Pharmacodynamic & Safety of Patiromer in Children & Adolescents (2-<18 Yrs) With Chronic Kidney Disease and Hyperkalemia

Up to 54 subjects, 2 - < 18 years of age with CKD (estimated glomerular filtration rate
[eGFR] < 60 mL/min/1.73 m2 ) and hyperkalemia (two potassium measurements of 5.1 to < 6.5
mEq/L performed on separate days) will be enrolled in this open-label, multiple-dose, Phase 2
study. The study will include two treatment phases: Pharmacodynamic (PD; drug effect on
potassium) / Dose Finding Phase consisting of the initial 14-day dose finding period followed
by an up to 5.5-month Long-Term Treatment Phase for a total study participation duration for
individual subjects of up to 6.5 months (includes a 2 week follow up period).

Inclusion Criteria:

- Written assent (when applicable) and written informed consent by a legally authorized
representative provided prior to participation in the study

- Age 2 - <18 years old

- CKD defined by eGFR <60 mL/min/1.73m2 including renal transplant, peritoneal dialysis

- Two potassium measurements of 5.1 to < 6.5 mEq/L performed on separate days

- In the opinion of the study doctor, is expected to require treatment for hyperkalemia
for at least 6 months

- If taking any renin-angiotensin-aldosterone system inhibitors (RAASi) beta blockers or
diuretic medications, must be on a stable dose for at least 28 days prior to Screening

- Negative pregnancy test in females of child-bearing potential

Exclusion Criteria:

- False elevation in blood potassium (pseudohyperkalemia) due to hemolysis (breaking of
blood cells) or abnormally high counts of blood cells at Screening

- Evidence of potassium-related electrocardiogram (ECG) changes at Screening

- Any of the following kidney conditions: hemodialysis, renal artery stenosis, and acute
kidney injury or a history of acute renal insufficiency in the past 3 months

- Severe disorder of stomach or intestines including surgery

- Increased liver enzymes (ALT, AST > 3 times upper limit of normal) at Screening

- Active cancer, currently on cancer treatment or history of cancer in the past 2 years
(except for non-melanoma skin cancer)

- Have had a heart or liver transplant, or anticipated need for transplant during the
study treatment period including a scheduled kidney transplant. (Note: patients
currently on a kidney transplant wait list are not excluded unless there is an
identified donor).

- Alcohol abuse or substance use disorder within 1 year of Screening

- Subjects currently being treated with or having taken any one of the following
medications (includes resins) in the 7 days prior to Screening: sodium or calcium
polystyrene sulfonate, drospirenone

- Use of certain medications that can affect blood potassium levels if doses have not
been stable for at least 14 days prior to Screening or if doses are anticipated to
change during the 14-day PD / Dose Finding Phase

- Use of investigational product within 30 days of screening or within 5 half-lives,
whichever is longer

- Known hypersensitivity to patiromer or its components

- In the opinion of the Investigator, any medical condition, uncontrolled systemic
disease, or serious intercurrent illness that would significantly decrease study
compliance or jeopardize the safety of the subject or potentially affect the quality
of the data