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Observational Study of Asfotase Alfa for Pediatric-Onset Hypophosphatasia

This is an observational study looking at how people with pediatric-onset hypophosphatasia (HPP), a rare bone disease, respond to treatment with asfotase alfa. All participants will receive asfotase alfa as part of their regular care. Researchers want to understand if the treatment causes the body to develop an immune response that makes the medicine less effective or leads to serious side effects. You can join if you have a confirmed diagnosis of pediatric-onset HPP and are currently receiving asfotase alfa, or your doctor plans to start or restart it soon. This study aims to follow 30 participants for up to 5 years. The current recruitment status is unclear.

Study design
This is an observational study with no specified phase, following 30 participants. It is not randomized or blinded.
What's involved
If you are under 2 years old, you may have clinic visits about every 3 months until you turn 2. The study will follow you for a minimum of 5 years.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed for up to 5 years to monitor for immune-mediated loss of effectiveness and serious adverse events.

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NCT05234567

A Prospective Sub-Study of the Global Hypophosphatasia Registry

Recruiting
Not specifiedAll AgesObservational
Alexion Pharmaceuticals, Inc.
~30 participants
Updated 2026-02-09 on ClinicalTrials.gov
What's tested:Asfotase Alfa

At a glance

Recruiting sites
10 of 12 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Occurrence Of Immune-mediated Loss Of Effectiveness According To The Treating Physician
Measured over Up to 5 years
+1 more outcome measured

Conditions

Hypophosphatasia

Explore related trials

HypophosphatasiaAlkaline PhosphataseALPL Gene

Where it's being run

12 sites across 11 states
Ohio2
Connecticut1
Illinois1
Massachusetts1
Missouri1
New York1
Pennsylvania1
Tennessee1

Who to contact

Alexion Pharmaceuticals, Inc. (Sponsor)
[email protected]
1-855-752-2356
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Eligibility criteria

Inclusion

Any age or sex with a confirmed diagnosis of pediatric-onset HPP (that is, first HPP sign or symptom presented at \< 18 years of age).
Currently receiving asfotase alfa treatment at Enrollment (not treatment-naïve) or the Physician has decided to resume (not treatment-naïve) or start (treatment-naïve) the participant's asfotase alfa treatment within 6 months after Enrollment.
Participant must have documented alkaline phosphatase (ALP) activity below the lower limit of normal for age and sex, and a documented ALPL gene mutation (Note: An exception is made for infants with clinical features of HPP plus low ALP who need to start asfotase alfa treatment right away, at the Physician's discretion, but do not yet have a genetic result. In this case, ALPL gene documentation is not required at the time of sub-study enrollment but should be documented within 6 months after Enrollment).
Participant or participant's parent/legally authorized representative is able to read and/or understand the informed consent and study questionnaires in the local language.
Participant or participant's parent/legally authorized representative must be willing and able to give signed informed consent for this sub-study, and the participant must be willing to give written informed assent, if appropriate and required by local regulations.

Exclusion

Currently participating in an Alexion-sponsored interventional clinical study. Participants who have concluded participation in an Alexion-sponsored asfotase alfa clinical study are eligible to enroll in this sub-study.

What this trial measures

  • Occurrence Of Immune-mediated Loss Of Effectiveness According To The Treating PhysicianUp to 5 years

    This will be based on clinical and biochemical assessments as well as positive anti-drug antibodies and positive neutralizing antibodies.

  • Occurrence Of Immune-mediated Serious Adverse EventsUp to 5 years

    These serious adverse events will include serious hypersensitivity reactions and anaphylaxis.