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NCT Number: NCT06079359

Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPP

The primary purpose of this study is to evaluate the efficacy of ALXN1850 versus placebo on radiographic outcomes in pediatric participants with HPP who have not previously been treated with asfotase alfa.

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This study is active but is not currently recruiting participants.

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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, Nedlands, Australia

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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, and the following criteria fulfilled without other probable cause than HPP:
  • Presence of HPP-related rickets on skeletal X-rays during the Screening Period, with a minimum Rickets Severity Score (RSS) of 1.0 AND
  • Serum ALP activity below the age- and sex-adjusted normal range during the Screening Period as measured by the Central Laboratory OR 2 documented serum ALP activity results, at least 15 days apart, below the age- and sex-adjusted local laboratory normal range during the 24 months before the Day 1 Visit. Note: Local laboratories need to be Clinical Laboratory Improvement Amendments (CLIA) or ISO 15189 certified, or have other local equivalent laboratory certification with Alexion's approval.
  • Must meet 1 of the following criteria:
  • Documented ALPL gene variant (pathogenic, likely pathogenic, or variant of unknown significance) from a CLIA certified laboratory (Section 8.7)
  • Plasma PLP above the upper limit of normal (ULN) during the Screening Period (central or local laboratory results allowed per local regulations)
  • Tanner stage 2 or less during the Screening Period

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 ALXN1850 or the placebo comparator

Treatment and study plan

ALXN1850

Drug

Participants will receive a ALXN1850 via subcutaneous (SC) injection.

Placebo

Drug

Participants will receive placebo via SC injection.

Primary outcomes

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

    Time frame: Day 169

Secondary outcomes

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

    Time frame: Baseline, Day 169

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

    Time frame: Baseline, Day 169

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

    Time frame: Baseline, Day 169

  4. 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

  5. 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

  6. RGI-C Responder at the end of the Randomized Evaluation Period (Day 169)

    Time frame: Day 169

Sponsors and collaborators

Lead sponsor

Alexion Pharmaceuticals, Inc.

Industry

Registry information

Official study title

A Phase 3, Randomized, Double-blinded, Placebo-controlled, Multicenter Study to Evaluate Efficacy and Safety of ALXN1850 Versus Placebo Administered Subcutaneously in Pediatric (2 to < 12 Years of Age) Participants With Hypophosphatasia Who Have Not Received Previous Treatment With Asfotase Alfa

Acronym: MULBERRY

Important dates

Study start
2024
Primary completion
2026
Study completion
2028
First posted
Oct 12, 2023
Registry last updated
May 28, 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.

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