If approved, Ascendis’ TransCon CNP would become the second therapy for achondroplasia, challenging BioMarin’s Voxzogo.
The FDA has pushed the deadline out three months for its final decision on Ascendis Pharma’s achondroplasia treatment TransCon CNP.
The delay comes after Ascendis in early November filed additional information regarding a post-marketing requirement for TransCon CNP. The FDA considered this a “major amendment,” according to a news release last Wednesday, necessitating the review extension. The agency’s original target action date was Nov. 30, but Ascendis now expects the verdict to come on or before Feb. 28, 2026.
In a statement, Ascendis CEO Jan Mikkelsen said that the company has addressed “all outstanding requests from the FDA.” Ascendis will continue to work with the regulator to bring TransCon CNP to patients who need it “as soon as possible,” Mikkelsen added
Achondroplasia is a genetic disease characterized by impaired bone development. The condition affects 15,000 to 40,000 newborns and qualifies as a rare disease, though it is known as the most common cause of dwarfism. TransCon CNP, also called navepegritide, specifically addresses the achondroplasia subtype caused by overactivity of the FGFR3 gene which, aside from compromising bone growth, also manifests with neurological, muscular and cardiorespiratory issues.
Ascendis’ treatment gives patients the C-type natriuretic peptide (CNP), in turn counteracting the effects of mutated FGFR3 and helping to stimulate bone growth. Data from the Phase II ACcomplisH study published in The Lancet in November 2023, showed that TransCon CNP improved growth rates in patients with achondroplasia.
The regulatory delay for TransCon CNP should give some breathing room to BioMarin, which owns Voxzogo, the only FDA-approved treatment for achondroplasia. That drug, approved in November 2021, addresses the same disease pathway as TransCon CNP: it mimics the action of CNP and targets FGFR3 signaling, facilitating bone growth.
BioMarin is increasingly wary of the incoming competition from TransCon CNP, alongside other investigational achondroplasia therapies on the horizon, including BridgeBio’s infigratinib. During its third-quarter earnings call in October, the company revealed that it will abandon its previously announced goal of hitting $4 billion in revenue in 2027, with CFO Brian Mueller specifically citing the “impact of potential Voxzogo” competition.
