The goal of this clinical trial is to learn about the following questions in the patients receiving maintenance hemodialysis with elevated blood phosphorus:

• How much effect AP-306 has assessed by blood phosphorus lowering;
• How safe and tolerable AP-306 is.

Participants will receive either following treatments:

• AP-306, and
• Sevelamer carbonate.

Important Inclusion Criteria:

1. On a stable hemodialysis regimen at a frequency of three times per week for at least 12 weeks prior to the screening visit
2. Dialysis sufficiency SpKt/V ≥ 1.2 at the screening visit or any documented result within 12 weeks prior to the screening visit
3. Serum phosphorus within the trial-required range

Important Exclusion Criteria:

1. Pregnant or breastfeeding
2. Any history of kidney transplant
3. Any history of a parathyroid intervention
4. Any clinically significant GI disorders within 4 weeks prior to the screening visit
5. Hospitalization for cardiac or cerebrovascular disease within 24 weeks prior to the screening visit
6. Hospitalization for cardiac or cerebrovascular disease within 24 weeks prior to the screening visit
7. Documented history of hypersensitivity or allergic reactions to any of the excipients used by AP-306, or history of hypersensitivity or allergic reactions or intolerant to sevelamer carbonate