AchondroplasiaPhase 2/3AttaCHNCT05929807
A Clinical Trial to Investigate Long-term Safety, Tolerability, and Efficacy of Weekly Subcutaneous Doses With TransCon CNP in Children and Adolescents With Achondroplasia
A Phase 2/3 study testing TransCon CNP in people with Achondroplasia, run by Ascendis Pharma Growth Disorders A/S at 19 sites in 12 countries.
Trial summary
TransCon CNP administered once-weekly in children and adolescents with achondroplasia who have completed a prior TransCon CNP clinical trial. Participants who complete a prior TransCon CNP trial and meet all eligibility criteria will be invited to continue into the long-term open label extension trial to receive 100… Read more about this study
- Who is it for?
- Ages 3 to 15 years
- Conditions the study is for
- Achondroplasia
- What is being tested?
- TransCon CNP
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 140 participants
- Where
- 19 sitesin 12 countries
- Study dates
- 21 Jun 2023to Mar 2039
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 3 to 15 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Written, signed informed consent of the parent(s) or legal guardian(s) of the participant, and as required by the institutional review board/human research ethics committee/independent ethics committee (IRB/HREC/IEC). For participants who are below the age of consent, a written assent will be obtained in accordance with applicable requirements as required by IRB/HREC/IEC. Upon reaching the legal age of consent, depending on applicable requirements, these participants will be asked to give their own written consent.
- Participants with achondroplasia who have completed a clinical trial with TransCon CNP.
- Parent(s)/legal guardian(s) willing and able to administer weekly SC injections of TransCon CNP and to follow the protocol.
- Considered eligible based on the safety evaluations performed for evaluating stopping/holding rule criteria during the prior TransCon CNP clinical trial.
Who cannot join
- Known or suspected hypersensitivity to the investigational product or related products (trehalose, tris[hydroxymethyl]aminomethane, succinate, and methoxy polyethylene glycol [mPEG]).
- Have received any dose of prescription medications, investigational medicinal product (other than TransCon CNP).
- Sexually active female participants and female partners of male participants of childbearing potential not using a highly effective form of contraceptive (including oral, injectable, or implantable contraception, or intrauterine device (IUD)) for the entire trial period and for 90 days post end of the trial.
- Participants with serum 25-hydroxy-vitamin D (25OHD) levels of <50 nmol/L (<20 ng/mL) at Visit 1 must be on treatment regimen of Vitamin D supplementation.
- Any disease or condition that, in the opinion of the investigator, may make the participant unlikely to fully complete the trial, may confound interpretation of trial results, or may present undue risk from receiving trial treatment. This could include family situations, complications or manifestations, or medications that might impact safety or be considered confounding.
Trial locations and contacts
19 sites in 12 countries. Contact the study team or a site near you to ask about taking part.
19 sites in 12 countries
United States8 sites
Ascendis Investigational Site
Aurora, Colorado, 80045
Ascendis Pharma Investigational Site
Buffalo, New York, 14203
Ascendis Pharma Investigational Site
Columbia Falls, Montana, 65212
Ascendis Investigational Site
Houston, Texas, 77030
Ascendis Pharma Investigational Site
Little Rock, Arkansas, 72202
Ascendis Pharma Investigational Site
Madison, Wisconsin, 53705
Ascendis Investigational Site
Saint Paul, Minnesota, 55102
Ascendis Investigational Site
Wilmington, Delaware, 19803
Australia1 site
Ascendis Pharma Investigational Site
Parkville, Victoria, 3052
About this study
Official title: A Phase 2, Multicenter, Long-Term, Open Label Extension Trial Evaluating Safety, Tolerability, and Efficacy of Subcutaneous Doses of TransCon CNP Administered Once Weekly in Children and Adolescents With Achondroplasia
TransCon CNP administered once-weekly in children and adolescents with achondroplasia who have completed a prior TransCon CNP clinical trial. Participants who complete a prior TransCon CNP trial and meet all eligibility criteria will be invited to continue into the long-term open label extension trial to receive 100 µg CNP/kg/week of TransCon CNP. Trial treatment will be completed when the participant reaches 16 years of age for females and 18 years of age for males and have femur and tibial epiphyseal closure. TransCon CNP treatment will continue if femur and tibial epiphyseal closure is not confirmed at the age of 16 years for females, and 18 years for males. Treatment with TransCon CNP will be completed once femur and tibial epiphyseal closure is confirmed by radiographic imaging. The trial duration is individual for each trial participant. Visits will occur every 12-14 weeks throughout the trial.
- Conditions
- Achondroplasia
- Being tested
- TransCon CNP
- Keywords
- Achondroplasia, Dwarfism
- Medical subject headings
- Achondroplasia, Dwarfism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
TransCon CNPDrug
TransCon CNP drug product is a lyophilized powder in a single-use vial. Prior to use, the lyophilized powder is reconstituted with sterile water for injection and administered by subcutaneous injection via syringe and needle.
| Study group | Role | What they receive |
|---|---|---|
| TransCon CNP 100 mcg | Experimental | TransCon CNP 100 mcg delivered once weekly by subcutaneous injection Receives: Drug: TransCon CNP |
What is being measured
The primary outcome is the main question the study is designed to answer.
Safety and Tolerability
Incidence of Treatment-Emergent Adverse Events
Measured: Through trial completion, an average of 10 years
Height Z-scores
Number of standard deviations
Measured: Through trial completion, an average of 10 years
Secondary outcomes (1)
Annualized Growth Velocity
cm per year
Measured: Through trial completion, an average of 10 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Jul 2023
- Study start21 Jun 2023
- Primary completionJan 2039 (estimated)
- Study completionMar 2039 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AchondroplasiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Patients will roll over from previous TransCON CNP clinical trials
- Masking
- None (open label)
- Enrolment
- 140 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ascendis Pharma Growth Disorders A/S
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, MD, Study director, Ascendis Pharma A/S
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05929807
- Sponsor's protocol ID
- ASND0039
- Acronym
- AttaCH
- Status last verified
- Aug 2026
- First submitted
- 6 Jun 2023
- Last updated
- 17 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 17 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2, Multicenter, Long-Term, Open Label Extension Trial Evaluating Safety, Tolerability, and Efficacy of Subcutaneous Doses of TransCon CNP Administered Once Weekly in Children and Adolescents With Achondroplasia
- ClinicalTrials.gov ID
- NCT05929807
- Acronym / sponsor ID
- AttaCH / ASND0039
- Conditions
- Achondroplasia
- Keywords
- Achondroplasia, Dwarfism
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Enrolling by invitation
- Enrolment
- 140 participants (estimated)
- Lead sponsor
- Ascendis Pharma Growth Disorders A/SIndustry (pharma, biotech, devices)
- Study start
- 21 Jun 2023 (actual)
- Primary completion
- Jan 2039 (estimated)
- Study completion
- Mar 2039 (estimated)
- First posted
- 3 Jul 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
TransCon CNP administered once-weekly in children and adolescents with achondroplasia who have completed a prior TransCon CNP clinical trial. Participants who complete a prior TransCon CNP trial and meet all eligibility criteria will be invited to continue into the long-term open label extension trial to receive 100 µg CNP/kg/week of TransCon CNP. Trial treatment will be completed when the participant reaches 16 years of age for females and 18 years of age for males and have femur and tibial epiphyseal closure. TransCon CNP treatment will continue if femur and tibial epiphyseal closure is not confirmed at the age of 16 years for females, and 18 years for males. Treatment with TransCon CNP will be completed once femur and tibial epiphyseal closure is confirmed by radiographic imaging. The trial duration is individual for each trial participant. Visits will occur every 12-14 weeks throughout the trial.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Patients will roll over from previous TransCON CNP clinical trials
| Arm | Type | Receives |
|---|---|---|
| TransCon CNP 100 mcg | Experimental | Drug: TransCon CNPTransCon CNP 100 mcg delivered once weekly by subcutaneous injection |
Who may qualify
- Ages
- 3 to 15 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (4 listed)
- Written, signed informed consent of the parent(s) or legal guardian(s) of the participant, and as required by the institutional review board/human research ethics committee/independent ethics committee (IRB/HREC/IEC). For participants who are below the age of consent, a written assent will be obtained in accordance with applicable requirements as required by IRB/HREC/IEC. Upon reaching the legal age of consent, depending on applicable requirements, these participants will be asked to give their own written consent.
- Participants with achondroplasia who have completed a clinical trial with TransCon CNP.
- Parent(s)/legal guardian(s) willing and able to administer weekly SC injections of TransCon CNP and to follow the protocol.
- Considered eligible based on the safety evaluations performed for evaluating stopping/holding rule criteria during the prior TransCon CNP clinical trial.
Key exclusion criteria (5 listed)
- Known or suspected hypersensitivity to the investigational product or related products (trehalose, tris[hydroxymethyl]aminomethane, succinate, and methoxy polyethylene glycol [mPEG]).
- Have received any dose of prescription medications, investigational medicinal product (other than TransCon CNP).
- Sexually active female participants and female partners of male participants of childbearing potential not using a highly effective form of contraceptive (including oral, injectable, or implantable contraception, or intrauterine device (IUD)) for the entire trial period and for 90 days post end of the trial.
- Participants with serum 25-hydroxy-vitamin D (25OHD) levels of <50 nmol/L (<20 ng/mL) at Visit 1 must be on treatment regimen of Vitamin D supplementation.
- Any disease or condition that, in the opinion of the investigator, may make the participant unlikely to fully complete the trial, may confound interpretation of trial results, or may present undue risk from receiving trial treatment. This could include family situations, complications or manifestations, or medications that might impact safety or be considered confounding.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| TransCon CNPTransCon CNP drug product is a lyophilized powder in a single-use vial. Prior to use, the lyophilized powder is reconstituted with sterile water for injection and administered by subcutaneous injection via syringe and needle. | Drug | TransCon CNP 100 mcg |
Primary outcome
Safety and Tolerability
Time frame: Through trial completion, an average of 10 years
Incidence of Treatment-Emergent Adverse Events
Height Z-scores
Time frame: Through trial completion, an average of 10 years
Number of standard deviations
1 secondary outcome
Annualized Growth Velocity
Time frame: Through trial completion, an average of 10 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Aug 2026.
- Individual participant dataSharing planned: No
Related trials for Achondroplasia
Enrolling by invitationPhase 2
Extension Study of Infigratinib in Children With Achondroplasia (ACH)
Achondroplasia
RecruitingPhase 2/3
Study to Evaluate the Efficacy and Safety of BMN 333 Versus Vosoritide in Children With Achondroplasia
Achondroplasia
Active, not recruitingPhase 2
A Clinical Trial to Evaluate Efficacy and Safety of Navepegritide in Adolescents (12 - 18 Years of Age) With Achondroplasia.
Achondroplasia
Active, not recruitingPhase 3
Evaluate the Efficacy and Safety of KK8398 in Patients With Achondroplasia（AOBA Study）
Achondroplasia
RecruitingPhase 2
A Study of TYRA-300 in Children With Achondroplasia: BEACH301
Achondroplasia
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Medical Director, MD study director
Ascendis Pharma A/S
19 sites in 12 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing TransCon CNP in people with Achondroplasia, run by Ascendis Pharma Growth Disorders A/S at 19 sites in 12 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 17 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 19 sites in United States, Australia, Austria, Canada, Denmark and 7 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Safety and Tolerability (time frame: Through trial completion, an average of 10 years). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Aug 2026.