Dose Escalation Study to Evaluate the Safety and Tolerability of Multiple Infusions of BPS804 in Adults With Hypophosphatasia (HPP)

Inclusion Criteria: * Male and female patients 18 to 60 years of age in good health (other than pre-established clinical diagnosis of HPP) as determined by past medical history, physical examination, vital signs, electrocardiogram, and laboratory tests at screening. * Previously established clinical diagnosis of HPP with confirmed ALPL mutation by genetic test and as manifested by: * Serum alkaline phosphatase levels below the age-adjusted normal range and * Radiologic evidence of osteopenia or osteomalacia or * History of plasma PLP at least twice the upper limit of normal range or * History of rickets, or history of premature loss of deciduous teeth, or bone deformity consistent with osteomalacia or past rickets, or past non-traumatic fracture, pseudofracture, or non-healing fracture. * 25-(OH) vitamin D3 serum level of ≥20 ng/mL. * Normocalcemia with serum calcium ≥8.5 mg/dL and ≤10.2 mg/dL and normal phosphate levels (2.4 - 4.1 mg/dL) (or according to local laboratory ranges). Exclusion Criteria: * A history of clinically significant ECG abnormalities. * History of malignancy of any organ system (other than localized basal cell carcinoma of the skin and for skeletal malignancies see below), within the past 5 years, regardless of whether there is evidence of local recurrence or metastases. * History of skeletal malignancies or bone metastases at any time. * History of external beam radiation to the skeleton. * Open epiphyses as judged by the Investigator based on previo…