While Denali Therapeutics awaits a delayed FDA decision on its Hunter syndrome drug, the biotech is already banking on the therapy’s commercial success.
The agency had originally been due to make an approval call for the enzyme replacement therapy, called tividenofusp alfa, in early January 2026. But the FDA recently pushed back the decision date by three months.
While Denali waits for the regulator’s verdict in April, the biotech is busy leveraging the potential sales tividenofusp alfa could bring in. This morning’s deal with Royalty Pharma, a buyer of biopharmaceutical royalties, will give Denali access to $200 million if the drug secures FDA approval, with an additional $75 million to follow if the therapy gets the green light in Europe.
In return, Royalty will receive a 9.25% royalty on worldwide sales of tividenofusp alfa from Denali until it reaches three times the amount Royalty has handed to Denali—or, alternatively, 2.5 times the amount if the target is achieved by the first quarter of 2039.
“We are delighted to partner with Denali and acquire a royalty on tividenofusp alfa, an innovative therapy that addresses a significant unmet need in the cognitive and physical manifestations of Hunter syndrome,” Royalty’s CEO and founder Pablo Legorreta said in the release.
“Denali’s technology platform delivers therapeutics across the blood-brain barrier and is a promising new approach to brain diseases,” Legorreta added. “We are thrilled to establish a relationship with Denali and believe tividenofusp alfa is a potential practice-changing therapy that could transform the lives of patients with Hunter syndrome.”
Royalty has penned similar financing deals so far this year, helping Biogen bankroll phase 3 development of its lupus candidate litifilimab, allowing Zenas BioPharma to complete work on its autoimmune candidate obexelimab and supporting Revolution Medicines in commercializing its lung cancer drug daraxonrasib.
Denali already had almost $873 million in the bank at the end of September. CEO Ryan Watts, Ph.D., said the additional funds from Royalty would ensure the biotech was “well positioned to advance our development programs as we prepare for the launch of tividenofusp alfa, unlocking broad opportunities across serious diseases.”
Tividenofusp alfa is a version of the iduronate 2-sulfatase enzyme that is engineered to penetrate the blood-brain barrier by binding to transferrin receptor 1, which normally shuttles iron into the brain.
When Denali revealed the three-month delay to the FDA’s decision date back in October, the company put the move in the context of the updated clinical pharmacology information it had supplied to the FDA as part of the application review process. While Denali said this information was not related to the drug’s efficacy, safety or biomarkers, and did not involve supplying any additional clinical data, the FDA classified the submission as a major amendment to the application, which requires a three-month extension to the deadline.
Hunter syndrome, also called mucopolysaccharidosis type II (MPS II), is characterized by patients' inability to break down certain sugars, which leads to tissue and organ damage that ultimately causes stiff joints, delayed growth and enlarged spleens and livers, among other symptoms. The disease can also lead to cognitive and behavioral problems, and, in severe cases, patients may not survive beyond their teenage years.
There is one approved enzyme replacement therapy for Hunter syndrome in Takeda’s Elaprase, which the Japanese drugmaker secured as part of its acquisition of Shire Pharmaceuticals in 2019.
In August, the FDA pushed back the approval decision deadline for another Hunter syndrome treatment in the form of Regenxbio’s gene therapy clemidsogene lanparvovec after requesting additional data.