RecruitingPHASE2, PHASE3INTERVENTIONAL

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

This study is for children with achondroplasia, a condition that affects how bones grow, leading to shorter stature. We are testing a new medicine called BMN 333 against an existing treatment, Vosoritide (also known as Voxzogo). The main goal is to see how effectively BMN 333 helps children grow and if it is safe to use. This research is divided into two main parts. The first part helps decide the best dose of BMN 333, and the second part will compare this chosen dose directly with Vosoritide. Children taking part must not have received other growth-promoting treatments for their achondroplasia before joining the study.

At a glance

Status

Recruiting

Phase

PHASE2, PHASE3

Sponsor

BioMarin Pharmaceutical

Enrolment target

160

Start

01 Apr 2026

Estimated completion

01 Sep 2029

Achondroplasia

What is this study about?

This study is for children who have achondroplasia, a condition often called dwarfism, which affects bone growth and leads to shorter arms and legs. While there are some treatments available, scientists are always looking for new and better ways to help children with this condition.

This research is testing a new medicine, called BMN 333, against an existing treatment, Vosoritide (you might know it as Voxzogo). The main purpose is to see if BMN 333 can help children grow more effectively than Vosoritide and to make sure it's safe to use. The study is split into two main sections: first, researchers will find the best dose of BMN 333 to use, and then they will compare that dose directly with Vosoritide.

Taking part in this study could help doctors understand more about treating achondroplasia. Your child would be carefully monitored throughout the study by a team of medical professionals. The information learned from participants could help future generations of children with achondroplasia.

Key takeaways

Aims to compare a new medicine (BMN 333) with an existing one (Vosoritide) for achondroplasia.
For children aged 2-17 years with achondroplasia who haven't had prior growth treatments.
Treatment involves weekly (for BMN 333) or daily (for Vosoritide) injections for 52 weeks.
Study duration is up to 14 months, including regular clinic visits and follow-up.
The study seeks to understand effects on growth and safety.

Who may be eligible?

This study is open to boys and girls who have achondroplasia. They need to be between 2 and 17 years old. It's really important that their achondroplasia has been confirmed by a genetic test, and that their growth plates (the areas where bones grow) are still open.

Children generally need to be able to walk and stand on their own without help. They also shouldn't have any other conditions that cause short stature. If they have certain medical conditions like untreated thyroid problems, poorly controlled diabetes, or serious heart or kidney issues, they might not be able to join.

Crucially, children cannot have received Vosoritide or any other medicine, treatment, or medical device specifically for achondroplasia or short stature before. They also shouldn't have had certain other growth-related treatments in the 6 months leading up to the study, like growth hormone or certain steroids.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Is your child aged between 2 and 17 years old?
Does your child have achondroplasia confirmed by a genetic test?
Can your child walk and stand on their own?
Has your child *never* received any other drugs specifically for achondroplasia before (like Vosoritide or growth hormone in the last 6 months)?
Does your child *not* have other serious medical conditions like untreated thyroid issues or significant heart problems?

Answer every question to see your result.

What does participation involve?

If your child joins this study, they will receive either BMN 333 or Vosoritide. BMN 333 is given once a week, and Vosoritide is given once a day, both as an injection. The treatment part of the study will last for 52 weeks (about one year).

Throughout the study, your child will have regular visits to the clinic for check-ups, assessments, and to check how they are growing. The medical team will also look for any side effects. The total time active in the study, from your first visit to the final check-up after treatment, will be up to 61 weeks (around 14 months).

There will be follow-up visits after the treatment finishes to monitor your child's health and safety.

Potential risks and benefits

Participating in this study might offer your child a chance to receive a new investigational treatment or an existing approved treatment for achondroplasia, potentially helping with their growth. However, like all medicines, BMN 333 and Vosoritide can have side effects, which the study team will discuss with you. There's also no guarantee that the treatment will be effective for your child. The study will involve regular clinic visits, blood tests, and receiving injections, which can be time-consuming and sometimes uncomfortable. You are free to withdraw your child from the study at any time, for any reason, without it affecting their usual medical care.

Locations (10)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

UCSF Benioff Children's Hospital Oakland
Verified postcode
Oakland, United States· Recruiting
Ann & Robert H. Lurie Children's Hospital of Chicago
Verified postcode
Chicago, United States· Not yet recruiting
Johns Hopkins Medicine Julie
Verified postcode
Baltimore, United States· Not yet recruiting
Texas Children Hospital, Baylor College of Medicine, Houston TX
Verified postcode
Houston, United States· Recruiting
Consano Clinical Research, LLC
Verified postcode
San Antonio, United States· Recruiting
Murdoch Children's Research Institute
Verified postcode
Parkville, Australia· Recruiting
Irccs Ospedale Gaslini Di Genova
Verified postcode
Genova, Italy· Not yet recruiting
Craiova Emergency Clinical County
Verified postcode
Craiova, Romania· Not yet recruiting
Seoul National University Hospital
Verified postcode
Seoul, South Korea· Not yet recruiting
University Hospitals Bristol NHS Foundation Trust - Bristol Royal Hospital for Children
Verified postcode
Bristol, United Kingdom· Not yet recruiting

Common questions

What is achondroplasia?

Achondroplasia is a genetic condition that affects how bones grow, leading to shorter arms, legs, and a normal-sized torso. It's the most common type of dwarfism.

What is the difference between BMN 333 and Vosoritide?

BMN 333 is a new medicine being tested in this study. Vosoritide (Voxzogo) is an existing medicine approved for treating achondroplasia. This study compares them.

Will my child definitely get the new medicine?

Participants will be randomly chosen to receive either BMN 333 or Vosoritide. Neither you nor the study doctor will choose which treatment your child receives.

How long will the treatment last?

The treatment period for this study is 52 weeks, which is about one year, with follow-up visits afterwards.

What do the 'Phase 2' and 'Phase 3' parts mean?

Clinical trials are done in phases. Phase 2 checks for the right dose and initial safety, and Phase 3 compares the new treatment against an existing one in a larger group of people to confirm its effectiveness and safety.

How to find out more

Trial Specialist

medinfo@bmrn.com 1-800-983-4587 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.