Non-interventional Substudy of ALX-HPP-502 to Assess Natural History of Patients With Juvenile-onset HPP Who Served as Historical Controls in ENB-006-09

Study Overview
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Brief Summary
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The purpose of this study is to characterize the natural history of HPP in patients with Juvenile-onset HPP who served as historical controls in ENB-006-09.

Detailed Description
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Hypophosphatasia (HPP) is a life-threatening, genetic, and ultra-rare metabolic disease characterized by defective bone mineralization and impaired phosphate and calcium regulation that can lead to progressive damage to multiple vital organs, including destruction and deformity of bones, profound muscle weakness, seizures, impaired renal function, and respiratory failure. There are no approved disease-modifying treatments for patients with this disease. There is also limited data available on the natural course of this disease over time, particularly in patients with the juvenile-onset form.

Official Title
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A Single-Center, Non-interventional Substudy of ALX-HPP-502 to Assess Functional Natural History Data of Patients With Juvenile Historical Controls in ENB-006-09

Conditions
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Hypophosphatasia, Bone Disease

Intervention / Treatment
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* Biological: Retrospective Case Only


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Documented informed consent/assent prior to video collection and data abstraction. Documented informed consent/assent in Study ALX-HPP-502. Patients with juvenile-onset HPP and was selected as a historical-control for Study ENB-006-09. Patients with at least 2 videos of basic mobility that were recorded at 2 different clinic visits when the patient was ≥5 to ≤15 ye Exclusion Criteria: There are no exclusion criteria for this study

Ages Eligible for Study
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Minimum Age: 5 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Retrospective Case Only<br> | Biological: Retrospective Case Only<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Modified Performance-Oriented Mobility Assessment-Gait Subtest (MPOMA-G) - Change From Baseline to Last Overall | The MPOMA-G is a 5-component assessment that is used to evaluate gait performance. The first component has 4 sub-components. For 2 components and 2 sub-components, scores of 0 or 1 are assigned while scores of 0, 1 or 2 are assigned to the rest of the 2 components and 2 sub-components based on type of ambulation pattern observed. The maximum total score of 12 points = no impairment and 0 points = worst impairment. | The earliest available MPOMA-G score that was assessed within the period of patients' aged 5 to 15 years, inclusive. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Performance-Oriented Mobility Assessment-Gait Subtest (POMA-G) - Change From Baseline to Last Overall | The POMA-G is a 7-component assessment that is used to evaluate gait performance. The second component has 4 sub-components. Scores of 0, 1 or 2 are assigned to 2 components while scores of 0 or 1 are assigned to the rest of the 4 components and 4 sub-components based on type of ambulation pattern observed. The maximum total score of 12 points = no impairment and 0 points = worst impairment. | The earliest available MPOMA-G score that was assessed within the period of patients' aged 5 to 15 years, inclusive. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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HPP, Soft Bones, low Alkaline Phosphatase, genetic metabolic disorder, alkaline phosphatase, tissue non-specific alkaline phosphatase, rickets, osteomalacia