ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on X

Kidney Week

Abstract: TH-PO514

Ferric Citrate Lowered Serum Phosphate Only When Elevated in Patients with Nondialysis-Dependent (NDD) CKD and Iron Deficiency Anemia (IDA)

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 305 CKD: Clinical Trials and Tubulointerstitial Disorders

Authors

  • Block, Geoffrey A., Denver Nephrology, Denver, Colorado, United States
  • Pergola, Pablo E., Renal Associates PA, San Antonio, Texas, United States
  • Uhlig, Katrin, Keryx Biopharmaceuticals, Boston, Massachusetts, United States
  • Neylan, John F., Keryx Biopharmaceuticals, Boston, Massachusetts, United States
  • Fishbane, Steven, Hofstra Northwell Health, Great Neck, New York, United States
  • Chertow, Glenn Matthew, Stanford University School of Medicine, Palo Alto, California, United States
Background

Ferric citrate (FC), an oral iron-based phosphate (P) binder approved for control of serum P in patients (pts) with CKD on dialysis, has also shown improvement in hemoglobin (Hb) and iron parameters in pts with NDD-CKD with IDA. Here, in a post-hoc analysis of a phase 3 study, we examine effects of FC on serum P in pts by different baseline (BL) P levels and stages of CKD.

Methods

233 pts with NDD-CKD and IDA were randomized 1:1 to receive FC (n=117) or placebo (n=116) for 16 weeks. FC was initiated at 3 1-g tablets/day and titrated to achieve a Hb increase ≥1 g/dL from BL (max 12 g/day). FC effects on P were examined by BL strata of P, CKD stage (per eGFR), and FGF23 (grouped by BL quartile [Q]).

Results

Decreases in P with FC treatment were greater in pts with higher BL P levels. P remained stable in pts in the lowest BL P group even with increased FC dose. Likewise, P decrease was greatest in pts with lower BL eGFR (which correlated to higher BL P) [Figure]. Similar results were seen when pts were stratified by BL FGF23 [Table]. At 16 wks, the FC dose was similar across sub-groups, suggesting BL P did not affect dosing for treatment of IDA. Multivariate linear regression analysis confirmed BL P as a strong independent predictor of change in P (p<0.0001) after adjusting for treatment, BL eGFR and BL albumin.

Conclusion

In NDD-CKD pts with IDA, the effect of FC on P reduction is dependent on the BL P, with the greatest reduction in pts with the highest serum P. These results support the use of FC in NDD-CKD pts with IDA regardless of BL P.

Mean Serum P (mg/dL) Levels Stratified by BL FGF23
i-FGF23 (pg/mL)Q1
(<87)
Q2
(87 – <134.8)
Q3
(134.8 – <211.3)
Q4
(≥211.3)
BL±SE (n)3.87±0.13 (28)3.96±0.09 (31)4.20±0.13 (25)4.83±.21 (33)
16 wks±SE (n)3.68±0.13 (22)3.58±0.11 (26)3.86±0.19 (16)3.84±0.10 (22)
Mean Δ (SE)-0.24 (0.13)-0.37 (0.16)-0.33 (0.13)-0.92 (0.26)

Funding

  • Commercial Support – Keryx Pharmaceuticals