Study to Evaluate the Efficacy and Safety of BMN 333 Versus Vosoritide in Children With Achondroplasia

What Was Tested

In this phase 2, phase 3 trial, researchers set out to test Vosoritide.

This is a multicenter, multinational, randomized, active-controlled, operationally seamless Phase 2/3 study of BMN 333 in treatment-naïve pediatric participants with achondroplasia (ACH).

The study consists of a Phase 2 part and a Phase 3 part.

It had six arms (groups): one (experimental), one (experimental), one (experimental), Phase 2: Vosoritide (active comparator) and one (experimental).

The registry classes the interventions as drug.

More on the Plan

The main purpose of this study is to evaluate the effects of BMN 333 on growth compared with vosoritide in participants with achondroplasia who have not received any growth-promoting treatments.

Study details for either Phase 2 or Phase 3 include the following: * Study duration: up to 61 weeks (from screening to Safety Follow-up visit) * Treatment duration: 52 weeks.

Treatment frequency: BMN 333, once weekly; vosoritide, once daily.

Who Took Part

160 planned participants were the target.

It was open to people of any sex aged from 2 years up to 17 years.

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

Examples of who could join: Participants must be aged ≥ 2 to \< 11 years (Phase 2) or ≥ 2 to \< 18 years (Phase 3), at the time of signing the informed consent. Participants must have ACH (confirmed by documented genetic testing) and open epiphyses. Are Tanner Stage I (Phase 2) or any Tanner stage (Phase 3). Are ambulatory and able to stand without assistance.

The full record lists 4 inclusion and 6 exclusion criteria; among the exclusions: have any short stature condition other than ach (eg, hypochondroplasia, trisomy 21, pseudoachondroplasia, gh deficiency); have had bone fractures of the long bones or spine within 6 months prior to screening; have been treated with gh, insulin-like growth factor 1, or anabolic steroids in the 6 months prior to treatment start.

How the Study Was Run

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

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

Groups ran in parallel: each of the participants stayed in one arm throughout.

In this single-blind Vosoritide study one party knew the assignments and the other did not.

Those kept unaware of assignments: outcomes assessor.

It started in 2026-04-20 with completion listed for 2029-06.

It ran at 28 sites in United States (9), United Kingdom (6), Japan (3), Canada (2), Italy (2) and Romania (2).

Its stated primary purpose is treatment.

What Was Measured

The main thing measured (primary outcome): Phase 2: Predicted Annualized Growth Velocity (AGV) at Week 52 (based on AGV at Weeks 26, 39, and 52 [available cumulative data] (time frame: 52 weeks). Phase 3: Annualized Growth Velocity (AGV) at Week 52 (time frame: 52 weeks).

It also tracked 16 secondary outcomes, for example Phase 2: AGV at Weeks 26 and 52, Phase 2: Change from Baseline in standing height, Phase 2: Change from Baseline in height Z-score, Phase 2: Change from Baseline in upper to lower body segment ratio, Phase 2: Incidence of adverse events (AEs) and Phase 2: Incidence of serious adverse events (SAEs).

What This Means in Plain Language

Put simply, this is a phase 2, phase 3, randomized trial of Vosoritide in 160 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.