Hypoxia induced Factor in chronic Kidney Disease: Friend or Foe?

Many studies have shown evidence that erythropoiesis-stimulating agents (ESAs), as a classic treatment for chronic kidney disease (CKD)-related anemia, have several disadvantages and may trigger various adverse events with long-term use. The hypoxiainduced factor (HIF) pathway has been intensively investigated in kidney disease, especially in CKD, as research has shown that HIF-mediated erythropoiesis might work as a potential therapeutic strategy for managing CKD-related anemia. Development of prolyl hydroxylase domain inhibitors (PHIs), as an effective HIF activator, is a valuable step toward finding a replacement for ESAs, which showed an effective erythropoiesis through a comprehensive and physiological approach by promoting erythropoietin production, increasing iron bioavailability and improving chronic inflammatory status. Heretofore no adverse events or obvious off-target effects have been reported in clinical trials of PHIs. Nevertheless, a cautious inspection with extended follow-up period is warranted to validate the safety of prolonged HIF elevation, especially considering its ambiguous role in fibrogenesis and inflammation responses and possible risks in accelerating vascular calcification and tumorigenesis. A weighed dosing strategy might be the key to circumvent the unexpected side-effect brought by pleotropic effects of HIF elevation and achieve a selective augmentation of HIF-mediated signaling pathway. New studies with longer follow-up period and adequate analysis about the risks for proinflammation, vascular calcification and tumorigenesis are needed to ensure the drugs are safe for long-term use before being widely accepted in daily clinical practice.