R&D portfolio review and in light of the global impact of the COVID-19 pandemic

The study will evaluate safety, tolerability, efficacy, pharmacokinetics, and pharmacodynamics of 2 different doses (approved dose and lower dose) of asfotase alfa in adult participants with pediatric-onset hypophosphatasia (HPP).

Inclusion Criteria:

• Male or female aged ≥ 18 years at the time of signing the informed consent form
• Clinical diagnosis of pediatric-onset HPP based on signs and symptoms consistent with HPP
• Past medical history that includes at least one nonvertebral fracture (or pseudofracture) incurred without evidence of significant trauma.
• The presence of a current fracture is not necessary, but for participants with current unhealed fracture(s) or pseudofracture(s) of the lower extremity(ies) (that is, femoral, tibial, fibular, metatarsal) documentation must be provided of the presence of these fractures for at least 3 months prior to screening (with or without surgical intervention)

Exclusion Criteria:

• Medical condition, serious concurrent or recurrent illness and/or injury, or other extenuating circumstance that, in the opinion of the Investigator, may significantly interfere with study compliance or the assessment of study endpoints, including all protocol required evaluations and follow up activities, or may put the patient at risk
• Primary or secondary hyperparathyroidism or hypoparathyroidism
• History of hypersensitivity to any ingredient contained in asfotase alfa
• Oral bisphosphonate use within 6 to 12 months (depending on the half-life of the drug as assessed by the investigator) and intravenous (IV) bisphosphonate use within 12 months prior to screening
• Denosumab use within 18 months prior to screening
• Asfotase alfa use within 6 months prior to screening
• Teriparatide/parathyroid hormone analog use within 2 months prior to screening
• Treatment with strontium or sclerostin inhibitors within 6 months prior to the first dose of study drug
• Vitamin B6 use for at least 2 weeks prior to screening
• Serum 25-hydroxy (25-OH) vitamin D below 20 nanogram (ng)/milliliter (mL), with repletion and recheck allowed at screening (results from local laboratory may be used if within 4 weeks of screening)
• Female patients who are pregnant, planning to become pregnant, or breastfeeding