Who may be eligible for the A Prospective Sub-Study of the Global Hypophosphatasia Registry trial?

Inclusion Criteria: * 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 Criteria: * 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.

ClinicalTrials.gov record NCT05234567

A Prospective Sub-Study of the Global Hypophosphatasia Registry

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Jul 27, 2026

A Prospective Observational Sub-Study of the Global Hypophosphatasia Registry to Describe the Potential Risk of Immune-Mediated Loss of Pharmacological Effect of Asfotase Alfa in Participants With Hypophosphatasia

About this page. This page shows the study's official ClinicalTrials.gov record ↗, with added help to make it easier to understand. We explain medical terms, highlight key details in plain language, and suggest questions you may want to ask the study team.

The record is periodically copied from ClinicalTrials.gov and may lag behind changes. AI summaries are checked by software, not a clinician.Read moreShow less

The official record is written by the study sponsor and published on ClinicalTrials.gov. It may not always reflect the latest changes. Before making any decisions, please confirm important information with the study team and your own healthcare team.

Where you see "AI summary", AI was used to create a plain-language explanation and software checked it against the source. It has not been reviewed by a clinician, so it may contain mistakes or leave out important details.

StatusRecruitingThe study is currently enrolling participants. Only the study team can say whether a particular person can join.

Study typeObservationalA study in which researchers do not assign participants to a treatment or other intervention. They observe or measure what happens, which may include study visits, tests, questionnaires or a review of medical records.

SexAll

LocationUnited States

AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This prospective observational sub-study follows people with pediatric-onset hypophosphatasia (HPP) for at least five years while they receive asfotase alfa as part of usual care. It is for patients who are receiving asfotase alfa or who will start or resume it within six months; diagnosis requires low alkaline phosphatase and an ALPL gene mutation (an exception may apply for infants who must start treatment immediately). The study collects clinical, laboratory, antibody, imaging, and quality-of-life data to describe immune-mediated loss of drug effect and related serious immune events.

What it is studying. Whether immune responses to asfotase alfa are linked to loss of its pharmacologic effect and to immune-mediated serious adverse events in people with pediatric-onset HPP.

What the researchers hope to learn. To describe the occurrence of immune-mediated loss of effectiveness of asfotase alfa and the occurrence of immune-mediated serious adverse events (including serious hypersensitivity and anaphylaxis) over up to 5 years. To collect biochemical, clinical, imaging, functional, and quality-of-life outcomes relevant to HPP.

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

In this prospective observational sub-study, participants with pediatric-onset hypophosphatasia (HPP) (perinatal/infantile- or juvenile-onset) of any age will be followed for a minimum of 5 years at sites in the United States and potentially 1 or 2 other countries.

Interventions being studied

Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.

Biological: Asfotase Alfa

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

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 criteria

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.

Study description and what participation involves

The registry record has no detailed description beyond the summary above.

AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

Participants receive asfotase alfa by subcutaneous injection according to their physician's standard of care and are followed in this observational sub-study for at least 5 years. The study includes clinical and biochemical assessments, testing for anti-drug and neutralizing antibodies, monitoring for immune-related serious events (such as serious hypersensitivity or anaphylaxis), and imaging only if clinically indicated. Children under 2 years are typically seen about every 3 months until age 2, then about every 6 months; follow-up schedules for others are per the treating physician. Participation may end earlier if a participant withdraws or is withdrawn from the study.

How the study is structured. A prospective, observational (cohort) sub-study of a registry. Participants continue to receive asfotase alfa per their treating physician (the study does not assign treatment). Researchers will collect data from clinic visits, laboratory and antibody tests, imaging if clinically needed, and quality-of-life and functional measures over up to five years. The study will track anti-drug and neutralizing antibodies, clinical and biochemical signs of loss of effect, and immune-mediated serious adverse events.

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

This is an observational study, so the study itself gives no treatment. What would taking part involve for me, and would it change my usual care?
The listed sites are in United States. Is any of them reachable for me, and does the study help with travel?
Which of the eligibility criteria would need to be checked with tests before I could join?

More on hypophosphatasia

Clinical trials9 trials listed for hypophosphatasiaEvery trial the registry lists for hypophosphatasia, with recruitment status, phase and sites, updated from ClinicalTrials.gov.See all trials →Research updatesWhat changed in hypophosphatasia researchLatest monthly update: September 2026. Includes: Early lab flag. New research summarized each month in plain language, with links to every source paper.Read the latest update →

Important dates

Study start: Aug 25, 2022
Primary completion: Jul 18, 2028 (estimated)
Study completion: Jul 18, 2028 (estimated)
Target enrollment: 30 participants (estimated)
Last updated on registry: Feb 9, 2026
Data verified: Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor: Alexion Pharmaceuticals, Inc.

Central study contact

If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.

Alexion Pharmaceuticals, Inc. (Sponsor) 📞 1-855-752-2356 ✉ clinicaltrials@alexion.com

Participating sites (12)

Clinical Trial SiteRecruiting
Hartford, Connecticut, 06106 · United States
Clinical Trial SiteRecruiting
Chicago, Illinois, 60611 · United States
Clinical Trial SiteRecruiting
Boston, Massachusetts, 02122 · United States
Clinical Trial SiteRecruiting
Kansas City, Missouri, 64108 · United States
Clinical Trial SiteRecruiting
Mineola, New York, 11501 · United States
Clinical Trial SiteNot Yet Recruiting
Cincinnati, Ohio, 45229 · United States
Clinical Trial SiteRecruiting
Columbus, Ohio, 43203 · United States
Clinical Trial SiteNot Yet Recruiting
Pittsburgh, Pennsylvania, 15224 · United States
Clinical Trial SiteRecruiting
Nashville, Tennessee, 37112 · United States
Clinical Trial SiteRecruiting
Salt Lake City, Utah, 84108 · United States

Terms used on this page · explanations by MedicalUpdates.ai

Enrollment: The number of participants a study plans to include, or has included. 'Estimated' means the planned number; 'actual' means the number who joined.
treatment-naïve: Has not previously received the treatment, or the type of treatment, that the study is about.
legally authorized representative: A person who is legally allowed to make decisions, including consent to research, on behalf of someone who cannot consent for themselves.
informed consent: The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
assent: A child's or dependent adult's agreement to take part, given alongside the formal consent of a parent or legal representative.
interventional: A study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.
Inclusion Criteria: The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
Exclusion Criteria: The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

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