Skip to main content
OpenTrials
Active, Not Recruiting

NCT Number: NCT06079372

Phase 3 Study of ALXN1850 in Pediatric Participants With HPP Previously Treated With Asfotase Alfa

The primary purpose of this study is to assess the safety and tolerability of ALXN1850 versus asfotase alfa in pediatric participants with HPP previously treated with asfotase alfa.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Hypophosphatasia Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Metabolic Diseases Metabolism, Inborn Errors Metal Metabolism, Inborn Errors Nutritional and Metabolic Diseases

Age range

2 year–11 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Research Site, Mar del Plata, Argentina

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Diagnosis of HPP documented in the medical records
  • Presence of open growth plates by X-ray during Screening Period
  • Tanner stage 2 or less during the Screening Period
  • Must have been treated with 6 mg/kg/ week of asfotase alfa via SC injection administered as either 2mg/kg 3 times per week or 1 mg/kg 6 times per week for ≥ 6 months before Day 1. Note: participants currently treated with 9 mg/kg (eg, 3 mg/kg 3 times per week) will not be allowed in the study.

Exclusion criteria

  • History or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrinological, hematological, neurological disorders, or any other disorders that are capable of significantly altering the absorption, metabolism, or elimination of drugs; constituting a risk when taking the study intervention; or interfering with the interpretation of data as determined by the Investigator.
  • Diagnosis of primary or secondary hyperparathyroidism
  • Hypoparathyroidism, unless secondary to HPP
  • Any new fracture within 12 weeks before Day 1 (excluding pseudofractures)
  • Planned surgical intervention which may impact the results of study assessments (in the opinion of the Investigator) during the Randomized Evaluation Period
  • History of allergy or hypersensitivity to any ingredient contained in asfotase alfa or ALXN1850
  • Body weight < 10 kg during the Screening Period

Treatment and study plan

ALXN1850

Drug

ALXN1850 will be administered via subcutaneous (SC) injection.

asfotase alfa

Drug

Asfotase alfa will be administered via SC injection.

Primary outcomes

  1. Number of Participants with Treatment-emergent Adverse Events (TEAEs)

    Time frame: Baseline Through Day 169

Secondary outcomes

  1. Radiographic Global Impression of Change (RGI-C) Score at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

  2. Change from Baseline in Rickets Severity Score (RSS) at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

  3. Change from Baseline in 6-Minute Walk Test (6MWT) at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

  4. Change from Baseline in Percent Predicted 6MWT at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

  5. Change from Baseline in Bruininks Oseretsky Test of Motor Proficiency, Second Edition (BOT2) Score at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

  6. Change from Baseline in Peabody Developmental Motor Scales, Third Edition (PDMS-3) Score at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Baseline, Day 169

Sponsors and collaborators

Lead sponsor

Alexion Pharmaceuticals, Inc.

Industry

Registry information

Official study title

A Phase 3, Randomized, Open-label, Parallel-arm, Active-controlled, Multicenter Study to Evaluate Safety and Efficacy of ALXN1850 Versus Asfotase Alfa Administered Subcutaneously in Pediatric Participants (2 to < 12 Years of Age) With Hypophosphatasia (HPP) Previously Treated With Asfotase Alfa

Acronym: CHESTNUT

Important dates

Study start
2024
Primary completion
2025
Study completion
2028
First posted
Oct 12, 2023
Registry last updated
May 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.