Study to Evaluate the Safety and Tolerability of Ferric Citrate in Children With Hyperphosphatemia Related to Chronic Kidney Disease

A 36-week, Single-Arm, Open-label Study to Evaluate the Safety and Tolerability of Ferric Citrate in Children With Hyperphosphatemia Related to Chronic Kidney Disease

This study will be conducted to assess the safety and tolerability of ferric citrate in pediatric participants with hyperphosphatemia related to chronic kidney disease (CKD).

Study Overview

• Status: Suspended
• Conditions: Hyperphosphatemia Related to Chronic Kidney Disease
• Intervention / Treatment: Drug: ferric citrate

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Phase 3

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35233
      • University of Alabama at Birmingham (UAB) - Children's of Alabama
  • Arizona
    • Phoenix, Arizona, United States, 85016
      • Phoenix Childrens Hospital
  • California
    • San Francisco, California, United States, 94158
      • University of California, San Francisco (UCSF) - Department of Nephrology
    • Stanford, California, United States, 94305
      • Stanford University Medical Center
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Children's Hospital Colorado
  • Florida
    • Tampa, Florida, United States, 33606
      • University Of South Florida
  • Maryland
    • Baltimore, Maryland, United States, 21287
      • Johns Hopkins Hospital
  • Michigan
    • Grand Rapids, Michigan, United States, 49503
      • Helen DeVos Children's Hospital at Spectrum Health
  • Minnesota
    • Minneapolis, Minnesota, United States, 55455
      • University of Minnesota
  • Missouri
    • Kansas City, Missouri, United States, 64108
      • Children's Mercy Hospital - Kansas City
  • New Mexico
    • Albuquerque, New Mexico, United States, 87110
      • University of New Mexico
  • Ohio
    • Cincinnati, Ohio, United States, 45229
      • Cincinnati Children's Hospital Medical Center
  • Utah
    • Salt Lake City, Utah, United States, 84113
      • University of Utah
  • Washington
    • Seattle, Washington, United States, 98105
      • Seattle Children's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 12 years to 17 years (Child)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 6 years to <17 years at Screening.
• Weight ≥ 20 kilograms (kg) (dry weight for dialysis participants) at Screening.
• Chronic kidney disease (CKD) requiring chronic dialysis (i.e., hemodialysis or peritoneal dialysis), or CKD not on dialysis with an estimated glomerular filtration rate (eGFR) <30 milliliters per minute (mL/min)/1.73 meters squared (m^2) at Screening.
• Documented history of CKD-related hyperphosphatemia for at least 3 months prior to the screening visit.

• If participant is or is not on phosphate binder(s) at Visit 1, serum phosphorus must be:

  • 6 to <13 years: >5.8 milligrams per deciliter (mg/dL).
  • 13 to <17 years: >4.5 mg/dL.
• If participant is on phosphate binder(s) at Visit 1, and serum phosphorus is not greater than the above stated age-limit criteria, approximately 1 to 4-weeks of washout period is required and at Visit 1a or Visit 1b, serum phosphorus must be greater than the age above stated age-limit criteria.
• Transferrin saturation (TSAT) <50%.
• Serum ferritin of <650 nanograms per milliliter (ng/mL).
• Parent/legal guardian must be willing and able to give written informed consent, and child (participant) willing and able to give age-appropriate assent according to local regulatory requirements.
• Female participants of childbearing potential, defined as post menarche and not surgically sterile, must have a negative serum pregnancy test.

• Dialysis adequacy stable on current mode of dialysis prior to screening and agree to maintain dialysis prescription for the duration of the pharmacodynamic assessment period unless changes are needed for safety. A minimum dialysis adequacy (dialysis clearance of urea-dialysis time/volume of distribution of urea [Kt/V]), defined by the following:

  1. Hemodialysis adequacy: single-pool Kt/V ≥1.2 for at least 1 hemodialysis session within 2 months.
  2. Peritoneal dialysis: At least 1Kt/V reading ≥1.8 within 4 months.

Exclusion Criteria:

• Active significant GI disorder, including overt GI bleeding or active inflammatory bowel disease.
• Liver transaminases (aspartate aminotransferase [AST] or alanine aminotransferase [ALT]) >3× the upper limit of normal at Screening.
• Unable to swallow pills, if participant requires tube feeding, ferric citrate must be taken orally and not administered via feeding tube.
• Non-renal cause of hyperphosphatemia.
• Active drug or alcohol dependence or abuse (excluding tobacco use or medicinal marijuana) within the 12 months prior to Screening or evidence of such abuse (in the opinion of the Investigator).
• Malignancy, except for participants who have been disease-free for at least 2 years after curative therapy.
• Participants with a functioning organ transplant.
• A known allergy or intolerance to ferric citrate or any of its constituents.

• Female participants who do not agree to remain abstinent or assent to use a combination of 2 of the following highly effective birth control methods for at least 28 days before the first dose, during the study (including during dose interruptions), and for at least 30 days after the last dose:

  • Barrier method of contraception: condoms (female or male) with or without a spermicidal agent, diaphragm, or cervical cap with spermicide.
  • Intrauterine device (IUD).
  • Hormone-based contraceptives which are associated with inhibition of ovulation.
• Females who are pregnant or breast-feeding other children. Participants who are being breastfed are eligible to participate in this study.
• Any other medical condition that, in the opinion of the Investigator, renders the participant unable to or unlikely to complete the trial or that would interfere with optimal participation in the trial or produce significant risk to the participant.
• The participant, in the opinion of the Investigator, is unable to adhere to the requirements of the study.
• Receipt of any investigational drug within 4 weeks before Screening.
• History of hemochromatosis or iron overload syndrome (e.g, hereditary sideroblastic anemia, thalassemia).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ferric citrate; Participants aged 6 to < 17 years will receive ferric citrate for 36 weeks at a starting dose based on body weight categories.	Drug: ferric citrate; oral tablets; Other Names: KRX-0502

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Number of participants with serious and non-serious treatment-emergent adverse events (TEAEs) including gastrointestinal (GI) AEs of special interest	up to Week 40
Number of participants with clinically significant laboratory abnormalities or changes in laboratory results	up to Week 40
Number of participants with TEAEs leading to the discontinuation of ferric citrate	up to Week 40

Secondary Outcome Measures

Outcome Measure	Time Frame
Change from baseline in serum phosphorus to Week 12/early termination (ET)	Baseline; up to Week 12

Collaborators and Investigators

• Sponsor: Keryx Biopharmaceuticals
• Investigators: Study Director: Chief Medical Officer, Akebia Therapeutics

Study record dates

Study Major Dates

• Study Start (Actual): June 16, 2022
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): October 1, 2027

Study Registration Dates

• First Submitted: August 19, 2020
• First Submitted That Met QC Criteria: August 19, 2020
• First Posted (Actual): August 24, 2020

Study Record Updates

• Last Update Posted (Actual): May 14, 2026
• Last Update Submitted That Met QC Criteria: May 12, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: pediatric; chronic kidney disease; dialysis; CKD; hyperphosphatemia; ferric citrate
• Additional Relevant MeSH Terms: Urogenital Diseases; Pathologic Processes; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Chronic Disease; Disease Attributes; Metabolic Diseases; Renal Insufficiency; Phosphorus Metabolism Disorders; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Renal Insufficiency, Chronic; Hyperphosphatemia; ferric citrate
• Other Study ID Numbers: KRX-0502-308

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No