A Study to Evaluate Safety, Tolerability and Efficacy of AP306 At Fixed Doses in Patients with Hyperphosphatemia

The goal of this clinical trial is to learn if AP306 could work in the patients receiving maintenance hemodialysis with elevated blood phosphate. The main questions it aims to answer are:

* Does AP306 lower blood phosphate levels when the participants take a fixed dose of AP306?
* What medical problems do the participants have when taking AP306?

The researchers will compare AP306 to a placebo (a look-alike substance that contains no drug) to see if AP306 works to treat hyperphosphatemia.

The participants will:

* Stop all using blood phosphate-lowering drugs, and
* Take AP306 or a placebo three times a day for 12 weeks.

If the participant has a blood phosphate level above a certain level, they will receive additional treatment to lower the blood phosphate level.


Eligibility Criteria:
Important Inclusion Criteria:

1. Who signes a written informed consent form (ICF) and is willing to comply with all study requirements in the study
2. Who is receiving a stable hemodialysis regimen, which is defined as a frequency of three times per week for at least 12 weeks before the ICF sign off, and doesn't plan to change in the study
3. Who has a dialysis adequacy, assessed by single pooled Kt/V (SpKt/V, estimated with blood urea) ≥1.20, at screening
4. If the participant is receiving any of the following therapies, their doses are stable for at least 4 weeks before the ICF sign off visit: phosphate-lowering products other than phosphate binders, active vitamin D and analogs or nutritional vitamin D, calcimimetics, calcitonin, and P-glycoprotein inhibitors or inducers
5. Who has a blood phosphate level within the study-required range

Important Exclusion Criteria:

1. Pregnant or breastfeeding
2. Scheduled for a living donor kidney transplant in the next 6 months, planned change to peritoneal dialysis or home hemodialysis in the study; planned relocation to another dialysis center in the study
3. Any history of a non-pharmacological parathyroid intervention within 6 months prior to the ICF sign off, or planned parathyroid intervention in the study
4. Uncontrolled blood calcium abnormality
5. Uncontrolled blood intact parathyroid hormone abnormality
6. Hemoglobin \<9 mg/dL (90 g/L)
7. Acute hepatitis or significant chronic liver disease
8. Any clinically significant GI disorders within 4 weeks prior to the ICF sign off; or any history of gastrectomy; or any GI tract surgery, excluding appendectomy and polypectomy, within 12 weeks prior to the ICF sign off
9. Uncontrolled hypertension
10. Hospitalization for cardiac or cardiocerebrovascular disease within 24 weeks prior to the ICF sign off
11. Significant abnormalities of QT interval and heart rhythm on an electrocardiograph (ECG) test
12. Any active infection or infestation or any treatment with antibiotics within 2 weeks prior to the ICF sign off
13. History or presence of malignancy within 3 years prior to the ICF sign off, except basal cell skin cancer, in-situ carcinoma of the cervix, and in-situ prostate cancer
14. Concomitant use of moderate or strong cytochrome P450 (CYP) 3A inhibitors or inducers within 2 weeks or 5 half-lives, whichever is longer, prior to the ICF sign off (topical use is allowed)
15. Treatment with any investigational medication or medical device within 30 days prior to the ICF sign off