ClinicalTrials.gg
Enrolling by invitationNCT05929807AttaCHUpdated Aug 17, 2026

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 interventional study of TransCon CNP in Achondroplasia, sponsored by Ascendis Pharma Growth Disorders A/S. Enrolling by invitation at 19 sites in 12 countries. Open to participants aged 3 Years to 15 Years. Per ClinicalTrials.gov, last updated 2026-08-17.

Sponsored by Ascendis Pharma Growth Disorders A/S · Phase 2/3, Interventional, and Treatment

Phase
Phase 2/3
Study type
Interventional
Enrollment
140
Allocation
Not applicable
Ages
3 Years to 15 Years
Sex
All
01

Study 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 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.

02

Conditions studied

  • Achondroplasia

Keywords

  • Achondroplasia
  • Dwarfism
03

In context

Achondroplasia

47 studies on the registry are indexed under Achondroplasia; 13 are open to participants now.

This study's planned enrollment of 140 is above the median of 74 across 28 interventional studies indexed under Achondroplasia.

Browse Achondroplasia studies →

Lead sponsor

Ascendis Pharma Growth Disorders A/S is the lead sponsor of 3 studies on the registry; 1 is open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
3 Years to 15 Years
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • Written, signed 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.

Exclusion criteria

Exclusion Criteria:

  • Known or suspected to the 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 not using a highly effective form of (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.
Terms in these criteria, in plain language(5)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

05

Study design

Phase
Phase 2 / Phase 3
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
140 participants (estimated)

Study arms

  • Experimental
    TransCon CNP 100 mcg

    TransCon CNP 100 mcg delivered once weekly by subcutaneous injection

    Drug: TransCon CNP

Interventions

  • 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.

06

What researchers measure

Primary outcomes

  1. Safety and Tolerability

    Incidence of Treatment-Emergent Adverse Events

    Time frame: Through trial completion, an average of 10 years

  2. Height Z-scores

    Number of standard deviations

    Time frame: Through trial completion, an average of 10 years

Secondary outcomes

  1. Annualized Growth Velocity

    cm per year

    Time frame: Through trial completion, an average of 10 years

07

Study locations

19 sites
  • Ascendis Pharma Investigational Site
    Little Rock, Arkansas 72202, United States
  • Ascendis Investigational Site
    Aurora, Colorado 80045, United States
  • Ascendis Investigational Site
    Wilmington, Delaware 19803, United States
  • Ascendis Investigational Site
    Saint Paul, Minnesota 55102, United States
  • Ascendis Pharma Investigational Site
    Columbia Falls, Montana 65212, United States
  • Ascendis Pharma Investigational Site
    Buffalo, New York 14203, United States
  • Ascendis Investigational Site
    Houston, Texas 77030, United States
  • Ascendis Pharma Investigational Site
    Madison, Wisconsin 53705, United States
  • Ascendis Pharma Investigational Site
    Parkville, Victoria 3052, Australia
  • Ascendis Investigational Site
    Linz, 4020, Austria
  • Ascendis Investigational Site
    Montreal, H3T 1C5, Canada
  • Ascendis Pharma Investigational Site
    Copenhagen, 2100, Denmark
  • Ascendis Pharma Investigational Site
    Paris, 75743, France
  • Ascendis Investigational Site
    Berlin, 13353, Germany
  • Ascendis Pharma Investigational Site
    Dublin, D01 YC76, Ireland
  • Ascendis Investigational Site
    Auckland, 1023, New Zealand
  • Ascendis Investigational Site
    Coimbra, 3000-602, Portugal
  • Ascendis Investigational Site
    Vitoria-Gasteiz, 1008, Spain
  • Ascendis Investigational Site
    London, SE1 7EH, United Kingdom
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Started Jun 2023 (actual). Primary completion is estimated for Jan 2039, 187 months after the start.

How these figures are worked out, and which studies are left out of them.

Registered
Jun 6, 2023
First posted
Jul 3, 2023
StartActual
Jun 21, 2023
Primary completionEst.
Jan 2039
CompletionEst.
Mar 2039
Last update
Aug 17, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Aug 17, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT05929807
Lead sponsor
Ascendis Pharma Growth Disorders A/S
Responsible party
Sponsor
First posted
Jul 3, 2023
Start date
Jun 21, 2023
Primary completion
Jan 2039 (estimated)
Completion
Mar 2039 (estimated)
Last update
Aug 17, 2026

Study contacts

Medical Director, MD
study director · Ascendis Pharma A/S

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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No contact was published for this record. The registry link below has the sponsor’s details.

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Studies of the drug tested here: Navepegritide

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