(P1) BioMarin’s top-selling drug Voxzogo significantly improved growth in children with a second form of dwarfism, setting up a potential label expansion that could add hundreds of millions in sales but faces questions over market size and new competition. The drug showed a 2.33 centimeter per year increase in growth velocity for children with hypochondroplasia (HCH).
(P2) "Seeing these improvements in growth is a milestone we have hoped for after so many years without treatment options,” Andrew Dauber, the lead study investigator and chief of endocrinology at Children's National Hospital, said in a release. “These data suggest we may be approaching a new era in how we care for children with hypochondroplasia.”
(P3) The Phase 3 study enrolled 80 children aged 3 to 17. At 52 weeks, patients treated with Voxzogo showed a highly statistically significant improvement in annualized growth velocity compared to placebo. The trial also met key secondary goals, showing significant increases in standing height and arm span, which the company noted is crucial for patient independence.
(P4) With the successful data, BioMarin plans to submit for regulatory approval in the U.S. in the third quarter of this year, followed by submissions in Europe. While analysts see the results as a win, they highlight the challenge of developing a market for the milder HCH and fending off new rivals in the larger achondroplasia market, where Voxzogo’s dominance is ending.
Hypochondroplasia (HCH) is a rare genetic condition caused by a mutation in the FGFR3 gene, which slows the conversion of cartilage into bone, resulting in short-limbed dwarfism. It is a milder form of achondroplasia (ACH), the most common type of dwarfism, for which Voxzogo first gained FDA approval in 2021. Because its effects can be less severe, HCH may not be diagnosed until later in childhood, and as Raymond James analyst Christopher Raymond noted, there may be less "urgency to treat."
The results position BioMarin ahead of competitors in the HCH space. However, the landscape for its core ACH indication is heating up. Two months ago, Ascendis Pharma won FDA approval for its once-weekly injection, Yuviwel, a direct challenge to Voxzogo's daily dosing schedule. Meanwhile, BridgeBio plans to file for approval of its oral drug, infigratinib, in the second half of the year after a successful Phase 3 trial.
The success in HCH provides an incremental expansion for the Voxzogo franchise, which accounted for $927 million in sales in 2025. Evercore ISI analyst Cory Kasimov projects the new indication could generate $600 million in peak sales, noting BioMarin has set a "relatively high efficacy bar" for rivals. Raymond James estimates a more conservative $178 million in U.S. revenue within five years, with additional international sales.
Still, Leerink Partners analysts remain cautious, writing that "success in HCH alone is unlikely to fully offset growing competitive pressures emerging in ACH.” They also pointed to the need for BioMarin to "drive disease awareness and enhance the diagnosis journey" for the less-diagnosed HCH population. BioMarin's stock (BMRN) rose on the news, as the positive data de-risks the program's expansion. The company's ability to build the HCH market will be critical to realizing the drug's full potential amid a changing competitive environment.
This article is for informational purposes only and does not constitute investment advice.
