Consensus commentary and position of the Italian Society of Nephrology on KDIGO controversies conference on novel anemia therapies in chronic kidney disease

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are new drugs developed for the treatment of anemia associated with chronic kidney disease (CKD). This class of drugs stimulates endogenous erythropoietin production and, at the same time, improves iron absorption and mobilization of iron stores (less evident with daprodustat, vadadustat and enarodustat). Several studies have been published in the last few years showing that these agents are not inferior to standard therapy in correcting anemia associated with CKD. The efficacy of HIF-PHIs is coupled with a safety profile comparable to that of standard erythropoiesis stimulating agent (ESA) treatment. However, studies with HIF-PHIs were not long enough to definitively exclude the impact of new drugs on adverse events, such as cancer, death and possibly cardiovascular events, that usually occur after a long follow-up period. Kidney Disease: Improving Global Outcomes (KDIGO) recently reported the conclusions of the Controversies Conference on HIF-PHIs held in 2021. The goal of the present position paper endorsed by the Italian Society of Nephrology is to better adapt the conclusions of the latest KDIGO Conference on HIF-PHIs to the Italian context by reviewing the efficacy and safety of HIF-PHIs as well as their use in subpopulations of interest as emerged from more recent publications not discussed during the KDIGO Conference.

Stabilizing Hypoxia-Inducible Factor to Manage Anemia in Chronic Kidney Disease: From Basic Theory to Clinical Study

Background

Anemia is one of the common complications of chronic kidney disease (CKD), and its prevalence has been arising globally. The key cause of anemia in CKD patients is the diseased kidney's reduced ability to synthesize endogenous erythropoietin (EPO), yet this is not the sole reason. Inflammatory elements, functional iron deficiency, and uremic toxins together participate in the development of anemia. According to research data, anemia is an independent risk factor for cardiovascular events, all-cause mortality, and worsening renal function and affects the clinical prognosis and quality of life of CKD patients. Regular treatments for anemia in CKD patients include the use of erythropoiesis-stimulating agents (ESAs), iron supplements, and blood transfusions.

Summary

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are novel and small-molecule pharmacological compounds that target the hypoxia-inducible factor (HIF) pathway and are another option for improving anemia in CKD patients. HIF-PHIs simulate hypoxia, stabilize HIF protein, stimulate EPO synthesis, reduce hepcidin level, boost iron utilization, induce the creation of red blood cells, and alleviate anemia. The results of several HIF-PHI phase III trials indicated that HIF-PHIs are similarly effective as ESA at raising hemoglobin concentration.

Key Messages

This article summarizes the structure of HIF and the mechanism of stabilizing HIF to improve anemia, discusses the efficacy of HIF-PHIs in CKD patients with or without dialysis, as well as emphasizes the potential safety concerns with HIF-PHIs.

Long-term treatment of chronic kidney disease patients with anemia using hypoxia-inducible factor prolyl hydroxylase inhibitors: potential concerns

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) have been approved in several countries as a supplement or even an alternative to the clinical treatment of anemia in patients with chronic kidney disease (CKD). Activation of HIF by HIF-PHIs effectively increases hemoglobin (Hb) level in CKD patients by inducing multiple HIF downstream signaling pathways. This indicates that HIF-PHIs have effects beyond erythropoietin, while their potential benefits and risks should be necessarily assessed. Multiple clinical trials have largely demonstrated the efficacy and safety of HIF-PHIs in the short-term treatment of anemia. However, in terms of long-term administration, especially over 1 year, the benefits and risks of HIF-PHIs still need to be assessed. Particular attention should be paid to the risk of kidney disease progression, cardiovascular events, retinal diseases, and tumor risk. This review aims to summarize the current potential risks and benefits of HIF-PHIs in CKD patients with anemia and further discuss the mechanism of action and pharmacological properties of HIF-PHIs, in order to provide direction and theoretical support for future studies.

Iron Supplements Concomitant within Hypoxia-Inducible Factor Prolyl Hydroxylase Domain Inhibitors in the Treatment of Chronic Kidney Disease Anemia

Background

Anemia is a common and important complication in patients with chronic kidney disease (CKD). Accordingly, the current treatment is based on erythropoiesis-stimulating agents (ESAs) and iron. Hypoxia-inducible factor (HIF) prolyl hydroxylase domain inhibitors (HIF-PHIs) have been developed to treat renal anemia through a novel mechanism. HIF-PHIs increase erythropoietin at physiologic blood concentrations and also improve the supply of hematopoietic iron. Iron is the main component of hemoglobin, and ensuring efficient iron metabolism is essential in the treatment of anemia.

Summary

HIF-PHIs may have advantages in improving iron utilization and mobilization compared to ESAs. Most HIF-PHI trials revealed a significant decline of hepcidin, increase in transferrin level and total iron binding capacity in patients. From a clinical point of view, improvements in iron metabolism should translate into reductions in iron supplementation. There are differences in the iron treatment regimentation currently used, so it is important to evaluate and timely iron supplementation across studies.

Key Messages

This review summarizes the mechanism of HIF-PHIs on improved iron metabolism and the route of iron usage in the trials for dialysis-dependent CKD and non-dialysis CKD. And this review also makes an interpretation of the clinical practice guidelines in China and recommendation by Asia Pacific Society of Nephrology.

Effects of hypoxia-inducible factor prolyl hydroxylase inhibitors versus erythropoiesis-stimulating agents on iron metabolism and inflammation in patients undergoing dialysis: A systematic review and meta-analysis

Aims

This study aimed to evaluate the effects of hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) on iron metabolism and inflammation in dialysis-dependent chronic kidney disease (DD-CKD) patients.

Methods

PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov websites were searched for randomized controlled trials (RCTs) investigating HIF-PHIs versus ESAs for DD-CKD patients.

Key findings

Twenty studies with 14,737 participants were included in the meta-analysis, which demonstrated no significant difference in the effect of transferrin saturation and ferritin between HIF-PHIs and the ESAs group (MD, 0.65; 95%CI, -0.45 to 1.75; very low certainty; SMD, -0.03; 95% CI, -0.13 to 0.07; low certainty). However, HIF-PHIs significantly increased the iron (MD, 2.30; 95% CI, 1.40 to 3.20; low certainty), total iron-binding capacity (SMD, 0.82; 95% CI, 0.66 to 0.98; low certainty), and transferrin (SMD, 0.90; 95%CI, 0.74 to 1.05; moderate certainty) levels when compared with the ESAs group. In contrast, the hepcidin level and dosage of intravenous iron were significantly decreased in the HIF-PHIs group compared with the ESAs group (MD, -15.06, 95%CI, -21.96 to -8.16; low certainty; MD, -18.07; 95% CI, -30.05 to -6.09; low certainty). The maintenance dose requirements of roxadustat were independent of baseline CRP or hsCRP levels with respect to the effect on inflammation.

Significance

HIF-PHIs promote iron utilization and reduce the use of intravenous iron therapy. Furthermore, HIF-PHIs, such as roxadustat, maintain the erythropoietic response independent of the inflammatory state. Thus, HIF-PHIs may be an alternative treatment strategy for anemia in DD-CKD patients, where ESA is hyporesponsive due to iron deficiency and inflammation.

Hypoxia-inducible factor prolyl hydroxylase inhibitors for anaemia in maintenance dialysis: a meta-analysis

BACKGROUND

Anaemia is a common complication of end-stage renal disease (ESRD) that relies on dialysis. Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) is a new class of small-molecule oral drugs for the treatment of anaemia in chronic kidney disease. They demonstrate several advantages over traditional exogenous erythropoietin (EPO). We conducted a meta-analysis of studies that compared the efficacy of HIF-PHI in erythropoiesis and iron metabolism, and its safety with EPO in maintenance dialysis patients.

METHODS

A sensitive search strategy in the PubMed, EMBASE and Cochrane databases identified all citations for randomised controlled trials (RCTs) comparing HIF-PHI agents with EPO/placebo through December 2021.

RESULTS

Fourteen RCTs were identified, which included 2738 patients. No statistical difference was found in haemoglobin increase (p = 0.37) between HIF-PHI treatment and EPO using the random-effects model. HIF-PHI administration upregulated transferrin (MD 36.12, 95% CI 27.04-45.20) and soluble transferrin receptors (sTfR) (MD 1.28, 95% CI 0.44-2.13), but did not statistically reduce hepcidin level (p = 0.37). Total and LDL-cholestrol levels were suppressed by HIF-PHI (MD - 0.99, 95% CI - 1.34 to  - 0.63) (MD - 0.99, 95% CI - 1.34 to - 0.64), while triglyceride (TG) was not different between HIF-PHI and EPO (p = 0.74). The total incident rates of treatment-emergent adverse events (TEAE) (p = 0.20) from HIF-PHI treatment were not different from those of erythropoietin, while the treatment-emergent serious adverse events (TSAE) (p = 0.02) were higher in the HIF-PHI group than those in the EPO controls with the fixed-effect model.

CONCLUSION

HIF-PHI could effectively upregulate and maintain haemoglobin levels in patients with anaemia receiving maintenance dialysis. Furthermore, HIF-PHI could elevate iron metabolism activity and utility without inducing treatment-associated serious adverse events. Robust data from larger RCTs with longer treatment duration and follow-up are needed.

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors in Patients with Renal Anemia: A Meta-Analysis of Randomized Trials

BACKGROUND

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are a new class of treatment for renal anemia in patients with chronic kidney disease (CKD). This meta-analysis was designed to evaluate their efficacy and safety.

METHOD

Eight databases were searched for randomized controlled trials (RCTs). Information about efficacy and safety was extracted and combined using random-effects or fixed-effects models, depending on heterogeneity. Risk of bias was assessed using the method recommended by the Cochrane Centre.

RESULTS

Nineteen articles on RCTs were selected, involving 3,289 participants. We found that HIF-PHIs improved the level of hemoglobin (Hb) (weighted mean difference [WMD] 1.40; 95% CI: 0.96-1.84; p < 0.001), response rate of Hb (risk ratio [RR] 5.95; 95% CI: 3.95-8.96; p < 0.001), and total iron-binding capacity (WMD 42.94; 95% CI: 31.39-54.49; p < 0.001), while reducing the level of hepcidin (WMD -40.42; 95% CI: -50.44 to -30.39; p < 0.001), ferritin (WMD -64.60; 95% CI: -78.56 to -50.64; p < 0.001), and transferrin saturation (WMD -5.57; 95% CI: -8.53 to -2.61; p < 0.001). Meanwhile, there was no evidence of effect on serum iron (WMD 1.60; 95% CI: -3.72 to 6.93; p = 0.55), nor on the incidence of adverse events (AEs) (RR 1.06; 95% CI: 0.99-1.15; p = 0.51) or of serious adverse events (SAEs) (RR 1.14; 95% CI: 0.88-1.46; p = 0.32).

CONCLUSION

HIF-PHIs ameliorate renal anemia and rectify iron metabolism in the short term without increasing the incidence of AEs and SAEs.

Current treatment practices for anemia in patients with chronic kidney disease and future opportunities with hypoxia-inducible factor prolyl hydroxylase inhibitors: a narrative review

PURPOSE

To investigate current treatment practices for anemia in patients with chronic kidney disease (CKD), issues surrounding current treatment practices, and the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) that are currently in clinical trials. Treatment of anemia in patients with CKD has traditionally included iron supplementation and erythropoiesis-stimulating agents (ESAs). However, due to adverse cardiovascular (CV) events and hypo-responsiveness to ESA therapy, new agents are currently in clinical trials to treat anemia in patients with CKD. The HIF-PHIs stimulate erythropoiesis and regulate iron metabolism and are attractive alternatives to iron supplementation and ESAs.