HypophosphatasiaNCT05234567
A Prospective Sub-Study of the Global Hypophosphatasia Registry
An observational study of Hypophosphatasia, run by Alexion Pharmaceuticals, Inc. at 12 sites in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Hypophosphatasia
- What is being tested?
- Asfotase Alfa
- Type of treatment
- Injection or infusion
- How many people
- 30 participants
- Where
- 12 sitesUnited States
- Study dates
- 25 Aug 2022to 18 Jul 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Patients with HPP
Who may be able to join
- 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.
Who cannot join
- 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.
Trial locations and contacts
12 sites in 1 country. Contact the study team or a site near you to ask about taking part.
12 sites in 1 country
United States12 sites, 12 recruiting
- Recruiting
Clinical Trial Site
Boston, Massachusetts, 02122
- Recruiting
Clinical Trial Site
Charlottesville, Virginia, 22903
- Recruiting
Clinical Trial Site
Chicago, Illinois, 60611
- Not yet recruiting
Clinical Trial Site
Cincinnati, Ohio, 45229
- Recruiting
Clinical Trial Site
Columbus, Ohio, 43203
- Recruiting
Clinical Trial Site
Hartford, Connecticut, 06106
- Recruiting
Clinical Trial Site
Kansas City, Missouri, 64108
- Recruiting
Clinical Trial Site
Madison, Wisconsin, 53792
- Recruiting
Clinical Trial Site
Mineola, New York, 11501
- Recruiting
Clinical Trial Site
Nashville, Tennessee, 37112
- Not yet recruiting
Clinical Trial Site
Pittsburgh, Pennsylvania, 15224
- Recruiting
Clinical Trial Site
Salt Lake City, Utah, 84108
About this study
Official title: 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
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.
- Conditions
- Hypophosphatasia
- Being tested
- Asfotase Alfa
- Keywords
- Pediatric Onset, HPP, Asfotase alfa
- Medical subject headings
- Hypophosphatasia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Asfotase AlfaBiological
Also called Strensiq
All participants will receive asfotase alfa subcutaneously per standard of care. Unless otherwise specified per the Physician's standard of care, participants aged < 2 years are recommended for a clinic visit approximately every 3 months after Enrollment until 2 years of age, after which they should have a clinic visit approximately every 6 months. Participants should be followed for 5 years, as possible.
| Study group | Role | What they receive |
|---|---|---|
| Participants with Pediatric-onset HPP | Each participant will be followed for a minimum of 5 years or, if applicable, until early withdrawal. Biochemical, clinical, imaging (if clinically indicated), and functional/quality of life outcomes relevant to HPP will be assessed. Receives: Biological: Asfotase Alfa |
What is being measured
The primary outcome is the main question the study is designed to answer.
Occurrence Of Immune-mediated Loss Of Effectiveness According To The Treating Physician
This will be based on clinical and biochemical assessments as well as positive anti-drug antibodies and positive neutralizing antibodies.
Measured: Up to 5 years
Occurrence Of Immune-mediated Serious Adverse Events
These serious adverse events will include serious hypersensitivity reactions and anaphylaxis.
Measured: Up to 5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Feb 2022
- Study start25 Aug 2022
- Primary completion18 Jul 2028 (estimated)
- Study completion18 Jul 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HypophosphatasiaStudies of the same condition, open and under way.
- More trials run by Alexion Pharmaceuticals, Inc.The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Alexion Pharmaceuticals, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05234567
- Sponsor's protocol ID
- ALX-HPP-501s
- Status last verified
- Feb 2026
- First submitted
- 1 Feb 2022
- Last updated
- 9 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.
Study at a glance
From the registry record, last updated by the sponsor on 9 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT05234567
- Acronym / sponsor ID
- ALX-HPP-501s
- Conditions
- Hypophosphatasia
- Keywords
- Pediatric Onset, HPP, Asfotase alfa
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Alexion Pharmaceuticals, Inc.Industry (pharma, biotech, devices)
- Study start
- 25 Aug 2022 (actual)
- Primary completion
- 18 Jul 2028 (estimated)
- Study completion
- 18 Jul 2028 (estimated)
- First posted
- 10 Feb 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Participants with Pediatric-onset HPP | – | Biological: Asfotase AlfaEach participant will be followed for a minimum of 5 years or, if applicable, until early withdrawal. Biochemical, clinical, imaging (if clinically indicated), and functional/quality of life outcomes relevant to HPP will be assessed. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Patients with HPP
Key inclusion criteria (5 listed)
- 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.
Key exclusion criteria (1 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Asfotase AlfaAlso: StrensiqAll participants will receive asfotase alfa subcutaneously per standard of care. Unless otherwise specified per the Physician's standard of care, participants aged < 2 years are recommended for a clinic visit approximately every 3 months after Enrollment until 2 years of age, after which they should have a clinic visit approximately every 6 months. Participants should be followed for 5 years, as possible. | Biological | Participants with Pediatric-onset HPP |
Primary outcome
Occurrence Of Immune-mediated Loss Of Effectiveness According To The Treating Physician
Time frame: Up 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 Events
Time frame: Up to 5 years
These serious adverse events will include serious hypersensitivity reactions and anaphylaxis.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Feb 2026.
- Individual participant dataSharing planned: Yes. Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
12 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Hypophosphatasia, run by Alexion Pharmaceuticals, Inc. at 12 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 12 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Alexion Pharmaceuticals, Inc. (Sponsor) (1-855-752-2356, clinicaltrials@alexion.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Occurrence Of Immune-mediated Loss Of Effectiveness According To The Treating Physician (time frame: Up to 5 years). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Feb 2026.