The Roxadustat (FG-4592) ameliorates tubulointerstitial fibrosis by promoting intact FGF23 cleavage

Hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) represents a novel therapeutic approach for renal anemia, a prevalent complication of chronic kidney disease (CKD). However, the effects of HIF-PHI on renal functional outcomes remain poorly characterized. Here, the potential effects of FG-4592, an orally administered HIF-PHI, on renal fibrosis were explored systematically.

In this study, a CKD rat model was established through subtotal 5/6 nephrectomy. Rats were administered either FG-4592 or vehicle control via oral gavage three times weekly for 12 consecutive weeks. Additionally, recombinant FGF23 was continuously delivered via subcutaneously implanted Alzet osmotic minipumps for 28 days.

Interestingly, we found that CKD-induced anemia was significantly ameliorated in CKD rats with FG-4592 treatment. Meanwhile, markedly alleviated histopathological changes and renal tubulointerstitial fibrosis (TIF) were observed in rats with FG-4592 administration. Notably, serum levels of intact FGF23 (iFGF23) were significantly reduced following FG-4592 administration in CKD rats. This finding was subsequently validated in CKD patients receiving Roxadustat therapy. Mechanistically, we illustrated that inhibition of the iFGF23-WNT5A pathway was the exact mechanism by which FG-4592 ameliorated TIF. Further, we also demonstrated that transcriptional activation of Furin enzyme was the exact molecular mechanism for FG-4592-mediated iFGF23 cleavage.

FG-4592 attenuates TIF through Furin-mediated proteolytic cleavage of iFGF23. These findings provide novel mechanistic insights into HIF-PHI-mediated renal protection and establish a theoretical framework for clinical translation.