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ALXN1850

Phase 3

Hypophosphatasia | Small molecule | Rare Disease |AstraZeneca PLC|Last Updated: Jun 22, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials4
Total Enrollment212

FDA Designations

No designations recorded

Clinical trial landscape

ALXN1850 · 4 trials · 1 indication

Phase 3 3Phase 1 1
NCT06079359Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPPHypophosphatasia
ACTIVE NOT_RECRUITING30 Analytics
NCT06079372Phase 3 Study of ALXN1850 in Pediatric Participants With HPP Previously Treated With Asfotase AlfaHypophosphatasia
ACTIVE NOT_RECRUITING43 Analytics
NCT06079281Phase 3 Study of ALXN1850 Versus Placebo in Adolescent and Adult Participants With HPP Who Have Not Previously Been Treated With Asfotase AlfaHypophosphatasia
ACTIVE NOT_RECRUITING124 Analytics
PHASE3ACTIVE NOT_RECRUITING
Phase 3 Study of ALXN1850 in Treatment-Naïve Pediatric Participants With HPP
HypophosphatasiaUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Phase 3 Study of ALXN1850 in Pediatric Participants With HPP Previously Treated With Asfotase Alfa
HypophosphatasiaUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Phase 3 Study of ALXN1850 Versus Placebo in Adolescent and Adult Participants With HPP Who Have Not Previously Been Treated With Asfotase Alfa
HypophosphatasiaUnlock trial analytics

Study Endpoints

Primary Endpoints

Radiographic Global Impression of Change (RGI-C) Score at the end of the Randomized Evaluation Period (Day 169)
Day 169
Number of Participants with Treatment-emergent Adverse Events (TEAEs)
Baseline Through Day 169
Change from Baseline in 6-Minute Walk Test (6MWT) at the end of the Randomized Evaluation Period (Day 169)
Baseline, Day 169
Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Treatment Emergent Serious Adverse Events (TESAEs)
Day 1 up to Day 85

TEAEs were defined as any adverse events (AEs) that began or worsened on or after the first dose of treatment until the final follow-up visit. An SAE was an AE that met at least 1 of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization for the AE, persistent or significant disability/incapacity or substantial disruption of the ability to conduct normal life functions, congenital anomaly/birth defect (in the child of a participant who was exposed to the study drug), important medical event or reaction. TESAEs were defined as any serious AEs that began or worsened on or after the first dose of treatment until the final follow-up visit. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Secondary Endpoints

Change from Baseline in Rickets Severity Score (RSS) at the end of the Randomized Evaluation Period (Day 169)
Baseline, Day 169
Change from Baseline in 6-Minute Walk Test (6MWT) at the end of the Randomized Evaluation Period (Day 169)
Baseline, Day 169
Change from Baseline in Percent Predicted 6MWT at the end of the Randomized Evaluation Period (Day 169)
Baseline, Day 169
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
ALXN1850EXPERIMENTALStarting 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.
PlaceboPLACEBO_COMPARATORStarting 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.
asfotase alfaEXPERIMENTALStarting at Day 1 of the Randomized Evaluation Period, participants will receive asfotase alfa for a total of 24 weeks. Participants will receive 6 mg/kg/week of asfotase alfa via SC injection as either 2 mg/kg 3 times per week or 1 mg/kg 6 times per week. Part A of the OLE Period participants will have frequent visits over the first 24 weeks; Part B will have visits every 9 months for up to approximately 108 weeks.
Placebo GroupPLACEBO_COMPARATORDuring the Randomized Evaluation Period, the placebo group will receive placebo on Day 1, followed by once every 2 weeks (q2w) via SC injection for 24 weeks. Participants will enter the OLE Period and receive bodyweight dependent doses of either 20mg, 35mg, or 50mg of ALXN1850 and continue q2w dosing with ALXN1850 for up to 132 weeks.
ALXN1850 GroupEXPERIMENTALStarting 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 q2w via SC injection, for 24 weeks. Participants will enter the OLE Period and continue q2w dosing with ALXN1850 for up to 132 weeks.

Interventions

NameTypeDescription
ALXN1850DRUGParticipants will receive a ALXN1850 via subcutaneous (SC) injection.
PlaceboDRUGParticipants will receive placebo via SC injection.
asfotase alfaDRUGAsfotase alfa will be administered via SC injection.
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Eligibility Criteria

Age Range2 Years to 11 Years
SexALL
Healthy VolunteersNo
Study Sites32

Inclusion Criteria: * Diagnosis of HPP documented in the medical records, and the following criteria fulfilled without other probable cause than HPP: 1. Presence of HPP-related rickets on skeletal X-rays during the Screening Period, with a minimum Rickets Severity Score (RSS) of 1.0 AND 2. Ser...

Countries:United StatesAustraliaBelgiumBrazilCanadaChinaFinlandIsraelMexicoPolandRomaniaSpainSwedenTaiwanTurkey (Türkiye)United KingdomArgentinaJapanFranceGermanyItalySouth Korea
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Recent Changes (Last 90 Days)

LOWJun 22, 2026NCT06079281lastUpdatePostDate: changed
LOWJun 22, 2026NCT06079281lastUpdatePostDate: changed

Frequently asked questions about ALXN1850

What is ALXN1850 used for?

ALXN1850 is an investigational small molecule being developed for the treatment of hypophosphatasia (HPP), a rare inherited metabolic bone disease. It is currently in Phase 3 clinical trials for this condition.

Who makes ALXN1850?

ALXN1850 is being developed by AstraZeneca PLC (ticker: AZN). The company is conducting Phase 3 clinical trials to evaluate the drug as a treatment for hypophosphatasia.

What phase is ALXN1850 in?

ALXN1850 is in Phase 3 clinical development. It is an investigational drug and has not been approved by regulatory authorities. There are three active Phase 3 trials and one completed Phase 1 trial.

What clinical trials is ALXN1850 in?

ALXN1850 has four clinical trials. The completed Phase 1 trial is NCT04980248. Active Phase 3 trials include NCT06079281 in adolescents and adults not previously treated with asfotase alfa, NCT06079359 in treatment-naive pediatric patients, and NCT06079372 in pediatric patients previously treated with asfotase alfa.

Is ALXN1850 the same as asfotase alfa?

No, ALXN1850 is not the same as asfotase alfa. Asfotase alfa is an enzyme replacement therapy used to treat hypophosphatasia, while ALXN1850 is a separate investigational small molecule. Several ALXN1850 trials specifically enroll patients who have not been treated with asfotase alfa or who have previously received it.