Safety, Pharmacokinetics and Pharmacodynamics of BPS804 in Osteogenesis Imperfecta

The assessment of safety will be based on primarily on the frequency of adverse events, laboratory abnormalities, and serious adverse events suspected by the investigators to be related to study treatments. The AE collection period extends from the time of first study drug administration drug until study completion. The intensity of each AE will be characterized and classified into 1 of the 3 generic categories (mild, moderate, or severe). The number and percentage of patients with adverse events will be tabulated by treatment group, body system and preferred term. The periods for adverse event tabulation will be from dose administration up to next dose administration if a further dose is given, and from dose administration to EOS for the last dose administration of a patient.

Biomarker data from serum bone formation biomarkers: procollagen type I N-terminal propeptide, procollagen type I C-terminal propeptide, osteocalcin, and bone-specific alkaline phosphatase, and from serum bone resporption mbiomarkers: C-telopeptides of type I collagen cross-links, and N-telopeptides of type I collagen cross-links will be reported as concentration results, measured using a specific assay with a working range defined by the Lower limit of quantification and Upper limit of quantification. It will be considered a sign for efficacy, if any of the above show significant (2-sided, alpha=0.05) increase versus baseline in the BPS804 group on day 43.

Bone mineral density will be assessed by dual-energy X-ray absorptiometry of the lumbar spine. Analysis will include four vertebral levels from L1 to L4. Individual vertebral levels may be excluded due to artifact. Bone mineral density Z-scores will be used as these are a comparison of a patient's BMD to that of a patient of the same age, sex, and ethnicity. The comparison of change from baseline with the matching change in the reference group will be done by 2-sample t-tests (1-sided). It will be considered a sign for efficacy, if any of the above show significant (2-sided, alpha=0.05) increase versus baseline in the BPS804 group on day 141.

Individual and overlaying individual serum concentration-time profiles of BPS804 will be constructed from the serial sampling on Day 1 (prior to administration and 3x after administration) and Days 2, 8, 15 (2x), 16, 29 (4x), 30, 36, 43, 57, 85, 113,141. In addition arithmetic and geometric mean serum concentration-time profiles of BPS804 will be constructed from the above data points.

The area under the serum concentration-time curve from time zero to the end of the dosing interval tau after the first dose will be derived using using non-compartmental methods from data collected on Day 1 (4x) and Days 2, and 8.

The maximal concentration after the first dose will be derived using using non-compartmental methods from data collected Day 1 (4x) and Days 2, and 8.

The time of maximal concentration after the first dose will be derived using using non-compartmental methods from data collected Day 1 (4x) and Days 2, and 8.

The maximal concentration after the second dose will be derived using using non-compartmental methods from data collected from days 15 (2x) and 16.

The time of maximal concentration after the second dose will be derived using using non-compartmental methods from data collected from days 15 (2x) and 16.

The area under the serum concentration-time curve from time zero to the end of the dosing interval tau after the third dose will be derived using non-compartmental methods from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141.

The area under the serum concentration-time curve from time zero to the time of the last quantifiable concentration after the third dose will be derived using non-compartmental methods from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141.

The area under the serum concentration-time curve from time zero to the end of the dosing interval tau after the third dose will be derived using non-compartmental methods from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141.

The maximal serum concentration after the third dose will be derived using using non-compartmental methods from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141.

The time of maximal concentration after the third dose will be derived using using non-compartmental methods from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141.

The terminal elimination half-life after the third dose will be derived from data collected on Days 29 (4x), 30, 36, 43, 57, 85, 113, and 141 using a compound-specific modeling approach.

The function of sclerostin is described as an endogenous negative regulator of bone formation. Total serum sclerostin will be measured from samples collected at screening and on days 1, 8, 15, 29, 36, 43, 57, 85, 113, and 141

Immunogenicity will only be assessed in patients randomized to the treatment group. Anti-BPS804 antibodies will be measured in human serum on Days 1, 29, 85, and 141 An immunogenicity positive patient at end of study will be followed up until anti-BPS804 antibody levels are back to levels measured on Day 1.