Evaluation of RLY5016 Titration in Heart Failure Patients With Chronic Kidney Disease

Inclusion Criteria:

1. Chronic heart failure clinically indicated to receive spironolactone therapy
2. Age 18 years or older
3. Local lab serum potassium values of 4.3 - 5.1 mEq/L at screening and baseline
4. Chronic kidney disease (estimated GFR < 60 mL/min/1.73m2 at screening based on central lab creatinine measurement)
5. On at least one of the following heart failure therapies: ACEI, ARB, or BB
6. Females of child-bearing potential must be non-lactating, must have a negative serum pregnancy test at screening, and must have used a highly effective form of contraception for at least 3 months before study drug administration, during the study, and for one month after study completion
7. Male patients and/or their female partners of child-bearing potential must use a highly effective form of contraception during the study and for 3 months after study completion
8. Provide their written informed consent prior to participation in the study

Exclusion Criteria:

1. History of bowel obstruction, swallowing disorders, severe gastrointestinal disorders or major gastrointestinal surgery
2. Uncorrected primary severe valvular disease, known obstructive or restrictive cardiomyopathy, uncontrolled or hemodynamically unstable arrhythmia
3. Coronary-artery bypass graft, percutaneous intervention (e.g., cardiac, cerebrovascular, aortic), or major surgery including thoracic and cardiac, within 3 months prior to baseline or anticipated need during study participation
4. Heart transplant recipient, or anticipated need for transplant during study participation
5. Any of the following events having occurred within 2 months prior to baseline: unstable angina as judged by the Investigator, unresolved acute coronary syndrome, transient ischemic attack or stroke
6. Current dialysis patient, or anticipated need for dialysis during study participation
7. Prior kidney transplant, or anticipated need for transplant during study participation
8. Metastatic, late-stage or end-stage cancer with < 12 months life expectancy or at risk for tumor lysis syndrome
9. History of alcoholism or drug/chemical abuse within 1 year
10. Sustained systolic blood pressure > 180 or < 90 mmHg
11. Liver enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST)] > 3 times upper limit of normal
12. Loop and thiazide diuretics that have not been stable for at least 21 days prior to baseline or not anticipated to remain stable during study participation
13. Use of any intravenous cardiac medications within 21 days prior to baseline, or their anticipated need during study participation
14. Current use of polymer-based drugs (e.g., sevelamer, sodium polystyrene sulfonate, colesevelam, colestipol), phosphate binders (e.g., lanthanum carbonate), or other potassium binders, or their anticipated need during study participation
15. Use of potassium sparing medication including aldosterone antagonists or potassium supplements in the last 21 days prior to baseline
16. Use of any investigational medication within 30 days or 5 half-lives, whichever is longer, prior to baseline
17. Patients who have taken investigational product in this study, or a previous RLY5016 study
18. Inability to consume the study medication, or, in the opinion of the Investigator, inability to comply with the protocol
19. In the opinion of the Investigator, any medical condition, uncontrolled systemic disease, serious intercurrent illness, or extenuating circumstance occurring or persisting, within 30 days prior to baseline, that would significantly decrease study compliance or jeopardize the safety of the patient or affect the validity of the trial results