A Study to Evaluate the Effect of ASP7991 in Secondary Hyperparathyroidism Patients Undergoing Hemodialysis

To examine efficacy and safety after 12-week administration of ASP7991 in secondary hyperparathyroidism patients undergoing hemodialysis

This study is a multicenter, double-blind, randomized, Cinacalcet hydrochloride-controlled, parallel-group, dose-ascending study. Subjects judged to be eligible will be registered and randomized into either ASP7991 group (receiving ASP7991 and cinacalcet-placebo) or Cinacalcet group (receiving cinacalcet and ASP7991-placebo), and will receive 12-week (84 days) administration of study drug from first dialysis day in a week (treatment period), in a double-blind manner. The dose of the study drugs will be increased every 3 weeks in dose-ascending manner.

Follow-up assessment will be performed before starting first dialysis in a week, 1 week (7 days) after the completion of the treatment period.

Eligibility Criteria:
Inclusion Criteria:

* Patients who are on stable chronic maintenance dialysis who are receiving hemodialysis therapy 3 times/week since before 12-week (84 days) administration and are also scheduled to undergo the regimen of 3 times/week hemodialysis during the study period
* Patients with secondary hyperparathyroidism
* Patients whose serum iPTH concentration is \>240 pg/mL and corrected serum Ca is ≥ 9.0 mg/dL
* Patients who have had no changes in the following items ≥4-week (28 days).

  * Dosage and regimen, including new administration, of active vitamin D, calcitonin preparation, phosphate binder, and medication with phosphate absorption (including foods)
  * Ca concentration of the dialysate, membrane area of the dialyzer, and dialysis time of each week

Exclusion Criteria:

* Patients who underwent parathyroid intervention, such as parathyroidectomy (PTx) or percutaneous ethanol injection therapy (PEIT), within 24 weeks (168 days) prior to the administration
* Patients who have primary hyperparathyroidism
* Patients who received bisphosphonate, estrogen preparation, parathyroid hormone within 4 weeks (28 days)
* Patients with uncontrolled hypertension (systolic blood pressure ≥ 180 mmHg and diastolic blood pressure ≥ 120 mmHg are observed at \>2/3 of all confirmable measurements
* Patients who are complicated by severe heart disorder \[congestive cardiac failure (NYHA classification III or higher), or wide range of old myocardial infarction\], or having a history of hospitalization for cerebro-vascular disease or heart disorder within 12 weeks (84 days) before administration of the study drug
* Patients with hepatic function abnormal (ALT or AST is \>2× ULN, or total bilirubin (T-bil) is \> 1.5 × ULN.)
* Patients with a history of malignant tumor or the patient's condition is complicated by malignant tumor. (However, enrollment is acceptable if the tumor has not relapsed for 5 years or longer.)
* Patients with a history of serious drug allergy including anaphylactic shock
* Patients with a history of drug allergy to Cinacalcet hydrochloride
* Female patients who are potentially child-bearing or lactating, or patients who do not comply with the instructed contraceptive measures
* Patients who were or are currently involved in trials for other investigational drugs or medical devices, or clinical trial for post-marketing study drugs within 12 weeks (84 days) before the study
* Patients who have received ASP7991 in the past
* Patients who were judged ineligible to participate in the study by the

investigator / subinvestigator