A Clinical Trial to Investigate Long-term Safety, Tolerability, and Efficacy of Weekly Subcutaneous Doses With TransCon CNP in Children and Adolescents With Achondroplasia

NCT05929807 | Enrolling By Invitation Phase 2 DMC FDA Drug

• 1 other identifier: ASND0039
• Study Type: interventional
• Target: 140
• Locations: 9 countries
• Sites: 16

Brief 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.

Conditions

Achondroplasia

Keywords

Achondroplasia; Dwarfism

Outcome Measures

Primary Outcomes (2)

• Safety and Tolerability

  Incidence of Treatment-Emergent Adverse Events

  Through trial completion, an average of 10 years

• Height Z-scores

  Number of standard deviations

  Through trial completion, an average of 10 years

Secondary Outcomes (1)

• Annualized Growth Velocity

  Through trial completion, an average of 10 years

Study Arms (1)

TransCon CNP 100 mcg

EXPERIMENTAL

TransCon CNP 100 mcg delivered once weekly by subcutaneous injection

Drug: TransCon CNP

Interventions

TransCon CNP DRUG

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.

TransCon CNP 100 mcg

Eligibility Criteria

• Age: 3 Years - 15 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Ascendis Pharma Growth Disorders A/S: lead

Study Sites (17)

Ascendis Pharma Investigational Site

Little Rock, Arkansas, 72202, United States

Location

Ascendis Investigational Site

Aurora, Colorado, 80045, United States

Location

Ascendis Investigational Site

Wilmington, Delaware, 19803, United States

Location

Ascendis Investigational Site

Saint Paul, Minnesota, 55102, United States

Location

Ascendis Pharma Investigational Site

Columbia Falls, Montana, 65212, United States

Location

Ascendis Pharma Investigational Site

Buffalo, New York, 14203, United States

Location

Ascendis Investigational Site

Houston, Texas, 77030, United States

Location

Ascendis Pharma Investigational Site

Madison, Wisconsin, 53705, United States

Location

Ascendis Pharma Investigational Site

Parkville, Victoria, 3052, Australia

Location

Ascendis Investigational Site

Linz, 4020, Austria

Location

Ascendis Investigational Site

Montreal, H3T 1C5, Canada

Location

Ascendis Pharma Investigational Site

Copenhagen, 2100, Denmark

Location

Ascendis Investigational Site

Berlin, 13353, Germany

Location

Ascendis Pharma Investigational Site

Dublin, D01 YC76, Ireland

Location

Ascendis Investigational Site

Auckland, 1023, New Zealand

Location

Ascendis Investigational Site

Coimbra, 3000-602, Portugal

Location

Ascendis Investigational Site

Vitoria-Gasteiz, 1008, Spain

Location

MeSH Terms

Conditions

Achondroplasia; Dwarfism

Condition Hierarchy (Ancestors)

Bone Diseases, Developmental; Bone Diseases; Musculoskeletal Diseases; Osteochondrodysplasias; Genetic Diseases, Inborn; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Endocrine System Diseases

Study Officials

• Claus Strange

  Ascendis Pharma A/S

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Patients will roll over from previous TransCON CNP clinical trials

Study Record Dates

• First Submitted: June 6, 2023
• First Posted: July 3, 2023
• Study Start: June 21, 2023
• Primary Completion (Estimated): January 1, 2039
• Study Completion (Estimated): March 1, 2039
• Last Updated: October 27, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will not share

Locations

NZ (1); DE (1); AU (1); US (8); ES (1); DK (1); CA (1); IE (1); PT (1)