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

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.

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.