Chronic kidney disease is characterized as impaired renal function along with the imbalance and dysregulation of
mineral metabolism; recognized as
chronic kidney disease-mineral and bone disorder.
Hyperphosphatemia, characterized by altered
phosphate homeostasis along with elevated
fibroblast growth factor-23 and intact
parathyroid hormone, is such an alteration of
mineral metabolism. We discovered a novel inhibitor, EOS789, that interacts with several
sodium-dependent
phosphate transporters (NaPi-IIb, PiT-1, and PiT-2) known to contribute to intestinal
phosphate absorption. This inhibitor dose-dependently increased the fecal
phosphorus excretion rate and inversely decreased the urinary
phosphorus excretion rate in normal rats, suggesting inhibition of intestinal
phosphorus absorption. In rats with
adenine-induced
hyperphosphatemia, EOS789 markedly decreased the serum
phosphate,
fibroblast growth factor-23, and intact
parathyroid hormone below values found in normal control rats. Notably, this pan-
phosphate transporter inhibitor exhibited a more potent effect on serum
phosphate than a NaPi-IIb-selective inhibitor in rats with
hyperphosphatemia indicating that PiT-1 and PiT-2 play important roles in intestinal
phosphate absorption. Moreover, in a long-term study, EOS789 sustained the suppression of serum
phosphorus in parallel with
fibroblast growth factor-23 and intact
parathyroid hormone and ameliorated ectopic calcification of the thoracic aorta. Additionally, EOS789 treatment also ameliorated kidney deterioration in rats with progressive kidney injury, probably due to the strict
phosphate control. Thus, EOS789 has potent efficacy against
hyperphosphatemia and its complications and could provide a significant benefit to patients who are ineffectively treated with
phosphate binders.