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

NCT06079359 | Active Not Recruiting Phase 3 DMC FDA Drug

• 2 other identifiers: D8590C00003ALXN1850-HPP-305
• Study Type: interventional
• Target: 30
• Locations: 16 countries
• Sites: 32

Brief Summary

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.

Conditions

Hypophosphatasia

Keywords

Hypophosphatasia; HPP; ALXN1850

Outcome Measures

Primary Outcomes (1)

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

  Day 169

Secondary Outcomes (6)

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

  Baseline, Day 169

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

  Baseline, Day 169

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

  Baseline, Day 169

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

  Baseline, Day 169

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

  Baseline, Day 169

Study Arms (2)

ALXN1850

EXPERIMENTAL

Starting at Day 1 of the Randomized Evaluation Period, the ALXN1850 group will receive bodyweight dependent doses of either 20mg, 35mg or 50mg of ALXN1850 once every 2 weeks (q2w) via SC injection, for 24 weeks. Participants will enter the OLE Period and continue q2w dosing with ALXN1850 for up to 132 weeks.

Drug: ALXN1850; Drug: Placebo

Placebo

PLACEBO COMPARATOR

Starting at Day 1 during the Randomized Evaluation Period, participants will receive placebo q2w for a total of 24 weeks. Participants will enter the OLE Period and continue q2w dosing with ALXN1850 for up to 132 weeks.

Drug: Placebo

Interventions

ALXN1850 DRUG

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

ALXN1850

Placebo DRUG

Participants will receive placebo via SC injection.

ALXN1850; Placebo

Eligibility Criteria

• Age: 2 Years - 11 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Alexion Pharmaceuticals, Inc.: lead

Study Sites (32)

Research Site

Baltimore, Maryland, 21287, United States

Location

Research Site

Kansas City, Missouri, 64108, United States

Location

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Durham, North Carolina, 27705, United States

Location

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Nedlands, 6009, Australia

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Parkville, 3052, Australia

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Brussels, 1020, Belgium

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Brasília, 71625-009, Brazil

Location

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Porto Alegre, 90610-261, Brazil

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Recife, 50740-465, Brazil

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Salvador, 40050-410, Brazil

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São Paulo, 01409-902, Brazil

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São Paulo, 05403-900, Brazil

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Calgary, Alberta, T2E 7H7, Canada

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Winnepeg, Manitoba, R3E 3P4, Canada

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Beijing, 100045, China

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Guangzhou, 510623, China

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Shanghai, 2000127, China

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Shenzhen, 518053, China

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Helsinki, 00290, Finland

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Ashkelon, 7830604, Israel

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Chihuahua City, 31238, Mexico

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Lodz, 93-338, Poland

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Bucharest, 011863, Romania

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Madrid, 28046, Spain

Location

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Vitoria-Gasteiz, 01009, Spain

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Stockholm, 17176, Sweden

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Taipei, 100, Taiwan

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Ankara, 06560, Turkey (Türkiye)

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Bursa, 16059, Turkey (Türkiye)

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Erzurum, 25240, Turkey (Türkiye)

Location

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Istanbul, 34899, Turkey (Türkiye)

Location

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Birmingham, B4 6NH, United Kingdom

Location

MeSH Terms

Conditions

Hypophosphatasia

Condition Hierarchy (Ancestors)

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

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: double-blinded
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 6, 2023
• First Posted: October 12, 2023
• Study Start: May 14, 2024
• Primary Completion: January 6, 2026
• Study Completion (Estimated): August 24, 2028
• Last Updated: May 28, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, CSR

Locations

ME (1); RO (1); AU (2); BE (1); FI (1); BR (6); PL (1); SE (1); TU (4); CA (2); CN (4); US (3); GB (1); TW (1); ES (2); IL (1)