Does Vosoritide work?
Yes, in controlled trials: 121 children with achondroplasia and 81 with hypochondroplasia.
A 121-child randomized placebo-controlled phase 3 trial showed a 1.57 centimeter per year increase in growth velocity over 52 weeks, the basis for approval. A second randomized trial in 81 children with hypochondroplasia, published in 2026, found 2.33 centimeters per year more growth than placebo. The endpoint in both is a surrogate (growth rate, not final height or function), which the FDA addressed by granting accelerated approval. Grade A for the approved use given the randomized design and matching indication. 123
The phase 3 trial was published in The Lancet in 2020. It randomized 121 children aged 5 to under 18 with achondroplasia. They got vosoritide or placebo for 52 weeks. Annualized growth velocity rose by 1.57 centimeters per year in the vosoritide group compared with placebo (adjusted mean difference). Height z-score also improved. This measures height relative to peers. Body proportions did not change measurably within a year. 1
Approval for younger children came from a randomized trial in infants and children under 5. Open-label extension data followed the phase 3 participants for several years. They show continued growth above the untreated achondroplasia norm. The confirmatory follow-up is meant to answer two questions. Do treated children reach a taller final height? Do they have fewer spinal and airway problems? 2
Evidence checklist
- Randomised controlled trial Placebo-controlled phase 3 trials in achondroplasia and hypochondroplasia, 52 weeks
- Human study over 100 people Phase 3 had 121 children; hypochondroplasia trial 81
- More than one research group Sponsor-run trials; extensions follow-up
- Clinical outcomes, not surrogate markers Growth rate, not final height or function
- Human safety data beyond case reports Trial and label data in children
More on Vosoritide
Citations
- Savarirayan 2020, Lancet: Once-daily subcutaneous vosoritide in children with achondroplasia, randomized phase 3 trial doi.org
- FDA 2024: Voxzogo (vosoritide) prescribing information accessdata.fda.gov
- Dauber 2026, NEJM Evidence: a phase 3 trial of vosoritide in children with hypochondroplasia pubmed.ncbi.nlm.nih.gov
- BioMarin 2026: phase 3 hypochondroplasia results published in NEJM Evidence, supplemental application submitted to the FDA biomarin.com
Reference information only, not medical advice. Drawn from the Vosoritide article, fact-checked against the cited sources. No dosing anywhere on this site.