NEW YORK – Regenxbio and Nippon Shinyaku on Tuesday said they are partnering to develop and commercialize gene therapies for Hunter and Hurler syndromes in a deal valued at $810 million.
Under the terms of the agreement, Nippon Shinyaku will pay Regenxbio $110 million upfront and up to $700 million if Regenxbio meets certain milestones, including $40 million in development and regulatory milestones and $660 million in sales milestones. Regenxbio is also eligible to receive double-digit royalties on net sales on products commercialized in the US and Asia.
The partnership will focus on advancing RGX-121 as a treatment for mucopolysaccharidosis II (MPS II), also known as Hunter syndrome, and RGX-111 for treating mucopolysaccharidosis I (MPS I), also called Hurler syndrome. RGX-111 has demonstrated promising results in a Phase I/II trial, and Regenxbio is hoping RGX-121 will net regulatory approval in the US later this year.
Last year, Regenxbio said it would file a biologics license application with the US Food and Drug Administration after RGX-121 demonstrated favorable efficacy in the pivotal CAMPSIITE trial. Levels of D2S6, a biomarker of I2S activity, a key enzyme deficient in Hunter syndrome, fell by a median 86 percent among patients treated with RGX-121 at 16 weeks and approached normal levels.
Hunter syndrome is caused by mutations in the IDS gene, which itself causes deficiencies in the I2S protein, keeping it from breaking down complex sugars in the body and leading to a host of problems, including macrocephaly and heart problems. RGX-121 is designed to deliver a normal IDS gene to the central nervous system and produce a protein that is structurally the same as normal I2S. RGX-111, meanwhile, is designed to deliver a non-mutated form of the IDUA gene that is mutated in Hurler syndrome patients to the central nervous system and aims to prevent the cognitive deficits that affect patients.
In the latest deal, slated to close in the first quarter of 2025, Nippon Shinyaku will be responsible for commercializing both RGX-121 and RGX-111 in the licensed territories of the US and Asia, while Regenxbio will manufacture them and lead future clinical development efforts. Regenxbio will retain the right to develop and commercialize the gene therapies outside the licensed territory. It will also keep the priority review voucher that it will receive should RGX-121 garner approval in the US as a rare pediatric disease-designated product and retain all the proceeds should it sell the voucher.
"RGX-121 and RGX-111 represent one-time gene therapies that can potentially change the course of MPS disease," Toru Nakai, president and representative director of Nippon Shinyaku, said in a statement. "We are confident these therapies can bring tremendous value to those living with MPS II and I."