progression of cognitive decline in MPS I patients. Positive interim data from a Phase I/II trial of RGX-111 were reported in February 2023. RGX-111 has also received Orphan Drug Product, Rare Pediatric Disease, and Fast Track designations from the FDA.
Toru Nakai, President and Representative Director of Nippon Shinyaku, commented, "RGX-121 and RGX-111 represent one-time gene therapies that can potentially change the course of MPS disease, and we are very pleased to be partnering with REGENXBIO, experts in gene therapy development and manufacturing. We are confident these therapies can bring tremendous value to those living with MPS II and I."
Addressing Unmet Needs in MPS I and MPS II
Currently, enzyme replacement therapies (ERT) such as idursulfase (Elaprase) for MPS II and laronidase (Aldurazyme) for MPS I are available, but they do not fully address the neurological damage associated with these conditions. Hematopoietic stem cell transplantation (HSCT) is another option, but its benefits are limited to early-stage disease. Gene therapy offers a potential long-term solution by directly addressing the underlying genetic defect.
The transaction is expected to close by the end of the first quarter of 2025, subject to customary conditions and regulatory approvals.
