With a phase 3 win now fleshed out and an FDA filing recently submitted, BioMarin is advancing expansion plans for Voxzogo, looking to extend the dwarfism drug’s reach as it faces new pressure in its inaugural achondroplasia indication.
On Wednesday, BioMarin unveiled detailed results from the phase 3 CANOPY-HCH-3 trial assessing Voxzogo in children with hypochondroplasia (HCH), a milder form of achondroplasia, where the company announced a topline win back in May.
Aside from the average 2.33 cm/year improvement in annualized growth velocity (AGV) on Voxzogo that BioMarin reported out earlier this year, the company dug deeper into the magnitude of benefit its medicine could offer to children with HCH across measures like standing height and arm span after a year of treatment.
BioMarin shared the data Wednesday at the European Society for Paediatric Endocrinology annual meeting and simultaneously published the results in the New England Journal of Medicine.
Additionally, BioMarin confirmed that it “recently submitted” its expansion filing to the FDA and remains “on track” to submit applications with the European Medicines Agency and other global regulators. Should the drug win approval in the new HCH niche, BioMarin is targeting a 2027 launch.
HCH is a rare, genetic condition that impedes bone growth, leading to disproportionate short stature and skeletal differences that can affect the long bones, spine and other parts of the body. The condition has the potential to hamper physical function and overall quality of life, BioMarin said in in a Sept. 9 release.
Caused by a mutation in the FGFR3 gene, HCH slows the conversion of cartilage into bone and patients with the condition typically exhibit an average-sized torso but disproportionately short arms, legs, hands and feet.
The condition is often diagnosed in toddlerhood or when children or early school age, with BioMarin estimating there are some 14,000 kids living with the HCH who are also “within the company’s global footprint” and who may ultimately be eligible to receive Voxzogo.
Moving beyond the AGV metric that helped the trial meet its primary endpoint, BioMarin noted that children who received Voxzogo also charted a significant 2.35 cm standing height improvement and a 1.03 cm arm span improvement over placebo. Moreover, kids on the study drug showed “numerical improvements in quality of life,” BioMarin said, adding that it will continue to assess its treatment’s impact over the long term.
The company noted that Voxzogo’s safety score card came out consistent with its profile in previous studies, with most adverse events logged being classified as mild. The phase 3 trial reported no treatment-related serious adverse events.
Speaking to the results, Andrew Dauber, M.D., the CANOPY-HCH-3 studies lead investigator, noted that the “changes we observed in annualized growth velocity and arm span provide encouraging evidence of how children with hypochondroplasia responded to treatment throughout the study.”
He continued, “These findings deepen our understanding of the condition while reinforcing Voxzogo’s potential as the first targeted medicine developed specifically for children with hypochondroplasia."
Voxzogo scored its initial FDA nod to treat achondroplasia in children ages 5 years and older in late 2021 before subsequently expanding its label to include kids younger than 5 in 2023.
Still, analysts at Leerink Partners cautioned earlier this year after BioMarin reported its topline success that while an “important win for the Voxzogo franchise,” they remained cautious about the drug’s prospects in HCH, which they said alone was “unlikely to offset growing competitive pressures emerging in [achondroplasia].”
That newfound competition comes in the form of Ascendis’ Yuviwel, a once weekly injection approved in March to treat kids ages 2 and older with achondroplasia and who have open growth plates.
That said, BioMarin clinched a victory on that front late last month, winning an agreement from Ascendis to pay 20% of Yuviwel net sales in the U.S. from its initial launch out to May 2030. BioMarin had claimed that Ascendis' drug treads on its own patents and has also lined up royalty agreements with its rival in the European Union, Brazil and South Korea.
For its part, Voxzogo ginned up $927 million in full-year 2025 sales, representing a 26% increase over 2024 and accounting for some 29% of BioMarin’s revenue last year.