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

Elevated serum phosphate is a ubiquitous complication of reduced kidney function and evidence
suggests that this metabolic disturbance is associated with cardiovascular morbidity and
mortality in subjects receiving haemodialysis Efforts to achieve normal serum phosphate with
dietary restrictions, thrice weekly dialysis and phosphate binders have failed to
substantially improve the achieved serum phosphate levels. Data from a large international
practice pattern study suggest that approximately 50% of all dialysis subjects have serum
phosphate above the recommended target value of 5.5 mg/dL The standard of care for phosphate
control remains the prescription of phosphate binders with meals. These drugs act in the
small intestine to bind phosphate and prevent its absorption into the bloodstream. The 2
general categories of phosphate binders currently commercially available include calcium
containing phosphate binders (calcium carbonate and calcium acetate) and the non calcium
containing phosphate binders (sevelamer carbonate and lanthanum carbonate While these 2
classes of phosphate binders have similar efficacy, they differ substantially in their
associated side effects.

Inclusion Criteria:

- Men or women aged 18 90 years

- Subject must have a stable dialysis prescription for at least 28 days prior to start
of Screening.

- Subject must have the most recent serum phosphate measurement, taken during the 28
days prior to the start of Screening, of ≥ 4.0 mg/dL and ≤ 8 mg/dL.

Exclusion Criteria:

- Subject's most recent historical pre-dialysis serum bicarbonate value within 14 days
prior to the start of Screening (Visit 1) is < 18 mg/dL.

- Subject has, in the opinion of the investigator, severe chronic lung disease and/or
carbon dioxide retention.