#4296 EFFECTS OF FERRIC CITRATE HYDRATE ON FIBROBLAST GROWTH FACTOR 23 AND PLATELET COUNT IN CKD AND NON-CKD PATIENTS WITH IRON DEFICIENCY ANAEMIA
Authors: Ito Kyoko , Arita Kojo , Mitobe Yuko , Akizawa Tadao , Komatsu Norio 
Published: June 2023

Abstract

Background and Aims
Iron deficiency increases the transcription and cleavage of the peptide hormone, fibroblast growth factor 23(FGF23). Elevated FGF23 has been associated with increased risk of cardiovascular events and mortality. Iron deficiency also increases platelet count (PLT) in part, and higher levels PLT are associated with arterial thrombosis in the brain. Ferric citrate hydrate (FC, Riona®, Torii Pharmaceutical Co., Ltd. Tokyo, Japan) is an oral iron-based phosphate binder for patients with chronic kidney disease (CKD) and also an iron preparation approved for treatment of iron deficiency anaemia (IDA) in Japan. A phase 3 study was conducted to investigate the efficacy and safety of FC in CKD and non-CKD patients with IDA. This study aimed to evaluate the effects of FC on intact FGF23 and c-terminal FGF23 levels, and the proportion of patients with high PLT (exceeding upper limit: &gt;35.2 × 104/µL).

Method
A randomized, open-label, multicentre, uncontrolled, 24-week study was conducted at 31 centres in Japan from July 2018 to December 2019 (JapicCTI-184000) in CKD and non-CKD patients with IDA (Hb: ≥8.0 g/dL
and &lt;11.0 g/dL, serum ferritin &lt;50 ng/mL in CKD (eGFRcre &lt;60 mL/min/1.73 m2) and &lt;12 ng/mL in non-CKD). CKD patients scheduled to initiate maintenance dialysis were excluded. Dynamic allocation was used to randomise subjects (CKD and non-CKD with Hb at baseline) to the FC-low group (500 mg [approximately 120 mg elemental iron]/day) or FC-high group (1000 mg [approximately 240 mg elemental iron]/day) (1:1). Notably, if investigators determined that sufficient iron replacement had been achieved from week 8 onwards, the study treatment was completed. For this reason, changes from baseline to week 8 were evaluated.

Results
Of 73 patients (CKD n = 42, non-CKD n = 31), 36 were allocated to the FC-low group (CKD n = 21, non-CKD n = 15) and 37 to the FC-high group (CKD n = 21, non-CKD n = 16). Baseline levels of serum ferritin, transferrin saturation (TSAT), c-terminal FGF23, intact FGF23, and PLT are shown in Table 1. Regardless of CKD status, serum ferritin and TSAT increased. After FC-low treatment, mean changes from baseline to week 8 (95% CI) in serum ferritin and TSAT were 18.8 (13.3, 24.2) ng/mL and 8.1 (4.4, 11.8) % in CKD, 17.5 (13.8, 21.3) ng/mL and 13.8 (8.7, 18.9) % in non-CKD;, they were 28.1 (13.4, 42.7) ng/mL and 8.8 (5.4, 12.1) % in CKD, 15.9 (12.1, 19.8) ng/mL and 19.9 (9.8, 30.1) % in non-CKD. After administration of FC, in both groups, intact FGF23 levels did not change, whereas c-terminal FGF23 levels decreased. Median changes (interquartile range) from baseline to week 8 of c-terminal FGF23 were -58.00 (-227.50, -12.25) RU/mL in CKD and -725.00 (-1124.00, -168.50) RU/mL in non-CKD, and -66.00 (-265.70, -27.00) RU/mL in CKD and -649.50 (-1127.00, -326.65) RU/mL in non-CKD. Serum phosphate did not change regardless of CKD status. At baseline, high PLT was observed in the FC-low group in 1 CKD case (5.0%) and 8 non-CKD cases (53.3%), and in the FC-high group in 3 CKD cases (15.8%) and 8 non-CKD cases (50.0%). In all these patients, PLT reduction to below 35.2 × 104/µL was observed until week 8.

Conclusion
In patients with IDA, administration of FC increased serum ferritin and TSAT, decreased c-terminal FGF23, and normalized PLT in patients with high PLT at baseline regardless of CKD status. FC may decrease the potential risk of cardiovascular events in CKD or non-CKD patients with IDA.