Study to Evaluate the Efficacy and Safety of PT20 in Subjects With Hyperphosphataemia and Dialysis Dependent Chronic Kidney Disease

The primary efficacy endpoint was the change in serum phosphate concentration from Baseline (Visit 7, Day 1) to Visit 11 (Day 29). All study specific blood samples were collected, processed and analysed using a central laboratory.

Descriptive statistics were to be used to summarise values and change from Baseline (Visit 7, Day 1) to Day 29 (Visit 11) in haemoglobin concentration. An analysis of covariance (ANCOVA) was to be used to analyse the changes from Baseline (Visit 7, Day 1) to Visit 11 (Day 29), which were to include the fixed, categorical effects of treatment as well as the continuous, fixed covariates of Baseline concentrations for haemoglobin. Only those subjects with available concentrations for both Baseline (Visit 7, Day 1) and Visit 11 (Day 29) were to be included in this analysis.

Descriptive statistics were to be used to summarise values and change from Baseline (Visit 7, Day 1) to Day 29 (Visit 11) in serum ferritin concentration. An analysis of covariance (ANCOVA) was to be used to analyse the changes from Baseline (Visit 7, Day 1) to Visit 11 (Day 29), which were to include the fixed, categorical effects of treatment and week (Visit), as well as the continuous, fixed covariates of Baseline concentrations for serum ferritin. Only those subjects with available concentrations for both Baseline (Visit 7, Day 1) and Visit 11 (Day 29) were to be included in this analysis.

Descriptive statistics were to be used to summarise values and change from Baseline (Visit 7, Day 1) to Day 29 (Visit 11) in transferrin saturation. An analysis of covariance (ANCOVA) was to be used to analyse the changes from Baseline (Visit 7, Day 1) to Day 29 (Visit 11), which were to include the fixed, categorical effects of treatment and week, as well as the continuous, fixed covariates of Baseline concentrations for transferrin saturation. Only those subjects with available concentrations for both Baseline (Visit 7, Day 1) and Visit 11 (Day 29) were to be included in this analysis.

Descriptive statistics were to be used to summarise values and change from Baseline (Visit 7, Day 1) to Day 29 (Visit 11) in Calcium x Phosphate Product . An analysis of covariance (ANCOVA) was to be used to analyse the changes from Baseline (Visit 7, Day 1) to Day 29 (Visit 11), which were to include the fixed, categorical effects of treatment, as well as the continuous, fixed covariates of Baseline concentrations for Calcium x Phosphate Product. Only those subjects with available concentrations for both Baseline (Visit 7, Day 1) and Visit 11 (Day 29) were to be included in this analysis. In CKD subjects (Stages 3-5), the clinical recommendation (KDOQI) is that serum calcium x phosphate product should be maintained at < 55 mg^2/dL^2 (4.4 mmol^2 /L^2).

The GSRS assesses the impact of treatment-related GI complications. It includes 15 items divided into 5 subscales (diarrhoea, indigestion, abdominal pain, constipation, and reflux), and uses a seven-grade Likert scale to assess symptoms (1 = no discomfort at all, 7 = very severe discomfort). The total score was calculated as the average score of all 15 items. If data were missing from one or more subscales, the mean of the completed items within the subscale was to be used for the subscale score, provided that more than half of the subscale items were complete. If more than half of the items within a subscale were missing, the subscale score and overall score were also to be defined as missing. The change in overall GSRS score from Baseline (Visit 7, Day 1) to Visit 11 (Day 29) was summarised by treatment and a two-sample t-test was to be used to identify differences between the placebo and PT20 dose groups. The higher the score, the more severe the gastrointestinal symptoms.