Ferric Citrate and Chronic Kidney Disease in Children (FIT4KID)

April 14, 2026 updated by: Isidro Salusky, MD, University of California, Los Angeles

Phosphate Binder Therapy and Chronic Kidney Disease in Children

We will conduct a 12-month, double-blind, randomized, placebo-controlled trial to assess the effects of therapy with ferric citrate (FC) on changes in intact FGF23 levels (iFGF23, primary endpoint) in 160 pediatric patients (80 in each of the two arms) aged 6-18 years of either sex with chronic kidney disease (CKD) stages 3-4 and age-appropriate normal serum phosphate levels. Participants will be randomized to one of the two groups: 1) FC or 2) FC placebo. Participants will be recruited from 20 core clinical sites.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

We will conduct a double-blind, randomized, placebo-controlled trial to assess the effects of therapy with ferric citrate (FC) on changes in intact FGF23 levels (iFGF23, primary endpoint) aged 6-18 years of either sex with chronic kidney disease (CKD) stages 3-4 and age-appropriate normal serum phosphate levels. Participants will be randomized to one of the two groups: 1) FC or 2) FC placebo. Participants will be recruited from 20 core clinical sites.

Schedule of Intervention: During the 12-month trial, participants will be given a daily fixed weight-based dose of FC.

Schedule for data collection/analyses to be performed:

Blood for primary outcome assessments will be collected at screening, baseline and at months 3, 6, 9, 12. Blood for safety assessments will be collected at the the months 1, 2, 3, 6, 9, 12.

The primary analyses for this 2-arm trial will compare log-transformed iFGF23 values over 12 months between the treatment and the placebo arms. The analysis will use a linear mixed-effects model, including stratification factors CKD stage and urine protein to creatinine ratio, with random participant effects accounting for repeated measurements, and a fixed treatment effect, which interacts with a time indicator (Months 3-12 vs. Baseline/Screening).

Primary objectives:

  • To assess the effects of therapy with FC on iFGF23 levels
  • To determine safety and tolerability of FC.

Secondary objectives:

• To assess the effects of FC on anemia and indices of mineral and bone metabolism.

Primary Endpoint:

• iFGF23 level

Safety and Tolerability Endpoints:

• Ability to safely tolerate FC

Secondary Endpoints:

  • Anemia
  • Indices of mineral and bone metabolism

This is a Phase 2 study with participation from 20 sites that will take 36 months to complete enrollment and a total of 48 months to complete data collection with each participant being part of the study for 12 months.

Study website: fit4kid.dgsom.ucla.edu

Study Type

Interventional

Enrollment (Estimated)

160

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Canada
    • British Columbia
      • Vancouver, British Columbia, Canada, V5Z 4H4
        • Recruiting
        • BC Children's Hospital Research Institute
        • Principal Investigator:
          • Tom Blydt-Hansen, MD
        • Contact:
    • Ontario
      • Toronto, Ontario, Canada, M5G 1E8
        • Recruiting
        • SickKids
        • Contact:
          • Yasmine Hejri-Rad
          • Phone Number: 309031 416-813-7910
        • Principal Investigator:
          • Michael Zappitelli, MD
  • United States
    • California
      • Los Angeles, California, United States, 90095
        • Recruiting
        • University of California, Los Angeles
        • Contact:
        • Principal Investigator:
          • Isidro Salusky, MD
      • Orange, California, United States, 92868
        • Recruiting
        • Children's Hospital of Orange County
        • Contact:
        • Principal Investigator:
          • Shoba Nayran, MD
      • San Francisco, California, United States, 94143
        • Recruiting
        • University of California, San Francisco
        • Contact:
        • Principal Investigator:
          • Farzana Perwad, MD
        • Sub-Investigator:
          • Anthony Portale, MD
    • Florida
      • Orlando, Florida, United States, 32806
        • Recruiting
        • Arnold Palmer Hospital for Children
        • Principal Investigator:
          • Jorge Ramirez, MD
        • Contact:
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Recruiting
        • Emory University
        • Principal Investigator:
          • Sabina Kennedy, MD
        • Contact:
    • Indiana
      • Indianapolis, Indiana, United States, 46202
        • Recruiting
        • Indiana U
        • Contact:
        • Principal Investigator:
          • khalid Myda, MD
    • Missouri
      • Kansas City, Missouri, United States, 64110
        • Recruiting
        • Children's Mercy Hospital, Kansas City
        • Contact:
        • Principal Investigator:
          • Bradley Warady, MD
      • St Louis, Missouri, United States, 63130
        • Recruiting
        • Washington U
        • Contact:
        • Principal Investigator:
          • Keith Hruska, MD
    • New York
      • New York, New York, United States, 11040
        • Recruiting
        • Cohen's Childrens
        • Contact:
        • Principal Investigator:
          • Christina Sethna, MD
      • The Bronx, New York, United States, 10467
        • Recruiting
        • Children's Hospital at Montefiore
        • Contact:
        • Principal Investigator:
          • Frederick Kaskel, MD
    • North Carolina
      • Durham, North Carolina, United States, 27708
        • Not yet recruiting
        • Duke
        • Contact:
    • Ohio
      • Cincinnati, Ohio, United States, 45229
        • Recruiting
        • Cincinnati Children's Hospital Medical Center
        • Contact:
        • Principal Investigator:
          • Mark Mitsnefes, MD
      • Columbus, Ohio, United States, 43205
    • Oregon
      • Portland, Oregon, United States, 97239
        • Not yet recruiting
        • OHSU
        • Principal Investigator:
          • Amira Al-Uzri, MD
        • Contact:
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Recruiting
        • Children's Hospital of Philadelphia
        • Contact:
        • Principal Investigator:
          • Michelle Denburg, MD
    • Texas
      • Dallas, Texas, United States, 75235
        • Recruiting
        • Children's Medical Center, Dallas
        • Contact:
        • Principal Investigator:
          • Raymond Quigley, MD
      • Houston, Texas, United States, 77030
        • Recruiting
        • Baylor College of Medicine
        • Principal Investigator:
          • Poyyapakkam R Srivanthos, MD
        • Contact:
      • Houston, Texas, United States, 77030

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

6 years to 17 years (Child, Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Ages 6 to 18 years (inclusive);
  2. Estimated Glomerular Filtration Rate (GFR) of 15-59 ml/min per 1.73 m2 by modified Chronic Kidney disease in Children (CKiD) under 25 (U25) formula;56
  3. Serum phosphate <=5.9 mg/dl;
  4. Serum ferritin <500 ng/ml and TSAT <50%;
  5. For those patients treated with growth hormone, calcitriol, nutritional vitamin D, iron, and/or erythropoiesis-stimulating agents (ESAs) such treatments must have stable dosing for at least 2 weeks prior to screening;
  6. Able to swallow tablets;
  7. Able to eat at least two meals a day;
  8. In the opinion of the investigator, willing and able to follow the study treatment regimen and comply with the site investigator's recommendations.

Exclusion Criteria:

  1. Patients currently treated with phosphate binders.
  2. History of allergy to all ingredients (including non-medical ingredients) in both products (i.e. investigational product and placebo)
  3. Current intestinal malabsorption, documented in the medical record; disease, inflammatory bowel syndrome, and/or Crohn's Disease.
  4. Anticipated initiation of dialysis or kidney transplantation within 6 months
  5. Current or planned future systemic immunosuppressive therapy
  6. Prior solid organ transplantation
  7. Receipt of bone marrow transplant within two years of screening
  8. Current pregnancy, lactation or female subjects who have reached menarche, unless using highly-effective contraception as outlined in section 7.1.1 of Protocol
  9. Patients participating in other interventional study (observational study participation permitted)
  10. Poor adherence to medical treatments in the opinion of the investigator
  11. Cystinosis
  12. Fanconi syndrome
  13. Hemochromatosis or laboratory tests indicating possible hemochromatosis or other iron overload (primary or secondary) syndrome

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Treatment Arm
During the 12-month trial, participants will be given a fixed weight-based dose of Ferric Citrate (FC). The full medication dose will be 3g/day for participants weighing <31 kg, 5g/day for those weighing >31 - <51 kg, and 6g/day for participants >51 kg. These doses will be divided into three doses to be taken with meals.
Drug: Ferric Citrate
Auryxia® 210 mg ferric iron tablets equivalent to 1 g of FC will be supplied as 200 tablets in 400cc high-density polyethylene bottles.
Other Names:
  • Auryxia
Placebo Comparator: Control Arm
During the 12-month trial, participants will be given a fixed weight-based dose of Placebo. The full medication dose will be 3g/day for participants weighing <31 kg, 5g/day for those weighing >31 - <51 kg, and 6g/day for participants >51 kg. These doses will be divided into three doses to be taken with meals.
Drug: Placebo
Placebo to match Ferric Citrate tablets

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Tolerability of Ferric Citrate
Time Frame: 12 months
Compared with placebo, active treatment will be tolerable
12 months
iFGF23 levels
Time Frame: 12 months
Compared to placebo, active treatment with FC will lower iFGF23 levels
12 months
Safety of Ferric Citrate
Time Frame: 12 months
Comparing proportion of subjects with AE and SAE between arms
12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Effects on Transferrin Saturation (TSAT)
Time Frame: 12 months
Compared with placebo, active treatment with FC will be associated with larger increase in hemoglobin, higher TSAT and higher Ferritin from baseline
12 months
Effects on PTH and 1,25 D
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a larger decrease in PTH and larger increase in 1,25 D from baseline
12 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Effects on phosphate
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a greater reduction in 24 hours urinary phosphate and fractional excertion of phosphate
12 months
Effects on bone expression
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a greater reduction in bone expression of FGF23
12 months
Effects on calcium
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a greater incresae in serum calcium levels from baseline
12 months
Effects on bone biomarkers
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with greater reduction from baseline of bone biomarkers of turnover
12 months
Effects on cFGF23
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with greater reduction from baseline in cFGF23
12 months
GFR
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with smaller decrease in GFR over time
12 months
Osteoid thickness
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a larger decrease of osteoid thickness from baseline
12 months
Effects on 1,25 (OH) D levels
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with a greater increase from baseline in serum 1,25 (OH) D levels
12 months
Effects on Klotho
Time Frame: 12 months
Compared to placebo, active treatment with FC will be associated with greater increase from baseline in levels of Klotho
12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of California, Los Angeles

Collaborators

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Investigators

  • Principal Investigator: Isidro B Salusky, MD, University of California, Los Angeles

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 17, 2022

Primary Completion (Estimated)

October 1, 2027

Study Completion (Estimated)

November 30, 2028

Study Registration Dates

First Submitted

February 2, 2021

First Submitted That Met QC Criteria

February 2, 2021

First Posted (Actual)

February 5, 2021

Study Record Updates

Last Update Posted (Actual)

April 17, 2026

Last Update Submitted That Met QC Criteria

April 14, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • U01DK122013 (U.S. NIH Grant/Contract)
  • 1U01DK122013 (U.S. NIH Grant/Contract)
  • 22-001133 (Other Identifier: UCLA IRB)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

All de-identified clinical data, including study outcomes and participant characteristics will be submitted to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Central Repository at the completion of the study. De-identified research samples blood and urine will also be provided to the NIDDK central reporsitory

IPD Sharing Time Frame

the IPD will become available 12 months after study completion.

IPD Sharing Access Criteria

Access will be provided by National Institute of Health and any researcher will be able to request access from NIH once the data becomes available.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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