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Long-Term Study of Vosoritide Safety and Effectiveness in Children with Hypochondroplasia Until Adult Height is Reached

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study is looking at a condition called hypochondroplasia, which is a genetic disorder that affects bone growth and results in shorter than average height. The treatment being tested is vosoritide, which is also known by the brand name Voxzogo. This medication is given as an injection under the skin once daily. The study will use different strengths of the medication depending on what is appropriate for each person taking part.

The purpose of this study is to look at the long-term safety and effectiveness of vosoritide treatment in children with hypochondroplasia until they reach their final adult height. This study is designed for children who have already been taking part in previous studies of this medication and still have open growth plates in their bones, which means they are still growing. The study will continue for many years, following participants as they grow, to see how the treatment affects their height over time and to watch for any side effects that may occur.

During the study, participants will receive daily injections of vosoritide, which will be given by their parent or caregiver after proper training. The study will measure changes in height and compare these measurements to standard growth charts to see if the treatment is helping children grow taller. Regular visits will be scheduled to check on the participants' growth, overall health, and any side effects from the medication. The treatment will continue until participants reach their final adult height, which is when their bones stop growing.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Entry into the extension study

    This study is a continuation for patients who have already completed 52 weeks in a previous study (either study 111-303 or study 111-212).

    Before entering this extension study, X-rays of the left hand will be taken to confirm that the growth plates (areas of growing tissue near the ends of bones) are still open, meaning growth is still possible.

    If female and 10 years or older, or if menstruation has begun, a pregnancy test will be performed at the beginning of the study. Additional pregnancy tests will be required during the study.

    If sexually active, a highly effective method of contraception (birth control) must be used throughout the study.

  2. Step 2

    Daily medication administration

    The medication used in this study is called vosoritide, which is administered as an injection under the skin (subcutaneous injection).

    The injection will be given once daily.

    A parent or caregiver will be trained to prepare and administer the injection at home.

    The medication comes as a powder that needs to be mixed with a liquid (solvent) before injection.

    The specific dose will be determined based on individual needs and may be 0.4 mg, 0.56 mg, or 1.2 mg.

  3. Step 3

    Regular monitoring visits

    Regular visits will be scheduled throughout the study to monitor progress and safety.

    Height measurements will be taken at each visit to track growth.

    Height will be compared to standard growth charts using a height Z-score, which shows how height compares to other children of the same age.

    Any side effects or health changes will be recorded and evaluated during these visits.

  4. Step 4

    Yearly assessments

    Each year, detailed measurements will be taken to assess how much growth has occurred since the start of the original study.

    These yearly assessments will continue until final adult height is reached, which is when the growth plates have closed and no further growth is possible.

  5. Step 5

    Continuation until final adult height

    The study will continue for as long as growth is still occurring.

    Treatment with vosoritide will be administered daily until final adult height is achieved.

    The total duration of participation will vary for each patient depending on age and growth rate, but the study is expected to run until 2041.

    Safety monitoring will continue throughout the entire treatment period to track any side effects over the long term.

Who can join the trial?

6 criteria

  • The participant must have finished the Week 52 visit in a previous study and still have open growth plates, which are areas of growing tissue near the ends of bones, as checked by an X-ray of the left hand
  • The parent or legal guardian must be willing to sign a consent form after learning about the study and before any study activities begin
  • Female participants who are 10 years old or older, or who have started their menstrual periods, must have a negative pregnancy test at the start of the study and agree to have more pregnancy tests during the study
  • Participants who are sexually active must be willing to use a very effective birth control method while taking part in the study
  • Participants must be willing and able to complete all study activities as much as they physically can
  • The parent or caregiver must be willing to give the participant daily injections, which are shots given with a needle under the skin, and must complete the required training to learn how to do this

Who cannot join the trial?

3 criteria

  • The study document does not provide specific reasons why patients cannot participate in this clinical trial
  • If you are interested in this study, the research team will need to review your complete medical history to determine if you can take part
  • General factors that often prevent participation in clinical trials may include having other serious medical conditions, taking certain medications, or having had specific medical procedures, but these have not been specified for this particular study
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Investigated drugs

Vosoritide is a medication being studied for children with hypochondroplasia, a condition that affects bone growth. This medicine is designed to help children grow taller by working on the way their bones develop. In this study, researchers want to see if vosoritide is safe to use over a long period of time and whether it helps children reach a better final adult height.

What is already known about the treatment

Vosoritide – Vosoritide is a medication given as an injection under the skin (subcutaneous injection) that is used to treat growth problems in children with hypochondroplasia, a genetic condition that affects bone growth and causes short stature. This medicine works at the molecular level by acting like a natural substance in the body called C-type natriuretic peptide, which helps regulate bone growth by activating specific receptors on bone cells, leading to improved bone lengthening. Vosoritide belongs to a class of medications called natriuretic peptide analogs and is currently being studied in long-term clinical trials to evaluate its safety and effectiveness in helping children with hypochondroplasia achieve better growth outcomes until they reach their final adult height.

Investigated diseases

Hypochondroplasia – Hypochondroplasia is a genetic disorder that affects bone growth and development. It is caused by mutations in a specific gene that controls the growth of cartilage and its conversion to bone. People with this condition have shorter than average height, with the shortening more pronounced in the arms and legs compared to the trunk. The condition is present from birth and affects the growth plates in bones, leading to disproportionate short stature. Unlike some other bone growth disorders, the facial features are typically normal or only mildly affected. Hypochondroplasia is considered a rare disease and is milder than some other similar skeletal conditions.
Trial detailsLast updated 2 Oct 2026
Age0-17PhasePhase IIITrial ID2024-517238-16-00Protocol code111-308Estimated enrolment109 patientsSponsorBiomarin Pharmaceutical Inc.

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).