ALXN1850-HPP-305 - Mulberry - ALXN1850 vs Placebo in Asfotase Alfa Naive Paediatric Pts with HPP

  • Research type

    Research Study

  • Full 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.



  • Contact name

    Per Gustafsson

  • Contact email

  • Sponsor organisation

    Alexion Pharmaceuticals, Inc.

  • Identifier


  • Research summary

    The purpose of this study is to assess if the study drug (ALXN1850) works better than placebo when given to participants (2 to less than 12 years of age) with hypophosphatasia (HPP) who have not received Asfotase Alfa (Strensiq®) before. To evaluate how well ALXN1850 works, functional outcomes & radiographic changes will be measured. The study also aims to assess, but not limited to:
    - Side effects of ALXN1850 and how often they happen, and the severity of side effects compared to placebo.
    - What the body does to ALXN1850 (pharmacokinetics) and what ALXN1850 does to the body (pharmacodynamics),
    - Evaluate health quality of life outcomes based on health questionnaire completion by the participants/caregiver and whether ALXN1850 triggers an immune response.
    Strensiq® is the only approved treatment for HPP for paediatric onset patients (those who develop the condition at an early age before adulthood). ALXN1850 has been developed to address the unmet needs of Strensiq®, which are to increase drug exposure & make enzyme activity more efficient, thereby enabling study drug dosing at lower volumes and less frequently.
    This study consists of 4 phases, Screening, Randomised Evaluation period (REP), an Open label Extension (OLE) & Safety Follow Up. Participants who meet the study eligibility criteria during the screening phase will have a 2/3 and 1/3 chance of receiving ALXN1850 or placebo respectively. During REP, all participants will be randomly assigned to receive study intervention (ALXN1850 or placebo) starting on Day 1 and thereafter for a total of 24 weeks. The ALXN1850 group will receive a body weight-based dose of ALXN1850 every 2 weeks via subcutaneous (SC) injection. The placebo group will receive placebo every 2 weeks via SC injection. All participants will be offered ALXN1850 every 2 weeks in the OLE. The total study duration is approximately 164 weeks (just over 3 years). Approximately 30 participants globally will be enrolled in this study.

  • REC name

    South Central - Berkshire Research Ethics Committee

  • REC reference


  • Date of REC Opinion

    1 Feb 2024

  • REC opinion

    Further Information Favourable Opinion