A Clinical Study of TS-172 in Hyperphosphatemia Patients on Peritoneal Dialysis

• 'TS-172 20~60 mg/day (Drug): oral administration of TS-172 20\~60 mg/day

Primary outcomes

• Achievement rate of the target serum phosphorus level [Week 8]

Secondary outcomes

• Change from baseline in serum concentration of phosphorus [Up to Week 16]
• Concentration of corrected serum calcium [Up to Week 16]
• Serum Ca × P product [Up to Week 16]

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Hyperphosphatemia patients (outpatients) with chronic kidney disease receiving peritoneal dialysis (CAPD or APD) at least 12 weeks prior to Visit 1 (Week -4)
2. Patients aged >= 18 years at the time of obtaining informed consent
3. Patients who are receiving at least one phosphate binder and whose dosing regimen for all phosphate-lowering agents (phosphate binder and tenapanor hydrochloride) has been unchanged during the last 4 weeks prior to Visit 1 (Week -4).
4. Patients with serum phosphorus concentration of >= 3.5 mg/dL and =< 7.0 mg/dL at Visit 1 (Week -4)
5. Patients whose serum phosphorus concentration at Visit 2 (Week -2) or Visit 3 (Week -1) or Visit 4 (Week 0) has increased by at least 1.0 mg/dL compared with the value at Visit 1 (Week -4) and is >= 5.5 mg/dL and < 10.0 mg/dL.

Exclusion Criteria:

1. Patients with confirmed serum intact PTH concentration >500 pg/mL from Visit 1 (Week -4) to Visit 4 (Week 0)
2. Patients with serum phosphorus concentration >= 10.0 mg/dL from Visit 2 (Week -2) or Visit 3 (Week -1)
3. Patients who have undergone previous parathyroid intervention (PTx, PEIT, etc.)

• Taisho Director, Study director, Taisho Pharmaceutical Co., Ltd.