The purpose is to evaluate the tolerability, safety and efficacy of VS-505 when given with meal for 8 weeks to hemodialysis patients with hyperphosphatemia

This study consists of 4 period; 1) screening period: up to 30 days, 2) first washout period: 2 weeks (remove existing phosphate binder effect), 3) treatment period: 8 weeks, and 4) second washout period: 2 weeks (remove VS-505 effect). VS-505 is orally administered with meal for 8 weeks. The starting dose of VS-505 is 1.50 g/day and the dose will be elevated step wise from 1.50 g to 2.25 g, 4.50 g and 6.75 g per day based on the safety assessment and plasma Pi level every 2 weeks during the treatment period.

Inclusion Criteria:

• Written informed consent given

• Able to comply with the study procedures and medications

• On a stable hemodialysis (HD) regimen (3 times per week) including hemodialysis and hemodiafiltration for ≥12 weeks at screening and during the study period

• No change in prescribed dose or frequency of any of the following medications within 4 weeks prior to screening

  1. Injectable iron agents
  2. Oral or injectable active vitamin D3
  3. Oral nutritional vitamin D
  4. Calcimimetics
  5. Calcium supplements
  6. Anti-osteoporotic medication including bisphosphonates
  7. Calcitonins

• Must be willing to avoid intentional changes in diet throughout the study

• Women of child-bearing potential or non-sterile male subjects and those who are sexually active with a non-sterile female partner must agree to use highly effective contraception

• Plasma Pi level >1.94 mmol/L (6.0 mg/dL) to <3.23 mmol/L (10.0 mg/dL) after 2 weeks washout will qualify patients to enter the treatment period

Exclusion Criteria:

• Blood purification therapy other than HD (hemodialysis and hemodiafiltration)
• The plasma Pi level is >2.26 mmol/L (7.0 mg/dL) within the latest three tests prior to screening.
• Variation of the plasma Pi is over 0.65 mmol/L (2.0 mg/dL) within the latest three tests prior to screening.
• Pre-emptive or scheduled renal transplant
• History of hemochromatosis or ferritin ≥1000 mcg/L
• Oral iron agents including prescribed and over-the-counter drugs at screening.
• Current clinically significant gastrointestinal (GI) disorder, including GI bleeding, colitis, inflammatory bowel disease, irritable bowel syndrome, chronic constipation, new diagnosis of peptic or duodenal ulcer disease, within 4 weeks prior to screening
• History of gastrectomy or duodenectomy, or GI tract surgery within 12 weeks prior to screening
• Hypertension: Defined using pre-dialysis vital of diastolic blood pressure >110 mmHg or systolic blood pressure >180 mmHg
• Possible parathyroid intervention including surgical parathyroidectomy and percutaneous ethanol injection therapy during the study period
• Clinical evidence of active malignancy and/or receiving systemic chemotherapy/radiotherapy with the exception of basal cell or squamous carcinoma of the skin
• Severe cardiovascular disorders such as recent myocardial infarction; unstable angina; congested heart failure (NYHA class II or above) hospitalized within 24 weeks (6 months), valve stenosis, atrial fibrillation and arrhythmia
• History of event by cerebrovascular disease or cardiovascular disease within 24 weeks (6 months) prior to screening
• Active infection or current treatment with antibiotics within 2 weeks prior to screening
• History of HIV (ELISA and Western blot) test results
• Known active liver disease with aspartate aminotransferase or alanine aminotransferase levels greater than x3 the upper limit of normal
• Hepatitis B and/or hepatitis C treated with antiviral treatment within 4 weeks prior to screening
• History of allergy of VS-505 and its related components
• Receipt of any investigational drug within 4 weeks prior to screening
• Pregnant and breast-feeding women
• Other patients who in the opinion of the investigators are ineligible for the study