A Study of Vosoritide Versus Placebo in Children With Hypochondroplasia Aged 0 to < 36 Months

What Was Tested

In this phase 2 trial, researchers set out to test Vosoritide.

It had two arms (groups): Vosoritide injection with vial and syringe (experimental) and Placebo injection with vial and syringe (placebo comparator).

The registry classes the interventions as drug.

More on the Plan

Eligible participants with documented HCH confirmed by genetic testing will be randomized in a 1:1 ratio to receive vosoritide or placebo.

Participants will receive study treatment daily for 52 weeks by subcutaneous (SC) injection, followed by a 2-week safety follow-up visit.

Who Took Part

60 planned participants were the target.

It was open to people of any sex aged from 0 months up to 36 months.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: Participants must be 0 to \< 36 months of age at randomization. Participant's weight at the Day 1 visit (pre-treatment) must be ≥ 3 kg.

The full record lists 4 inclusion and 11 exclusion criteria; among the exclusions: short stature condition other than hch (eg, ach, trisomy 21, pseudoachondroplasia); have an unstable medical condition likely to require surgical intervention during the study period; taking any of the prohibited medications.

How the Study Was Run

The set-up was randomized, parallel-group and quadruple-blind.

The participants were allocated by chance, so the Vosoritide group and the comparison group should start out alike.

The Vosoritide group and the comparison group ran side by side rather than switching.

As a double-blind Vosoritide study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant, care provider, investigator and outcomes assessor.

It started in 2025-07-30 with completion listed for 2028-06-30.

It ran at 26 sites in United States (10), Japan (5), Germany (3), Australia (2), France (2) and Italy (2).

Its stated primary purpose is treatment.

What Was Measured

Primary outcome: Incidence of treatment-emergent adverse events (time frame: From baseline to end of treatment at 52 weeks). Incidence of serious adverse events versus placebo over the course of the study (time frame: From baseline to end of treatment at 52 weeks). Changes from baseline in heart rate (time frame: At week 13, at week 26, at week 39, at week 52).

It also tracked 19 secondary outcomes, for example Change in height, Cumulative annualized growth velocity (AGV), 6-month interval AGV, Change from baseline in upper to lower body segment ratio, Change from baseline in arm span and Change from baseline in total body (less head) bone mineral density (BMD) Z-score.

What This Means in Plain Language

Put simply, this is a phase 2, randomized trial of Vosoritide in 60 people.

It is still recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Vosoritide compound page, all human trials.