HypophosphatasiaPhase 3MULBERRYNCT06079359
Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPP
A Phase 3 study testing ALXN1850 in people with Hypophosphatasia, run by Alexion Pharmaceuticals, Inc. at 32 sites in 16 countries.
Trial 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. Read more about this study
- Who is it for?
- Ages 2 to 11 years
- Conditions the study is for
- Hypophosphatasia
- What is being tested?
- ALXN1850
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 32 sitesin 16 countries
- Study dates
- 14 May 2024to 24 Aug 2028
- Phase
- Phase 3
- 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 2 to 11 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
32 sites in 16 countries.
32 sites in 16 countries
Brazil6 sites
Research Site
Brasília, 71625-009
Research Site
Porto Alegre, 90610-261
Research Site
Recife, 50740-465
Research Site
Salvador, 40050-410
Research Site
São Paulo, 01409-902
Research Site
São Paulo, 05403-900
China4 sites
Research Site
Beijing, 100045
Research Site
Guangzhou, 510623
Research Site
Shanghai, 2000127
Research Site
Shenzhen, 518053
Turkey (Türkiye)4 sites
Research Site
Ankara, 06560
Research Site
Bursa, 16059
Research Site
Erzurum, 25240
Research Site
Istanbul, 34899
United States3 sites
Research Site
Baltimore, Maryland, 21287
Research Site
Durham, North Carolina, 27705
Research Site
Kansas City, Missouri, 64108
Canada2 sites
Research Site
Calgary, Alberta, T2E 7H7
Research Site
Winnepeg, Manitoba, R3E 3P4
About this study
Official 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
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
- Being tested
- ALXN1850, Placebo
- Keywords
- Hypophosphatasia, HPP, ALXN1850
- Medical subject headings
- Hypophosphatasia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ALXN1850Drug
Participants will receive a ALXN1850 via subcutaneous (SC) injection.
PlaceboDrug
Participants will receive placebo via SC injection.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Radiographic Global Impression of Change (RGI-C) Score at the end of the Randomized Evaluation Period (Day 169)
Measured: Day 169
Secondary outcomes (6)
Change from Baseline in Rickets Severity Score (RSS) at the end of the Randomized Evaluation Period (Day 169)
Measured: Baseline, Day 169
Change from Baseline in 6-Minute Walk Test (6MWT) at the end of the Randomized Evaluation Period (Day 169)
Measured: Baseline, Day 169
Change from Baseline in Percent Predicted 6MWT at the end of the Randomized Evaluation Period (Day 169)
Measured: 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)
Measured: 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)
Measured: Baseline, Day 169
RGI-C Responder at the end of the Randomized Evaluation Period (Day 169)
Measured: Day 169
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Oct 2023
- Study start14 May 2024
- Primary completion6 Jan 2026
- Study completion24 Aug 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
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- Alexion Pharmaceuticals, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06079359
- Sponsor's protocol ID
- D8590C00003
- Other IDs
- ALXN1850-HPP-305
- Acronym
- MULBERRY
- Status last verified
- May 2026
- First submitted
- 6 Oct 2023
- Last updated
- 28 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- 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 28 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official 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
- ClinicalTrials.gov ID
- NCT06079359
- Acronym / sponsor ID
- MULBERRY / D8590C00003
- Conditions
- Hypophosphatasia
- Keywords
- Hypophosphatasia, HPP, ALXN1850
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 30 participants (actual)
- Lead sponsor
- Alexion Pharmaceuticals, Inc.Industry (pharma, biotech, devices)
- Study start
- 14 May 2024 (actual)
- Primary completion
- 6 Jan 2026 (actual)
- Study completion
- 24 Aug 2028 (estimated)
- First posted
- 12 Oct 2023 (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.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| ALXN1850 | Experimental | Drug: ALXN1850, Drug: PlaceboStarting 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. |
| Placebo | Placebo comparator | Drug: PlaceboStarting 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. |
Who may qualify
- Ages
- 2 to 11 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (7 listed)
- Diagnosis of HPP documented in the medical records, and the following criteria fulfilled without other probable cause than HPP:
- Must meet 1 of the following criteria:
- Tanner stage 2 or less during the Screening Period
Key exclusion criteria (6 listed)
- 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
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 |
|---|---|---|
| ALXN1850Participants will receive a ALXN1850 via subcutaneous (SC) injection. | Drug | ALXN1850 |
| PlaceboParticipants will receive placebo via SC injection. | Drug | ALXN1850, Placebo |
Primary outcome
Radiographic Global Impression of Change (RGI-C) Score at the end of the Randomized Evaluation Period (Day 169)
Time frame: Day 169
6 secondary outcomes
Change from Baseline in Rickets Severity Score (RSS) at the end of the Randomized Evaluation Period (Day 169)
Time frame: Baseline, Day 169
Change from Baseline in 6-Minute Walk Test (6MWT) at the end of the Randomized Evaluation Period (Day 169)
Time frame: Baseline, Day 169
Change from Baseline in Percent Predicted 6MWT at the end of the Randomized Evaluation Period (Day 169)
Time frame: 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)
Time frame: 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)
Time frame: Baseline, Day 169
RGI-C Responder at the end of the Randomized Evaluation Period (Day 169)
Time frame: Day 169
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 28 May 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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
32 sites in 16 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing ALXN1850 in people with Hypophosphatasia, run by Alexion Pharmaceuticals, Inc. at 32 sites in 16 countries.
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 7 inclusion and 6 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: under way, not looking for participants, as of the sponsor's last update on 28 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 32 sites in Brazil, China, Turkey (Türkiye), United States, Australia and 11 more countries. 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Radiographic Global Impression of Change (RGI-C) Score at the end of the Randomized Evaluation Period (Day 169) (time frame: Day 169). 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 28 May 2026.