Phase 3 results “exceeded” BioMarin’s expectations, according to head of research and development Greg Freeberg, MD, and the California biotech appears poised to win label expansion for its best-selling product, dwarfism treatment Voxzogo.
The Canopy-HCH-3 study in children with achondroplasia (HCH) met its primary endpoint, with Voxzogo producing “highly statistically significant” improvements in annual growth velocity (AGV), the company said. In a study of 80 patients between the ages of 3 and 17, the AGV of patients who took Voxzogo was 2.33 centimeters higher than those who took a placebo at week 52.
In addition, Voxzogo produced statistically significant increases in two other height measurements (standing height and height Z-score) and arm width measurements. The company says this is important in providing long reach to patients and enabling independence.
Andrew Dover, the study’s principal investigator and chief of endocrinology at Children’s National Hospital in Washington, D.C., said the results were “very encouraging.”
“After many years without treatment options, seeing this improvement in growth is a milestone we had hoped for,” Dauber added in the release. “These data suggest that we may be approaching a new era in how children with achondroplasia are cared for.”
HCH is a rare genetic disease that restricts bone growth and causes short-limbed dwarfism. It is caused by a mutation in the FGFR3 gene that slows down the conversion of cartilage to bone. Patients with HCH typically have an average-sized torso but disproportionately short arms, legs, hands, and feet. This condition can cause otorhinolaryngological (ear, nose, and throat) problems and neurological complications.
HCH is a milder form of achondroplasia (ACH). In 2021, the FDA approved the CNP analog Voxzogo for the treatment of ACH, and two years later expanded its eligibility to children under 5 years of age.
Following these results, which the company plans to present in full at a medical congress later this year, BioMarin said it plans to apply for approval of Voxzogo in HCH in the third quarter of this year, and then to the European Medicines Agency and other regulatory authorities.
“While this is an important win for the Voxzogo franchise and provides a step-change expansion beyond achondroplasia (ACH), we remain cautious that success in HCH alone is unlikely to fully offset the increasing competitive pressures occurring in ACH,” Leerink Partners analysts wrote in a note to clients.
Two months ago, Ascendis received FDA approval for its ACH treatment Ubiwell. The approval is for children ages 2 and older who have open growth plates (areas where cartilage develops and stretches at the ends of bones). The advantage that Yuviwel offers is that it is administered weekly as opposed to daily for Voxzogo.
In February, BridgeBio announced the success of a Phase 3 trial of its FGFR1-3 selective tyrosine kinase inhibitor infigratinib in children with ACH. BridgeBio and its partner Kyowa Kirin plan to apply for approval of infigratinib in the second half of this year.
“HCH is not diagnosed at the same rate as ACH, so we believe it will be important to understand how BioMarin plans to increase awareness of the disease and help strengthen the process of diagnosis,” Leerink added. “Based on (KOL’s) discussions, we believe that there is a fairly wide range of severity for HCH, and that some patients may already be taking Voxzogo while others may have mild symptoms.”
Voxzogo’s sales increased 26% to $927 million, accounting for 29% of the company’s 2025 revenue. The Leerink team said it expects “peak sales to be significantly lower for HCH compared to ACH.”
In March, BioMarin announced that it had discontinued a Phase 2 trial of Voxzogo in three potential indications: Turner syndrome, SHOX deficiency, and aggrecan (ACAN) deficiency. A Phase 2 trial of Voxzogo in children with Noonan syndrome and idiopathic short stature (ISS) without ACAN deficiency is ongoing.
