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

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What is this study about?

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.

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 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 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 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 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 Study?

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 Study?

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

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Fondazione Policlinico Universitario Agostino Gemelli IRCCS	Rome	Italy
Hopital Necker Enfants Malades	Paris	France

Other Sites

Site Name	City	Country
Hopital Des Enfants	Toulouse	France
IRCCS Istituto Giannina Gaslini	Genoa	Italy
Centre Hospitalier Lyon Sud	Pierre Benite	France
Ospedale Pediatrico Bambino Gesu’	Rome	Italy
Otto Von Guericke Universitaet Magdeburg	Magdeburg	Germany
Apbvojchxz Ppostldz Hpcxljan De Mqmwigdvr	Marseille	France
Uqyolhceds Hxhicxza Chclpto	Cologne	Germany

Trial status

Country	Status	Recruitment Start
France	Recruiting	09.01.2026
Germany	Recruiting	09.01.2026
Italy	Recruiting	09.01.2026
Spain	Recruiting	09.01.2026

Trial locations

Investigated drugs:

Vosoritide

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.

Investigated diseases:

Hypochondroplasia

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 ID:

2024-517238-16-00

Protocol code:

111-308

Trial Phase:

Therapeutic confirmatory (Phase III)

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

What is this study about?

Who Can Join the Study?

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