CNP analog · achondroplasia growth
A lab-made version of C-type natriuretic peptide (CNP), a natural regulator of bone growth. It is injected under the skin in children with achondroplasia, a genetic form of short stature caused by a gain-of-function change in the FGFR3 gene, to increase how fast they grow while their growth plates are still open.
In achondroplasia, a gain-of-function change in the FGFR3 receptor keeps a growth-braking signal switched on in the cartilage cells of the growth plates1. Vosoritide binds natriuretic peptide receptor B (NPR-B), and the resulting signal blocks the FGFR3 pathway downstream, at the RAF-1 step of the MAPK (ERK1/2) cascade1. That lets growth-plate cartilage cells multiply and mature, the process that lengthens bones.
In animals with open growth plates it widened the growth plate and increased skeletal growth, and in mouse models of FGFR3-related dwarfism it partly or fully normalized the dwarfism phenotype1; these are animal findings. The molecule is 39 amino acids long: the last 37 amino acids of human CNP-53 plus two added at the front, which make it resistant to breakdown by the enzyme neutral endopeptidase1.
The evidence is from children with achondroplasia. In a 52-week phase 3 trial in 121 children aged 5 to under 18, vosoritide raised annualized growth velocity by 1.57 cm per year more than placebo; the authors noted that effects on final adult height and long-term harms were unknown2.
In the open-label extension, treated children were 5.75 cm taller after three years than untreated children from an external comparison group, with treatment lasting up to six years3. In a phase 2 trial in infants and children under 5 (75 enrolled, 64 randomized), height Z score rose 0.25 more than with placebo, with a confidence interval that included zero4.
In hypochondroplasia, a related FGFR3 condition, a 2026 phase 3 trial in 81 children reported growth velocity 2.33 cm per year higher than placebo5; that use is not on the current US label1.
The FDA granted accelerated approval in November 2021 to Voxzogo (BioMarin) to increase linear growth in children with achondroplasia whose growth plates are open; continued approval may depend on confirmatory trials. The current US label does not include hypochondroplasia.
Per the FDA label, the most common effects (over 10%) are injection-site redness, swelling and hives, rash, vomiting, joint pain, decreased blood pressure and gastroenteritis. Brief drops in blood pressure, sometimes with dizziness, fatigue or nausea, were seen in trials, so patients are advised to be well hydrated and to have eaten beforehand. Children with significant heart or blood-vessel disease, or on blood-pressure medicines, were excluded from the trials.
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