A Placebo-Controlled, Randomized Trial of Enarodustat in Patients with Chronic Kidney Disease Followed by Long-Term Trial

UK kidney association clinical practice guideline: update of anaemia of chronic kidney disease

Anaemia is common in chronic kidney disease (CKD) encompassing non-dialysis dependent CKD (NDD-CKD) and dialysis dependent CKD (DD-CKD); people on peritoneal dialysis (PD) and haemodialysis (HD); and kidney transplant recipients (KTR). Iron deficiency and erythropoietin deficiency are the most common causes of anaemia in people with CKD, especially those requiring kidney replacement therapy (KRT). The Renal National Service Framework and National Institute for Health and Clinical Excellence in the UK, and Kidney Disease Improving Global Outcomes (KDIGO), all advocate treatment of anaemia in people with CKD. Blood transfusions are infrequently required, and newer therapies such as Hypoxia-Inducible Factor (HIF-PHI) stabilisers are now in current use. This guideline provides evidence based graded practice guidance on the use of iron; comments on iron deficiency without anaemia in people with CKD; provide further information on anaemia management in people with a transplant and provide guidance in the use of the new HIF-PHI drugs. It also provides audit and research recommendations.

Pharmacokinetics, Pharmacodynamics, and Safety Evaluation of the Novel HIF-PH Inhibitor Enarodustat: An Open-Label Phase I Study in Healthy Chinese Participants

BACKGROUND AND OBJECTIVES

Enarodustat is a hypoxia-inducible factor-prolyl hydroxylase inhibitor. We evaluated the pharmacokinetics, pharmacodynamics, and safety profile of domestic enarodustat (SAL-0951) and analyzed the influence of ethnic factors.

METHODS

In this phase I study, healthy Chinese participants received single and multiple oral doses (1, 5, and 15 mg) of SAL-0951 while in a fasted state. We monitored the pharmacokinetics, pharmacodynamics, and safety characteristics and analyzed the impact of ethnicity on pharmacokinetic characteristics.

RESULTS

In total, 33 healthy Chinese participants were enrolled; the mean age was 31.2 ± a standard deviation of 5.5 years. After single doses of 1, 5, and 15 mg were administered under fasted conditions, SAL-0951 was rapidly absorbed. Mean maximum plasma concentration and area under the plasma concentration-time curve from time 0 to the last quantifiable concentration increased dose proportionately from 0.14 to 2.54 μg/mL and from 0.63 to 9.50 h × μg/mL, respectively. The elimination half-life was 6.13, 6.32, and 6.74 h, respectively, in these three groups, and the mean value of apparent clearance ranged from 1.64 to 1.89 L/h. SAL-0951 was excreted mostly as the parent compound. It reached a stable concentration after 5 days of multiple-dose administration. We observed no drug accumulation or time-dependent pharmacokinetic characteristics and no significant difference in pharmacokinetic characteristics between Chinese and Japanese participants.

CONCLUSION

SAL-0951 was safe and well tolerated in healthy Chinese participants and had a linear pharmacokinetic profile. We found no ethnic differences in the pharmacokinetic characteristics of the drug between Chinese and Japanese populations.

CLINICAL TRIAL REGISTRATION

Registered at Chinadrugtrials.org.cn, registration number CTR2020245.

Hypertension Induced by Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors in Treating Anemia in Patients With Chronic Kidney Disease: A Mini-Review

Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors are a new class of agents for the treatment of anemia in chronic kidney disease (CKD). Unlike traditional treatments such as erythropoiesis-stimulating agents (ESAs), HIF-PH inhibitors are orally administered drugs and may increase endogenous erythropoietin and improve iron homeostasis. However, a significant concern is their possible side effect on blood pressure. The current mini-review summarizes the data of 26 randomized controlled (placebo or ESAs) trials on six different HIF-PH inhibitors with regard to their potential influence on blood pressure and hypertension in the management of anemia in CKD. Overall, the use of HIF-PH inhibitors was associated with a higher risk of hypertension than placebo (pooled risk ratio 1.36, 95% confidence interval [CI] 1.16-1.59), but a lower risk of hypertension than ESA treatment (pooled risk ratio 0.92, 95% CI 0.86-0.98), especially in CKD patients not undergoing dialysis (pooled risk ratio 0.85, 95% CI 0.73-0.98). This review highlights the importance of blood pressure monitoring during the treatment of HIF-PH inhibitors, especially out-of-office blood pressure measurement.

Roxadustat and Oral Iron Absorption in Chinese Patients with Anemia of Chronic Kidney Disease: A Randomized, Open-Label, Phase 4 Study (ALTAI)

INTRODUCTION

Anemia of chronic kidney disease (CKD) has a high incidence and is associated with many disease conditions. Iron dysmetabolism is an important contributor to anemia in CKD patients.

METHODS

ALTAI, a randomized, active-controlled, phase 4 trial, investigated the efficacy of roxadustat versus recombinant human erythropoietin (rHuEPO) on gastrointestinal iron absorption in patients with anemia of CKD (stage 4/5). The primary endpoint was change from baseline to day 15 in gastrointestinal iron absorption (serum iron area under the concentration-time curve; AUC0-3h) following single-dose oral iron.

RESULTS

Twenty-five patients with a mean age of 55.1 years were randomized 1:1 to roxadustat (n = 13) or rHuEPO (n = 12). Baseline iron profiles were similar between treatment groups. Change from baseline to day 15 in serum iron AUC0-3h was not statistically significantly different between the roxadustat and rHuEPO groups. Mean (SD) change from baseline in serum iron AUC0-3h was 11.3 (28.2) g × 3 h/dl in the roxadustat group and - 0.3 (9.7) g × 3 h/dl in the rHuEPO group. Roxadustat treatment was associated with decreased hepcidin and also increased transferrin, soluble transferrin receptor, and total iron-binding capacity (TIBC), with nominal significance. The proportion of patients experiencing one or more adverse events was 38.5% when treated with roxadustat and 16.7% with rHuEPO.

CONCLUSIONS

The study showed no significant difference between roxadustat and rHuEPO in iron absorption but was underpowered because of recruitment challenges.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04655027.

Effect of the Phosphate Binder Sevelamer Carbonate on the Bioavailability of Enarodustat, an Oral Erythropoiesis Stimulating Agent

Enarodustat is an orally available hypoxia-inducible factor-prolyl hydroxylase inhibitor which can correct the erythropoietic capacity and improve anemia in chronic kidney disease. Sevelamer carbonate, a non-calcium-based polymeric resin, is one of the commonly prescribed agents for the management of hyperphosphatemia in patients undergoing hemodialysis. This was an open-label, crossover study in healthy male subjects (N = 12) that evaluated the effect of sevelamer carbonate (2400 mg) on the bioavailability of enarodustat (25 mg) when the 2 drugs were administered together (Treatment B) or when enarodustat was administered 3 hours after (Treatment C) or 1 hour before (Treatment D) sevelamer carbonate compared to enarodustat alone (Treatment A). With coadministration of the 2 drugs (Treatment B), enarodustat Cmax and AUCinf reductions were 53% and 45%, respectively. For Treatment C, Cmax and AUCinf reductions were 11% and 6%, respectively, and for Treatment D the corresponding values were 8% and 20%. Thus, coadministration of enarodustat and sevelamer carbonate resulted in a substantial reduction (≈50%) in the oral bioavailability of enarodustat. However, the interaction was substantially mitigated by staggering the administration of enarodustat and sevelamer carbonate. Administration of 4 single oral doses of enarodustat 25 mg, with or without sevelamer carbonate, were safe and well tolerated in this study.

Novel anemia therapies in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Anemia is common in patients with chronic kidney disease and is associated with a high burden of morbidity and adverse clinical outcomes. In 2012, Kidney Disease: Improving Global Outcomes (KDIGO) published a guideline for the diagnosis and management of anemia in chronic kidney disease. Since then, new data from studies assessing established and emerging therapies for the treatment of anemia and iron deficiency have become available. Beginning in 2019, KDIGO planned 2 Controversies Conferences to review the new evidence and its potential impact on the management of anemia in clinical practice. Here, we report on the second of these conferences held virtually in December 2021, which focused on a new class of agents-the hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs). This report provides a review of the consensus points and controversies from this second conference and highlights areas that warrant prioritization for future research.

An updated meta-analysis on the efficacy and safety of hypoxia-inducible factor prolyl hydroxylase inhibitor treatment of anemia in nondialysis-dependent chronic kidney disease

BACKGROUND

Renal anemia, a common complication and threat factor of chronic kidney disease (CKD), has long been treated with injectable erythropoietin-stimulating agents (ESAs). As concerns regarding cardiovascular safety and erythropoietin resistance to ESAs have emerged, alternative therapies are urgently needed. Hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI), an oral agent, has been proven to be effective in improving renal anemia. However, the effects of HIF-PHIs on nondialysis-dependent CKD (NDD-CKD) have yet to be supported by updated meta-analyses.

METHODS

A meta-analysis of clinical randomized controlled trials (RCTs) on HIF-PHI treatment of NDD-CKD patients based on PubMed, EMBASE, and Cochrane databases as of July 16th, 2023, was conducted. The primary outcomes were the level of hemoglobin (Hb) postintervention and the ratio of Hb responses. Most of the analysis was conducted via RevMan 5.3 software using a random-effects model. Stata (version 15.0) was used to analyze the publication bias.

RESULTS

Twenty-two studies with a total of 7178 subjects in the HIF-PHI group, 3501 subjects in the ESA group and 2533 subjects in the placebo group were enrolled. HIF-PHIs increased the level of Hb and improved iron metabolism but were not inferior to ESAs in terms of safety.

CONCLUSIONS

HIF-PHIs may be a convenient and safe alternative to ESAs in patients with NDD-CKD and anemia.

Higher hemoglobin levels using darbepoetin alfa and kidney outcomes in advanced chronic kidney disease without diabetes: a prespecified secondary analysis of the PREDICT trial

BACKGROUND

In the primary analysis of the PREDICT trial, a higher hemoglobin target (11-13 g/dl) with darbepoetin alfa did not improve renal outcomes compared with a lower hemoglobin target (9-11 g/dl) in advanced chronic kidney disease (CKD) without diabetes. Prespecified secondary analyses were performed to further study the effects of targeting higher hemoglobin levels on renal outcomes.

METHODS

Patients with an estimated glomerular filtration rate (eGFR) 8-20 ml/min/1.73 m2 without diabetes were randomly assigned 1:1 to the high- and low-hemoglobin groups. The differences between the groups were evaluated for the following endpoints and cohort sets: eGFR and proteinuria slopes, assessed using a mixed-effects model in the full analysis set and the per-protocol set that excluded patients with off-target hemoglobin levels; the primary endpoint of composite renal outcome, evaluated in the per-protocol set using the Cox model.

RESULTS

In the full analysis set (high hemoglobin, n = 239; low hemoglobin, n = 240), eGFR and proteinuria slopes were not significantly different between the groups. In the per-protocol set (high hemoglobin, n = 136; low hemoglobin, n = 171), the high-hemoglobin group was associated with reduced composite renal outcome (adjusted hazard ratio: 0.64; 95% confidence interval: 0.43-0.96) and an improved eGFR slope (coefficient: + 1.00 ml/min/1.73 m2/year; 95% confidence interval: 0.38-1.63), while the proteinuria slope did not differ between the groups.

CONCLUSIONS

In the per-protocol set, the high-hemoglobin group demonstrated better kidney outcomes than the low-hemoglobin group, suggesting a potential benefit of maintaining higher hemoglobin levels in patients with advanced CKD without diabetes.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (identifier: NCT01581073).

Cardiac and Kidney Adverse Effects of HIF Prolyl-Hydroxylase Inhibitors for Anemia in Patients With CKD Not Receiving Dialysis: A Systematic Review and Meta-analysis

RATIONALE & OBJECTIVE

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are novel, orally administered agents for anemia management in chronic kidney disease (CKD). We evaluated the cardiac and kidney-related adverse effects of HIF-PHIs among patients with CKD and anemia.

STUDY DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING & STUDY POPULATIONS

Patients with anemia and CKD not receiving maintenance dialysis.

SELECTION CRITERIA FOR STUDIES

RCTs comparing HIF-PHIs to placebo or an erythropoiesis-stimulating agent (ESA) with primary outcomes of cardiac and kidney-related adverse events (AEs).

DATA EXTRACTION

Two independent reviewers evaluated RCTs for eligibility and extracted relevant data.

ANALYTICAL APPROACH

Dichotomous variables were pooled using the Mantel-Haenszel method and presented as risk ratios (RRs). Subgroup analyses evaluated different intervention times and HIF-PHIs, as well as phase 2 versus phase 3 trials. The certainty of findings was rated according to GRADE criteria.

RESULTS

Twenty-three studies with 15,144 participants were included. No significant difference in the risk of cardiac AEs was observed between the HIF-PHIs group and the placebo (RR, 1.02 [95% CI, 0.89-1.16]; moderate certainty) or ESA (RR, 1.06 [95% CI, 0.98-1.14]; low certainty) groups. No significant difference in the risk of kidney-related AEs was observed between the HIF-PHIs group and the placebo (RR, 1.09 [95% CI, 0.98-1.20]; moderate certainty) or ESA (RR, 1.00 [95% CI, 0.94-1.06]; low certainty) groups. The occurrence of hypertension and hyperkalemia was higher in the HIF-PHIs group than in the placebo group (RRs of 1.35 [95% CI, 1.14-1.60] and 1.25 [95% CI, 1.03-1.51], respectively; both findings had high certainty). The occurrence of hypertension was lower in the HIF-PHIs group than in the ESA group (RR, 0.89 [95% CI, 0.81-0.98]; moderate certainty).

LIMITATIONS

The reporting criteria of cardiac and kidney-related AEs and dosage of HIF-PHIs were inconsistent across trials.

CONCLUSIONS

The occurrence of cardiac or kidney-related AEs in the HIF-PHI groups were not different compared with placebo or ESA groups.

REGISTRATION

Registered at PROSPERO with registration number CRD42021228243.

Evaluation of Hemoglobin Response to Treatment With Enarodustat Using Pharmacometric Approach in Japanese Anemic Patients With Chronic Kidney Disease

Enarodustat (JTZ-951) is a hypoxia-inducible factor prolyl hydroxylase inhibitor that has been approved and marketed in Japan for patients with anemia with chronic kidney disease (CKD). The pharmacometric approach was applied to assess the relationship between plasma concentrations of enarodustat and hemoglobin (Hb) levels, and to provide information regarding the optimal use of enarodustat in clinical practice by simulations based on the pharmacokinetic and pharmacodynamic (PK/PD) model that was developed. The PK/PD data of enarodusat obtained from phase 2 and phase 3 studies in Japanese patients with CKD were well described by the models: a 1-compartment model with first-order absorption and elimination for PK, and a semimechanistic model based on transit compartment model for PD. Although several factors were identified as statistically significant covariates on the PK/PD of enarodustat, model-based simulations showed that none of them had clinically relevant impacts on the treatment effect (ie, Hb levels) of enarodustat. Hence, enarodustat treatment provides the stable Hb control with the initial dose (hemodialysis-dependent CKD: 4 mg/day, non-dialysis-dependent CKD: 2 mg/day) and maintenance dose (1-8 mg/day) to the patients with varied demographic characteristics.

Updates on Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors in the Treatment of Renal Anemia

Background

Anemia is a common complication of chronic kidney disease. The hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) is a new class of oral drugs for the treatment of renal anemia.

Summary

Clinical trials have consistently shown that HIF-PHIs can effectively increase hemoglobin in both the dialysis population and the nondialysis population. The effects of HIF-PHIs in treating renal anemia include promoting endogenous erythropoietin production and facilitating iron mobilization. Several studies suggest that the erythropoiesis effect of roxadustat is less affected by inflammation. Careful monitoring of thromboembolic events and tumor before and during HIF-PHI treatment is necessary.

Key Messages

HIF-PHIs are effective in correcting renal anemia. The long-term safety of HIF-PHIs needs to be further studied.

Effects of hypoxia-inducible factor-prolyl hydroxylase inhibitors vs. erythropoiesis-stimulating agents on iron metabolism in non-dialysis-dependent anemic patients with CKD: A network meta-analysis

OBJECTIVE

To compare the effects of five hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PHIs), two erythropoiesis-stimulating agents (ESAs), and placebo on iron metabolism in renal anemia patients with non-dialysis-dependent chronic kidney disease (NDD-CKD).

METHOD

Five electronic databases were searched for studies. Randomized controlled clinical trials comparing HIF-PHIs, ESAs, and placebo in NDD-CKD patients were selected. The statistical program used for network meta-analysis was Stata/SE 15.1. The main outcomes were the change in hepcidin and hemoglobin (Hb) levels. The merits of intervention measures were predicted by the surface under the cumulative ranking curve method.

RESULTS

Of 1,589 original titles screened, data were extracted from 15 trials (3,228 participants). All HIF-PHIs and ESAs showed greater Hb level-raising ability than placebo. Among them, desidustat demonstrated the highest probability of increasing Hb (95.6%). Hepcidin [mean deviation (MD) = -43.42, 95%CI: -47.08 to -39.76], ferritin (MD= -48.56, 95%CI: -55.21 to -41.96), and transferrin saturation (MD = -4.73, 95%CI: -5.52 to -3.94) were decreased, while transferrin (MD = 0.09, 95%CI: 0.01 to 0.18) and total iron-binding capacity (MD = 6.34, 95%CI: 5.71 to 6.96) was increased in HIF-PHIs versus those in ESAs. In addition, this study observed heterogeneity in the ability of HIF-PHIs to decrease hepcidin. Compared with darbepoetin, only daprodustat (MD = -49.09, 95% CI: -98.13 to -0.05) could significantly reduce hepcidin levels. Meanwhile, daprodustat also showed the highest hepcidin-lowering efficacy (84.0%), while placebo was the lowest (8.2%).

CONCLUSION

For NDD-CKD patients, HIF-PHIs could ameliorate functional iron deficiency by promoting iron transport and utilization, which may be achieved by decreasing hepcidin levels. Interestingly, HIF-PHIs had heterogeneous effects on iron metabolism.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=242777, Identifier CRD42021242777.

A Retrospective Study of the Perioperative Period Management of Joint Arthroplasty in Patients with Chronic Kidney Disease

OBJECTIVE

With the rising prevalence of chronic kidney disease (CKD) and the increasing demand for joint arthroplasty, the management of CKD patients in the perioperative period of joint arthroplasty has become an issue worthy of attention for orthopedic surgeons. This study aimed to explore comprehensive perioperative period management strategies for CKD patients.

METHODS

From March 2017 to August 2022, 62 patients who underwent joint arthroplasty in our hospital were included in a retrospective study, including 31 CKD patients (mean age 69.8 ± 13.4 years old) and 31 non-CKD patients (mean age 69.4 ± 14.2 years old). The outcome indicators were analyzed, including serum urea, serum creatinine, blood uric acid, hematocrit, and hemoglobin.

RESULTS

All patients included in the retrospective study had an average preoperative preparation time of 4.3 ± 2.6 days and an average hospitalization time of 11.0 ± 7.3 days. There were no significant differences in the changes in the serum urea values between the preoperative and postoperative measurements in the CKD patients or in the serum creatinine values and blood uric acid values (P > 0.05). The hemoglobin value in postoperative measurements was lower than in preoperative measurements in the CKD patients (P < 0.05). The hematocrit value in postoperative measurements was lower than in preoperative measurements in the CKD patients (P < 0.001).

CONCLUSION

Patients with CKD have distinct characteristics compared to non-CKD patients, and they generally have a higher risk for postoperative complications and adverse events. Recognition of risk factors, suitable timing of surgery, the undertaking of protective strategies, and proper management of complications are vital for managing CKD patients in the perioperative period of joint arthroplasty.

Disturbance of Hypoxia Response and Its Implications in Kidney Diseases

Significance: The disturbance of the hypoxia response system is closely related to human diseases, because it is essential for the maintenance of homeostasis. Given the significant role of the hypoxia response system in human health, therapeutic applications targeting prolyl hydroxylase-hypoxia-inducible factor (HIF) signaling have been attempted. Thus, systemically reviewing the hypoxia response-based therapeutic strategies is of great significance. Recent Advances: Disturbance of the hypoxia response is a characteristic feature of various diseases. Targeting the hypoxia response system is, thus, a promising therapeutic strategy. Interestingly, several compounds and drugs are currently under clinical trials, and some have already been approved for use in the treatment of certain human diseases. Critical Issues: We summarize the molecular mechanisms of the hypoxia response system and address the potential therapeutic implications in kidney diseases. Given that the effects of hypoxia response in kidney diseases are likely to depend on the pathological context, specific cell types, and the differences in the activation pattern of HIF isoforms, the precise application is critical for the treatment of kidney diseases. Although HIF-PHIs (HIF-PHD inhibitors) have been proven to be effective and well tolerated in chronic kidney disease patients with anemia, the potential on-target consequence of HIF activation and some outstanding questions warrant further consideration. Future Direction: The mechanism of the hypoxia response system disturbance remains unclear. Elucidation of the molecular mechanism of hypoxia response and its precise effects on kidney diseases warrants clarification. Considering the complexity of the hypoxia response system and multiple biological processes controlled by HIF signaling, the development of more specific inhibitors is highly warranted. Antioxid. Redox Signal. 37, 936-955.

Preclinical Characterization of Vadadustat (AKB-6548), an Oral Small Molecule Hypoxia-Inducible Factor Prolyl-4-Hydroxylase Inhibitor, for the Potential Treatment of Renal Anemia

Pharmacological inhibition of prolyl-4-hydroxylase domain (PHD) enzymes stabilizes hypoxia-inducible factors (HIFs), transcription factors that activate target genes that, among others, increase erythropoietin (EPO) synthesis, resulting in the production of new red blood cells (RBCs). Herein, we summarize the preclinical characteristics of the small molecule HIF prolyl-4-hydroxylase inhibitor vadadustat (AKB-6548), which is in development for the treatment of anemia in patients with chronic kidney disease (CKD). Vadadustat inhibits the enzyme activity of all three human PHD isozymes, PHD1, PHD2, and PHD3, with similar low nanomolar inhibitory constant values. PHD enzyme inhibition by vadadustat is competitive with endogenous cofactor 2-oxoglutarate and is insensitive to free iron concentration. In the human hepatocellular carcinoma cell line (Hep 3B) and human umbilical vein endothelial cells, PHD inhibition by vadadustat leads to the time- and concentration-dependent stabilization of HIF-1α and HIF-2α In Hep 3B cells, this in turn results in the synthesis and secretion of EPO; vascular endothelial growth factor is not measured at detectable levels. A single oral dose of vadadustat in rats potently increases circulating levels of EPO, and daily oral dosing for 14 days increases RBC indices in healthy rats and in the 5/6 nephrectomy model of CKD. In mice and dogs, once-daily repeat oral dosing increases hemoglobin and hematocrit. Vadadustat has a relatively short half-life in all nonclinical species evaluated and does not accumulate when administered as a single bolus dose (oral or intravenous) or upon repeat oral dosing. The pharmacological profile of vadadustat supports continued development for treatment of renal anemia. SIGNIFICANCE STATEMENT: Vadadustat (AKB-6548) is an orally bioavailable small molecule prolyl-4-hydroxylase inhibitor in development for anemia of chronic kidney disease. It is an equipotent inhibitor of the three human prolyl-4-hydroxylase domain isoforms, which activates erythropoiesis through stabilization of hypoxia-inducible factor (HIF)-1α and HIF-2α, increasing production of erythropoietin, without detectable stimulation of vascular endothelial growth factor.

Hypoxia-Inducible Factors and Diabetic Kidney Disease—How Deep Can We Go?

Diabetes is one of the leading causes of chronic kidney disease (CKD), and multiple underlying mechanisms involved in pathogenesis of diabetic nephropathy (DN) have been described. Although various treatments and diagnosis applications are available, DN remains a clinical and economic burden, considering that about 40% of type 2 diabetes patients will develop nephropathy. In the past years, some research found that hypoxia response and hypoxia-inducible factors (HIFs) play critical roles in the pathogenesis of DN. Hypoxia-inducible factors (HIFs) HIF-1, HIF-2, and HIF-3 are the main mediators of metabolic responses to the state of hypoxia, which seems to be the one of the earliest events in the occurrence and progression of diabetic kidney disease (DKD). The abnormal activity of HIFs seems to be of crucial importance in the pathogenesis of diseases, including nephropathies. Studies using transcriptome analysis confirmed by metabolome analysis revealed that HIF stabilizers (HIF-prolyl hydroxylase inhibitors) are novel therapeutic agents used to treat anemia in CKD patients that not only increase endogenous erythropoietin production, but also could act by counteracting the metabolic alterations in incipient diabetic kidney disease and relieve oxidative stress in the renal tissue. In this review, we present the newest data regarding hypoxia response and HIF involvement in the pathogenesis of diabetic nephropathy and new therapeutic insights, starting from improving kidney oxygen homeostasis.

Hypoxia-inducible factor stabilisers for the anaemia of chronic kidney disease

BACKGROUND

Anaemia occurs in chronic kidney disease (CKD) and is more prevalent with lower levels of kidney function. Anaemia in CKD is associated with death related to cardiovascular (CV) disease and infection. Established treatments include erythropoiesis-stimulating agents (ESAs), iron supplementation and blood transfusions. Oral hypoxia-inducible factors (HIF) stabilisers are now available to manage anaemia in people with CKD.

OBJECTIVES

We aimed to assess the benefits and potential harms of HIF stabilisers for the management of anaemia in people with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 22 November 2021 through contact with the Information Specialist using search terms relevant to our review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised and quasi-randomised studies evaluating hypoxia-inducible factors stabilisers compared to placebo, standard care, ESAs or iron supplementation in people with CKD were included.

DATA COLLECTION AND ANALYSIS

Five authors independently extracted data and assessed the risk of bias. Treatment estimates were summarised using random effects pair-wise meta-analysis and expressed as a relative risk (RR) or mean difference (MD), with a corresponding 95% confidence interval (CI). Evidence certainty was assessed using GRADE.

MAIN RESULTS

We included 51 studies randomising 30,994 adults. These studies compared HIF stabilisers to either placebo or an ESA. Compared to placebo, HIF stabiliser therapy had uncertain effects on CV death (10 studies, 1114 participants): RR 3.68, 95% CI 0.19 to 70.21; very low certainty evidence), and nonfatal myocardial infarction (MI) (3 studies, 822 participants): RR 1.29, 95% CI 0.31 to 5.36; I² = 0%; very low certainty evidence), probably decreases the proportion of patients requiring blood transfusion (8 studies, 4329 participants): RR 0.51, 95% CI 0.44 to 0.60; I² = 0%; moderate certainty evidence), and increases the proportion of patients reaching the target haemoglobin (Hb) (10 studies, 5102 participants): RR 8.36, 95% CI 6.42 to 10.89; I² = 37%; moderate certainty evidence). Compared to ESAs, HIF stabiliser therapy may make little or no difference to CV death (17 studies, 10,340 participants): RR 1.05, 95% CI 0.88 to 1.26; I² = 0%; low certainty evidence), nonfatal MI (7 studies, 7765 participants): RR 0.91, 95% CI 0.76 to 1.10; I² = 0%; low certainty evidence), and nonfatal stroke (5 studies, 7285 participants): RR 1.06, 95% CI 0.71 to 1.56; I² = 8%; low certainty evidence), and had uncertain effects on fatigue (2 studies, 3471 participants): RR 0.80, 95% CI 0.56 to 1.16; I² = 0%; very low certainty evidence). HIF stabiliser therapy probably decreased the proportion of patients requiring blood transfusion (11 studies, 10,786 participants): RR 0.87, 95% CI 0.76 to 1.00; I² = 25%; moderate certainty evidence), but may make little or no difference on the proportion of patients reaching the target Hb (14 studies, 4601 participants): RR 1.00, 95% CI 0.93 to 1.07; I² = 70%; low certainty evidence), compared to ESA. The effect of HIF stabilisers on hospitalisation for heart failure, peripheral arterial events, loss of unassisted dialysis vascular access patency, access intervention, cancer, infection, pulmonary hypertension and diabetic nephropathy was uncertain. None of the included studies reported life participation. Adverse events were rarely and inconsistently reported.

AUTHORS' CONCLUSIONS

HIF stabiliser management of anaemia had uncertain effects on CV death, fatigue, death (any cause), CV outcomes, and kidney failure compared to placebo or ESAs. Compared to placebo or ESAs, HIF stabiliser management of anaemia probably decreased the proportion of patients requiring blood transfusions, and probably increased the proportion of patients reaching the target Hb when compared to placebo.

Synthetic Approaches to the New Drugs Approved During 2020

New drugs introduced to the market are privileged structures that have affinities for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates (ADCs), provide insight into molecular recognition and simultaneously function as leads for the design of future medicines. This Review is part of a continuing series presenting the most likely process-scale synthetic approaches to 44 new chemical entities approved for the first time anywhere in the world during 2020.

Clinical Potential of Hypoxia Inducible Factors Prolyl Hydroxylase Inhibitors in Treating Nonanemic Diseases

Hypoxia inducible factors (HIFs) and their regulatory hydroxylases the prolyl hydroxylase domain enzymes (PHDs) are the key mediators of the cellular response to hypoxia. HIFs are normally hydroxylated by PHDs and degraded, while under hypoxia, PHDs are suppressed, allowing HIF-α to accumulate and transactivate multiple target genes, including erythropoiesis, and genes participate in angiogenesis, iron metabolism, glycolysis, glucose transport, cell proliferation, survival, and so on. Aiming at stimulating HIFs, a group of small molecules antagonizing HIF-PHDs have been developed. Of these HIF-PHDs inhibitors (HIF-PHIs), roxadustat (FG-4592), daprodustat (GSK-1278863), vadadustat (AKB-6548), molidustat (BAY 85-3934) and enarodustat (JTZ-951) are approved for clinical usage or have progressed into clinical trials for chronic kidney disease (CKD) anemia treatment, based on their activation effect on erythropoiesis and iron metabolism. Since HIFs are involved in many physiological and pathological conditions, efforts have been made to extend the potential usage of HIF-PHIs beyond anemia. This paper reviewed the progress of preclinical and clinical research on clinically available HIF-PHIs in pathological conditions other than CKD anemia.

Treatment of Anemia Associated with Chronic Kidney Disease with the HIF Prolyl Hydroxylase Inhibitor Enarodustat: A Review of the Evidence

Enarodustat, a newly developed hypoxia-inducible factor prolyl hydroxylase inhibitor, is used in clinical practice in Japan. Several clinical studies showed that enarodustat corrected and maintained hemoglobin (Hb) levels by stimulating endogenous erythropoietin production and improving iron utilization in anemic patients with chronic kidney disease, regardless of whether they were on dialysis. In addition, Phase III comparative studies demonstrated that enarodustat was non-inferior to darbepoetin alfa in controlling Hb levels. Furthermore, enarodustat was well tolerated during the treatment. Enarodustat is currently being developed in the Republic of Korea and China and is expected to be developed worldwide. This article reviews the data on enarodustat, including the findings from preclinical studies, pharmacokinetics/pharmacodynamics, and efficacy and safety results of clinical studies. This article is protected by copyright. All rights reserved.

TP0463518 (TS-143) Ameliorates Peptidoglycan-Polysaccharide Induced Anemia of Inflammation in Rats

TP0463518 (TS-143) is a competitive prolyl hydroxylase 1/2/3 pan-inhibitor, and has been shown to specifically stabilize hypoxia-inducible factor-2 alpha in the liver to increase erythropoietin production. While TP0463518 has been shown to improve renal anemia, its effect on anemia of inflammation is still unknown. In this study, we created a rat model of anemia of inflammation by administering peptidoglycan-polysaccharide (PG-PS) to Lewis rats; the PG-PS-treated rats developed anemia within 2 weeks after the PG-PS challenge. The hematopoietic effects of oral TP0463518 administration at 10 mg/kg once daily for 6 weeks were examined in this rat model. The hematocrit values in the TP0463518-treated group increased significantly from 32.8 ± 0.8 to 44.5 ± 2.1% after the treatment, which was comparable to that in the healthy control group. The change of the mean corpuscular volume following TP0463518 treatment was similar to that in the healthy control group up to week 4, and significantly higher than that in the vehicle-treated group. TP0463518 increased divalent metal transporter 1 and duodenal cytochrome b expressions in the intestine. Conversely, TP0465318 did not exert any effects on the expressions of genes involved in iron metabolism in the liver, even though TP0463518 dramatically increased erythropoietin expression. Furthermore, TP0463518 had no effect on the expressions of inflammation markers in the liver. These results suggest that TP0463518 increased iron absorption and improved anemia of inflammation without exacerbating liver inflammation. TP0463518 appears to have an acceptable safety profile and could become a useful new therapeutic option for anemia of inflammation.

Challenging patient phenotypes in the management of anaemia of chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is often complicated by anaemia, which is associated with disease progression and increased hospital visits, decreased quality of life, and increased mortality.

METHODS

A comprehensive literature search of English language peer-reviewed articles in PubMed/MedLine published between 1998 and 2020 related to the treatment of anaemia of CKD was conducted. The United States Renal Database System and Dialysis Outcomes and Practice Patterns Study (DOPPS) data reports, the Centers for Disease Control and Prevention and the US Food and Drug Administration websites, and published congress abstracts in 2020 were surveyed for relevant information.

RESULTS

Subgroups of patients with anaemia of CKD present a clinical challenge throughout the disease spectrum, including those with end-stage kidney disease, advanced age or resistance to or ineligibility for current standards of care (ie, oral or intravenous iron supplementation, erythropoietin-stimulating agents and red blood cell transfusions). In addition, those with an increased risk of adverse events because of comorbid conditions, such as cardiovascular diseases or diabetes, comprise special populations of patients with an unmet need for interventions to improve clinical outcomes. These comorbidities must be managed in parallel and may have a synergistic effect on overall disease severity.

CONCLUSIONS

Several therapies provide promising opportunities to address gaps with a standard of care, including hypoxia-inducible factor prolyl hydroxylase inhibitors, which stimulate haematopoiesis through promoting modest increases in serum erythropoietin and improved iron homeostasis. The critical issues in the management of anaemia of CKD in these challenging phenotypes and the clinical utility of new therapeutic agents in development for the treatment of anaemia of CKD should be assessed and the information should be made available to healthcare providers.

A Phase 3 Study of Enarodustat (JTZ-951) in Japanese Hemodialysis Patients for Treatment of Anemia in Chronic Kidney Disease: SYMPHONY HD Study

INTRODUCTION

Enarodustat (JTZ-951) is a new oral hypoxia-inducible factor-prolyl hydroxylase inhibitor for the treatment of anemia in chronic kidney disease (CKD). We conducted a phase 3 study to compare the efficacy and safety of enarodustat with darbepoetin alfa (DA) in Japanese anemic patients with CKD receiving maintenance hemodialysis.

METHODS

Subjects receiving maintenance hemodialysis were randomly assigned at a 1:1 ratio to receive oral enarodustat once daily or intravenous DA every week for 24 weeks with dose adjustment every 4 weeks to maintain hemoglobin (Hb) within a target range (≥10.0 to <12.0 g/dL). The primary efficacy endpoint was difference in mean Hb level between arms during the evaluation period defined as weeks 20-24 (noninferiority margin: -1.0 g/dL). Intravenous iron preparations were prohibited during the screening period and during weeks 0-4.

RESULTS

The mean Hb level of each arm during the evaluation period was 10.73 g/dL (95% confidence interval [CI]: 10.56, 10.91) in the enarodustat arm and 10.85 g/dL (95% CI: 10.72, 10.98) in the DA arm. The difference in the mean Hb level between arms was -0.12 g/dL (95% CI: -0.33, 0.10), confirming the noninferiority of enarodustat to DA. The mean Hb level of each arm was maintained within the target range during the treatment period. Increased total iron-binding capacity and serum iron and decreased hepcidin were observed through week 4 in the enarodustat arm albeit after switching from erythropoiesis-stimulating agents. No apparent safety concerns of enarodustat were observed compared with DA.

DISCUSSION/CONCLUSION

Enarodustat was noninferior to DA for the treatment of anemia in CKD patients receiving maintenance hemodialysis and was generally well tolerated over 24 weeks.

Treatment of Anemia in Kidney Disease: Beyond Erythropoietin

Anemia is common in patients with chronic kidney disease. Treatment with erythropoiesis-stimulating agents has decreased transfusion rates, but has not been consistently shown to improve cardiovascular outcomes or quality of life. Moreover, treatment to hemoglobin levels normal for the general population (13-14 g/dL) has resulted in increased cardiovascular morbidity and mortality versus lower hemoglobin targets, and some patients with chronic kidney disease do not reach these lower hemoglobin targets despite escalating doses of erythropoiesis-stimulating agents. The pathophysiology of anemia in patients with chronic kidney disease has been informed by the discovery of hypoxia-inducible factor and hepcidin pathways. Recent innovations in anemia treatment leverage knowledge of these pathways to effectively raise hemoglobin levels independent of erythropoiesis-stimulating agent administration. Several agents that stabilize hypoxia-inducible factor are undergoing or have completed phase 3 clinical trials. These agents appear to have equal efficacy as erythropoiesis-stimulating agents in raising hemoglobin levels and have not been associated with major safety signals to date. Because of the potential for off-target effects from non-anemia-related gene transcription by hypoxia-inducible factor stabilization, longer-term follow-up studies and registries will be needed to ensure safety. Agents that modulate hepcidin have undergone early clinical trials with mixed results regarding safety and efficacy in increasing hemoglobin levels. Sodium-glucose cotransporter 2 inhibitors, which also decrease hepcidin levels, have been associated with increased hemoglobin levels among patients with chronic kidney disease in clinical trials exploring proteinuria and kidney disease progression.

Current Status of Renal Anemia Pharmacotherapy-What Can We Offer Today

Chronic kidney disease (CKD) is one of the fastest-growing major causes of death internationally. Better treatment of CKD and its complications is crucial to reverse this negative trend. Anemia is a frequent complication of CKD and is associated with unfavorable clinical outcomes. It is a devastating complication of progressive kidney disease, that negatively affects also the quality of life. The prevalence of anemia increases in parallel with CKD progression. The aim of this review is to summarize the current knowledge on therapy of renal anemia. Iron therapy, blood transfusions, and erythropoietin stimulating agents are still the mainstay of renal anemia treatment. There are several novel agents on the horizon that might provide therapeutic opportunities in CKD. The potential therapeutic options target the hepcidin–ferroportin axis, which is the master regulator of iron homeostasis, and the BMP-SMAD pathway, which regulates hepcidin expression in the liver. An inhibition of prolyl hydroxylase is a new therapeutic option becoming available for the treatment of anemia in CKD patients. This new class of drugs stimulates the synthesis of endogenous erythropoietin and increases iron availability. We also summarized the effects of prolyl hydroxylase inhibitors on iron parameters, including hepcidin, as their action on the hematological parameters. They could be of particular interest in the out-patient population with CKD and patients with ESA hyporesponsiveness. However, current knowledge is limited and still awaits clinical validation. One should be aware of the potential risks and benefits of novel, sophisticated therapies.

Two long-term phase 3 studies of enarodustat (JTZ-951) in Japanese anemic patients with chronic kidney disease not on dialysis or on maintenance hemodialysis: SYMPHONY ND-Long and HD-Long studies

Enarodustat (JTZ‐951) is an oral hypoxia‐inducible factor prolyl hydroxylase inhibitor developed for treating anemia in chronic kidney disease. Two open‐label, uncontrolled phase 3 studies evaluated the 52‐week safety and efficacy of enarodustat in Japanese anemic patients with chronic kidney disease not on dialysis (n = 132) [SYMPHONY ND‐Long study] or on maintenance hemodialysis (n = 136) [SYMPHONY HD‐Long study]. The most frequent adverse events were viral upper respiratory tract infection (25.8%) followed by chronic kidney disease (8.3%) in the SYMPHONY ND‐Long study, and viral upper respiratory tract infection (49.3%) followed by contusion (16.9%) and diarrhea (16.9%) in the SYMPHONY HD‐Long study. The incidence of any adverse events did not increase over time. Mean hemoglobin levels and 95% confidence intervals were maintained within the target range (10.0–12.0 g/dl) over 52 weeks in both studies. The long‐term safety and efficacy of enarodustat were confirmed in Japanese anemic patients with chronic kidney disease.

Hypoxia-Inducible Factor Stabilization as an Emerging Therapy for CKD-Related Anemia: Report From a Scientific Workshop Sponsored by the National Kidney Foundation

The National Kidney Foundation convened an interdisciplinary international workshop in March 2019 to discuss the potential role of a new class of agents for the treatment of anemia in patients with chronic kidney disease (CKD): the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). International experts with expertise in physiology, biochemistry, structural chemistry, translational medicine and clinical management of anemia participated. Participants reviewed the unmet needs of current anemia treatment, the biology of hypoxia-inducible factor, the pharmacology of prolyl hydroxylase inhibitors, and the results of phase 2 clinical trials of HIF-PHIs among patients with both non-dialysis dependent and dialysis-dependent CKD. The results of key phase 3 clinical trials of HIF-PHIs in the public domain as of this writing are also presented in this article although they appeared after the workshop was completed. Participants in the workshop developed a number of recommendations for further examination of HIF-PHIs which are summarized in this article and include long-term safety issues, potential benefits, and practical considerations for implementation including patient and provider education.

Managing Anemia across the Stages of Kidney Disease in Those Hyporesponsive to Erythropoiesis-Stimulating Agents

BACKGROUND

Patients with CKD frequently have anemia that results from iron-restricted erythropoiesis and inflammation. Anemia of CKD is currently managed with iron supplements and erythropoiesis-stimulating agents (ESAs) to promote erythropoiesis and with RBC transfusion in severe cases. Hyporesponse to ESAs, or the need for larger than usual doses to attain a given hemoglobin (Hb) level, is associated with increased morbidity and mortality and presents a pressing clinical challenge, particularly for patients on dialysis. This paper reviews ESA hyporesponse and potential new therapeutic options in the management of anemia of CKD.

SUMMARY

The most common causes of ESA hyporesponse include iron deficiency and inflammation, and to a lesser degree, secondary hyperparathyroidism, inadequate dialysis, malnutrition, and concomitant medications. Management of ESA hyporesponse is multipronged and involves treating low level infections, ensuring adequate nutrition, and optimizing iron status and dialysis modality, although some patients can remain refractory. Inflammation directly increases production and secretion of hepcidin, contributes to an impaired response to hypoxia, and suppresses proliferation of erythroid progenitors. Coordination of renal and hepatic erythropoietin (EPO) production and iron metabolism is under the control of hypoxia-inducible factors (HIF), which are in turn regulated by HIF-prolyl hydroxylases (HIF-PHs). HIF-PHs and hepcidin are therefore attractive potential drug targets particularly in patients with ESA hyporesponse. Several oral HIF-PH inhibitors have been evaluated in patients with anemia of CKD and have been shown to increase Hb and reduce hepcidin regardless of inflammation, iron status, or dialysis modality. These sustained effects are achieved through more modest increases in endogenous EPO compared with ESAs. Key Messages: Treatments that address ESA hyporesponse remain a significant unmet clinical need in patients with anemia of CKD. New therapies such as HIF-PH inhibitors have the potential to address fundamental aspects of ESA hyporesponse and provide a new therapeutic option in these patients.

Thorough QT/QTc Evaluation of the Cardiac Safety of Enarodustat (JTZ-951), an Oral Erythropoiesis-Stimulating Agent, in Healthy Adults

This study evaluated the effect of enarodustat on cardiac repolarization in healthy subjects. Enarodustat (20 and 150 mg [supratherapeutic dose]), placebo, and moxifloxacin (positive control, 400 mg) were administered orally to males and females (N = 54) in a crossover fashion. Continuous 12-lead Holter electrocardiogram (ECG) data were obtained before and after dosing, and blood samples were obtained for pharmacokinetic assessments of enarodustat, its circulating metabolite (R)-M2, and moxifloxacin. Central tendency analysis was performed for relevant ECG parameters, the relationship between individual-corrected interval from beginning of the QRS complex to end of the T wave in the frontal plane (QTcI, the primary end point) and plasma concentrations of enarodustat and (R)-M2 were assessed, and ECG waveforms were evaluated for morphological changes. The supratherapeutic dose resulted in 7- and 9-fold higher geometric mean maximum concentrations for enarodustat and (R)-M2, respectively, than the 20 mg dose. Based on time point analysis, the upper bound of the 2-sided 90% confidence interval (CI) for QTcI did not exceed 10 milliseconds at any of the time points for either dose. Based on QTcI-concentration analysis, the slopes for enarodustat and (R)-M2 were not statistically different than 0, and the upper bounds of the 2-sided 90% CI for QTcI at the geometric mean maximum concentrations for the supratherapeutic dose were 1.97 and 1.68 milliseconds for enarodustat and (R)-M2, respectively. The lower bound of the 2-sided 90% CI for moxifloxacin was ≥5 milliseconds, demonstrating assay sensitivity. The study demonstrated no clinically relevant effect of enarodustat and (R)-M2 on cardiac repolarization. There was no evidence of any clinically significant effect on the PR interval and QRS duration, and ECG waveforms showed no new clinically relevant morphological changes.

A Phase 3 Study of Enarodustat in Anemic Patients with CKD not Requiring Dialysis: The SYMPHONY ND Study

Introduction

Enarodustat (JTZ-951) is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that might be a new therapeutic approach for managing anemia in patients with chronic kidney disease (CKD). We evaluated the efficacy (noninferiority to darbepoetin alfa [DA]) and safety of enarodustat in Japanese anemic patients with CKD not requiring dialysis.

Methods

Erythropoiesis-stimulating agent (ESA)-naïve patients and ESA-treated patients were randomized at a 1:1 ratio to receive enarodustat orally once daily or DA subcutaneously every 2 or 4 weeks for 24 weeks, respectively. Subjects in each arm had dose adjustments every 4 weeks to maintain their hemoglobin (Hb) level within the target range (10 to 12 g/dl). The primary endpoint was the difference in the mean Hb level between arms during the evaluation period defined as weeks 20 to 24 (noninferiority margin: -0.75 g/dl).

Results

The mean Hb level during the evaluation period in the enarodustat arm was 10.96 g/dl (95% confidence interval [CI]: 10.84 to 11.07 g/dl) with a difference of 0.09 g/dl (95% CI: -0.07 to 0.26 g/dl) between arms, establishing its noninferiority to DA. Nearly 90% of subjects in both arms maintained a mean Hb level within the target range. Compared with DA, enarodustat was associated with decreased hepcidin and ferritin, and increased total iron-binding capacity. There were no apparent differences in the incidence of adverse events between arms (65.4% [enarodustat], 82.6% [DA]).

Conclusions

The efficacy of enarodustat was comparable to DA in anemic patients with CKD not requiring dialysis. No new safety concerns were identified compared with DA.

JTZ-951 (enarodustat), a hypoxia-inducible factor prolyl hydroxylase inhibitor, improves iron utilization and anemia of inflammation: Comparative study against recombinant erythropoietin in rat

Anemia with inflammation-induced defective iron utilization is a pathological condition observed in patients suffering from chronic kidney disease (CKD) or chronic inflammatory disease. There is no reasonable treatment for these conditions, because the effects of erythropoiesis stimulating agents (ESAs) or iron supplementation in the treatment of anemia are insufficient. JTZ-951 (enarodustat) has been characterized as a novel, orally bioavailable inhibitor of hypoxia-inducible factor prolyl hydroxylase (HIF-PH), and has been developed as a novel therapeutic agent for anemia with CKD. In this study, the effects of JTZ-951 on iron utilization during erythropoiesis and on anemia of inflammation were compared with those of recombinant human erythropoietin (rHuEPO) using normal rat and rat model of anemia of inflammation. In normal rats, under conditions in which JTZ-951 and rHuEPO showed similar erythropoietic effect, repeated doses of JTZ-951 induced erythropoiesis while retaining the hemoglobin content in red blood cells, while administration of rHuEPO resulted in decrease in some erythrocyte-related parameters. As for iron-related parameters during erythropoiesis, JTZ-951 exhibited more efficient iron utilization compared to rHuEPO. A single dose of JTZ-951 resulted in decrease in hepcidin expression observed within 24 h after administration, but a single dose of rHuEPO did not. In a rat model of anemia of inflammation (also known as a model with functional iron-deficiency), JTZ-951 showed erythropoietic effect, in contrast with rHuEPO. These results suggest that, unlike rHuEPO, JTZ-951 stimulates erythropoiesis by increasing iron utilization, and improves anemia of inflammation.

HIF-α Prolyl Hydroxylase Inhibitors and Their Implications for Biomedicine: A Comprehensive Review

Oxygen is essential for the maintenance of the body. Living organisms have evolved systems to secure an oxygen environment to be proper. Hypoxia-inducible factor (HIF) plays an essential role in this process; it is a transcription factor that mediates erythropoietin (EPO) induction at the transcriptional level under hypoxic environment. After successful cDNA cloning in 1995, a line of studies were conducted for elucidating the molecular mechanism of HIF activation in response to hypoxia. In 2001, cDNA cloning of dioxygenases acting on prolines and asparagine residues, which play essential roles in this process, was reported. HIF-prolyl hydroxylases (PHs) are molecules that constitute the core molecular mechanism of detecting a decrease in the partial pressure of oxygen, or hypoxia, in the cells; they can be called oxygen sensors. In this review, I discuss the process of molecular cloning of HIF and HIF-PH, which explains hypoxia-induced EPO expression; the development of HIF-PH inhibitors that artificially or exogenously activate HIF by inhibiting HIF-PH; and the significance and implications of medical intervention using HIF-PH inhibitors.

Hypoxia-inducible factor-prolyl hydroxylase inhibitors in the treatment of anemia of chronic kidney disease

Hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PHIs) are a promising new class of orally administered drugs currently in late-stage global clinical development for the treatment of anemia of chronic kidney disease (CKD). HIF-PHIs activate the HIF oxygen-sensing pathway and are efficacious in correcting and maintaining hemoglobin levels in patients with non-dialysis- and dialysis-dependent CKD. In addition to promoting erythropoiesis through the increase in endogenous erythropoietin production, HIF-PHIs reduce hepcidin levels and modulate iron metabolism, providing increases in total iron binding capacity and transferrin levels, and potentially reducing the need for i.v. iron supplementation. Furthermore, HIF-activating drugs are predicted to have effects that extend beyond erythropoiesis. This review summarizes clinical data from current HIF-PHI trials in patients with anemia of CKD, discusses mechanisms of action and pharmacologic properties of HIF-PHIs, and deliberates over safety concerns and potential impact on anemia management in patients with CKD.

Iron metabolism and management: focus on chronic kidney disease

Anemia is common in patients with chronic kidney disease (CKD) and results from the dysregulation of iron metabolism and erythropoiesis. Hepcidin is a key regulator of iron availability and leads to iron sequestration during the state of iron repletion. Decreases in the level of hepcidin in the presence of hypoxia and/or iron limitation allow for greater iron availability for erythropoiesis. However, kidney excretion of hepcidin decreases as the severity of CKD increases, whereas production of hepcidin is increased under inflammatory conditions often present in patients with CKD, both of which contribute to anemia. Assessment of iron status is, therefore, essential in the treatment of anemia. However, current laboratory tests for the determination of the adequate supply of iron have many limitations, including diurnal variation in the levels of biomarkers, lack of standardized reference methods across laboratories, and confounding by the presence of inflammation. In addition, the current treatment paradigm for anemia of CKD can further disrupt iron homeostasis; for example, treatment with erythropoiesis-stimulating agents in the absence of supplemental iron can induce functional iron deficiency. Moreover, supplemental iron can further increase levels of hepcidin. Several novel therapies, including hypoxia-inducible factor prolyl hydroxylase inhibitors and hepcidin inhibitors/antagonists, have shown promise in attenuating the levels and/or activity of hepcidin in anemia of CKD, thus ensuring the availability of iron for erythropoiesis.

Hemodialysis Clearance of Enarodustat (JTZ-951), an Oral Erythropoiesis Stimulating Agent, in Patients with End-Stage Renal Disease

The dialysis clearance of enarodustat (JTZ-951) was determined in patients (N = 6) with end-stage renal disease on hemodialysis. Enarodustat (5 mg PO) was administered before (day 1) and after hemodialysis (day 8) with pharmacokinetic assessments on the 2 occasions. Dialysis clearance was based on plasma and dialysate enarodustat concentrations. Fraction of administered dose recovered in dialysate, total predialyzer and postdialyzer plasma enarodustat concentrations, and total and unbound venous plasma concentrations were determined. Hemodialysis did not significantly affect overall total concentrations with similar mean area under the plasma concentration-time curve from time 0 to infinity (coefficient of variation) of 3350 (26.4%) and 3640 (20.9%) ng · h/mL on days 1 and 8, respectively, and mean terminal half-life was 9.35 (11.9%) and 9.96 (18.7%) hours on the 2 occasions. Mean maximum concentration was somewhat lower on day 1 compared to day 8 (404 vs 559 ng/mL); the difference did not significantly affect total exposure (area under the plasma concentration-time curve from time 0 to infinity). Plasma protein binding was high (>99%) with similar binding on the 2 occasions, and total pre- and postdialyzer enarodustat concentrations were similar. Plasma unbound enarodustat concentrations decreased during dialysis, with a postdialysis rebound presumably due to re-equilibration with peripheral tissues. Mean unbound area under the plasma concentration-time curve from time 0 to infinity was marginally lower (∼22%) on day 1 compared to day 8. Dialysis clearance (0.415 L/h) was insignificant relative to dialyzer plasma flow (∼20 L/h), and the fraction of administered dose recovered in dialysate was small (6.74% of dose) with low intersubject variability (coefficient of variation, 14.7%). Thus, enarodustat can be administered regardless of dialysis schedule, and dose supplementation is not required in patients with end-stage renal disease on hemodialysis.

Long-term efficacy and safety of hypoxia-inducible factor prolyl hydroxylase inhibitors in anaemia of chronic kidney disease: A meta-analysis including 13,146 patients

WHAT IS KNOWN AND OBJECTIVE

Previous studies based on small-sample clinical data proved that short-term use of hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitors increased haemoglobin levels in anaemic patients with chronic kidney disease (CKD). However, these studies reached conflicting conclusions on iron parameters and adverse event profiles. Our meta-analysis aimed to evaluate the long-term efficacy and safety of HIF-PHD inhibitors in renal anaemia.

METHODS

Randomized controlled trials comparing treatment with HIF-PHD inhibitors versus placebo or erythropoiesis-stimulating agents (ESAs) were thoroughly searched in the PubMed, Embase, Cochrane Library and international clinical trial registries. Meta-analysis was performed on main outcomes with random effects models.

RESULTS AND DISCUSSION

A total of 30 studies comprising 13,146 patients were included. The HIF-PHD inhibitors used included roxadustat, daprodustat, vadadustat, molidustat, desidustat and enarodustat. HIF-PHD inhibitors significantly increased haemoglobin levels in comparison with placebo [weighted mean difference (WMD) 1.53, 95% confidence interval (CI) 1.39 to 1.67] or ESAs (WMD 0.13, 95% CI 0.03 to 0.22). Hepcidin, ferritin and serum iron levels were decreased, while total iron binding capacity and transferrin levels were increased in the HIF-PHD inhibitor group versus those in placebo or ESAs group. Additionally, HIF-PHD inhibitors medication was associated with cholesterol-lowering effects. As for safety, the risk of serious adverse events in the HIF-PHD inhibitor group was increased in comparison with placebo group [risk ratio (RR) 1.07, 95% CI 1.01 to 1.13], but comparable to the ESAs group (RR 1.02, 95% CI 0.94 to 1.10). Compared with placebo, the agents increased the risk of diarrhoea (1.21, 1.00 to 1.47), nausea (1.46, 1.09 to 1.97), oedema peripheral (1.32, 1.01 to 1.59), hyperkalemia (1.27, 1.05 to 1.54) and hypertension (1.34, 1.02 to 1.76). Compared with ESAs, the drugs increased the risk of vomiting (1.30, 1.02 to 1.65), headache (1.27, 1.05 to 1.53) and thrombosis events (1.31, 1.05 to 1.63).

WHAT IS NEW AND CONCLUSION

HIF-PHD inhibitors treatment effectively increased haemoglobin levels and promoted iron utilization in anaemic patients with CKD, and they were well tolerated for long-term use. In order to avoid unfavourable effects of excessive iron consumption, it was appropriate to administer HIF-PHD inhibitors in combination with iron supplements for long-term treatment.

Burden of Anemia in Chronic Kidney Disease: Beyond Erythropoietin

Anemia is a frequent comorbidity of chronic kidney disease (CKD) and is associated with a considerable burden because of decreased patient health-related quality of life and increased healthcare resource utilization. Based on observational data, anemia is associated with an increased risk of CKD progression, cardiovascular events, and all-cause mortality. The current standard of care includes oral or intravenous iron supplementation, erythropoiesis-stimulating agents, and red blood cell transfusion. However, each of these therapies has its own set of population-specific patient concerns, including increased risk of cardiovascular disease, thrombosis, and mortality. Patients receiving dialysis or those who have concurrent diabetes or high blood pressure may be at greater risk of developing these complications. In particular, treatment with high doses of erythropoiesis-stimulating agents has been associated with increased rates of hospitalization, cardiovascular events, and mortality. Resistance to erythropoiesis-stimulating agents remains a therapeutic challenge in a subset of patients. Hypoxia-inducible factor transcription factors, which regulate several genes involved in erythropoiesis and iron metabolism, can be stabilized by a new class of drugs that act as inhibitors of hypoxia-inducible factor prolyl-hydroxylase enzymes to promote erythropoiesis and elevate hemoglobin levels. Here, we review the burden of anemia of chronic kidney disease, the shortcomings of current standard of care, and the potential practical advantages of hypoxia-inducible factor prolyl-hydroxylase inhibitors in the treatment of patients with anemia of CKD.

Enarodustat: First Approval

The orally active hypoxia inducible factor-proly hydroxylase (HIF-PH) inhibitor enarodustat (ENAROY^®, Japan Tobacco) is being developed as an alternative to injectable erythropoietin stimulating agents such as epoetin and darbepoetin for the treatment of anaemia associated with chronic kidney disease (CKD). The drug is approved in Japan and clinical development is ongoing in the USA and South Korea. This article summarizes the milestones in the development of enarodustat leading to this first approval for anaemia associated with CKD.

Recommendations by the Asian Pacific society of nephrology (APSN) on the appropriate use of HIF-PH inhibitors

Renal anaemia is a common and important complication in patients with chronic kidney disease (CKD). The current standard‐of‐care treatment for renal anaemia in CKD patients involves ensuring adequate iron stores and administration of erythropoietin stimulating agents (ESA). Hypoxia inducible factor (HIF) is a key transcription factor primarily involved in the cellular regulation and efficiency of oxygen delivery. Manipulation of the HIF pathway by the use of HIF‐prolyl hydroxylase inhibitors (HIF‐PHI) has emerged as a novel approach for renal anaemia management. Despite it being approved for clinical use in various Asia‐Pacific countries, its novelty mandates the need for nephrologists and clinicians generally in the region to well understand potential benefits and harms when prescribing this class of drug. The Asian Pacific society of nephrology HIF‐PHI Recommendation Committee, formed by a panel of 11 nephrologists from the Asia‐Pacific region who have clinical experience or have been investigators in HIF‐PHI studies, reviewed and deliberated on the clinical and preclinical data concerning HIF‐PHI. This recommendation summarizes the consensus views of the committee regarding the use of HIF‐PHI, taking into account both available data and expert opinion in areas where evidence remains scarce.

The Asian Pacific society of nephrology HIF‐PHI Recommendation Committee summarizes the consensus views of the committee regarding the use of HIF‐PHI, taking into account both available data and expert opinion in areas where evidence remains scarce.

A new insight into the treatment of renal anemia with HIF stabilizer

The long-term clinical experiences with recombinant human erythropoietin (rHuEPO) and its analog derivatives have clearly proven that correction of anemia with erythropoiesis stimulating agent (ESA) not only reduces blood transfusion and improves patients’ QOL but has multiple benefits for the concurrent complications of CKD such as Cardio-Renal–Anemia (CRA) syndrome and/or malnutrition-inflammation-atherosclerosis (MIA) syndrome.

Unlike ESA, the newly available agent, hypoxia-inducible factor (HIF) stabilizer, stimulates endogenous erythropoietin (EPO) by mimicking hypoxia with HIF prolyl hydroxylase domain enzyme (HIF-PHD) inhibition. The phase 2 and 3 clinical studies have shown that HIF stabilizers are as efficacious as ESA in ameliorating renal anemia. Whether the same clinical benefits on CRA and MIA syndrome hold true in patients given HIF stabilizers is a matter for future debate. Given that HIF stabilizers act on the multiple target genes, the use of this novel agent may lead to unwanted adverse events.

Launching HIF stabilizers into the treatment of renal anemia provokes a concern about how this alternative treatment will be taken up in the daily clinical practice. However, guideline-oriented strategies on how to use HIF stabilizer is not available at this limited point due to scant clinical information. Nevertheless, this opinion-based review provides a future insight into the management of renal anemia with HIF stabilizer by reference to the past experiences with ESA. HIF stabilizers can preferably be indicated for CRA syndrome at pre-dialysis stage, ESA resistant anemia at advanced CKD stage, and perhaps for dysregulated iron metabolism akin to MIA syndrome in patients on dialysis.

Effectiveness of hypoxia-induced factor prolyl hydroxylase inhibitor for managing anemia in chronic kidney disease: a systematic review and meta-analysis

PURPOSE

To meta-statistically compare the efficiency of hypoxia-induced factor prolyl hydroxylase inhibitor on hemoglobin, ferritin, hepcidin rate, and adverse events.

METHODS

A systematic identification of literature was performed according to PRISMA guidelines on 4 academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis evaluating the influence of hypoxia-induced factors was performed for patients undergoing/not undergoing hemodialysis. The analysis evaluated the efficacy of hypoxia-induced factors on hemoglobin, ferritin, hepcidin rate, and the number of adverse events.

RESULTS

Out of 1052 records, 15 articles including 2045 patients (mean age 62.1 ± 5.4 years) were included in this review. The systematic review presents a 1a level of evidence supporting the use of hypoxia-induced factor for mediating anemia in patients with chronic kidney disease. The meta-analysis reveals medium to large beneficial effects of the hypoxia-induced factor on hemoglobin rate for patients receiving (0.72) and not receiving (1.04) hemodialysis. Moreover, the administration of hypoxia-induced factors was reported to reduce ferritin rate and the hepcidin rate, and the number of adverse events in patients with chronic kidney disease.

CONCLUSION

The current meta-analysis recommends the use of hypoxia-induced factor prolyl hydroxylase inhibitor for managing anemia in chronic kidney disease.

Effect of hypoxia-inducible factor-prolyl hydroxylase inhibitors on anemia in patients with CKD: a meta-analysis of randomized controlled trials including 2804 patients

Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) are orally active first-in-class new generation drugs for renal anemia. This extensive meta-analysis of randomized controlled trials (RCTs) was designed to provide clear information on the efficacy and safety of HIF-PHIs on anemia in chronic kidney disease (CKD) patients. Searches included PubMed, Web of Science, Ovid MEDLINE, and Cochrane Library database up to October 2019. RCTs of patients with CKD comparing HIF-PHIs with erythropoiesis-stimulating agents (ESAs) or placebo in the treatment of anemia. The primary outcome was hemoglobin change from baseline (Hb CFB); the secondary outcomes included iron-related parameters and the occurrence of each adverse event. 26 trials in 17 articles were included, with a total of 2804 dialysis or patients with CKD. HIF-PHIs treatment produced a significant beneficial effect on Hb CFB compared with the placebo group (MD, 0.69; 95% CI, 0.36 to 1.02). However, this favored effect of HIF-PHIs treatment was not observed in subgroup analysis among trials compared with ESAs (MD, 0.06; 95% CI, -0.20 to 0.31). The significant reduction in hepcidin by HIF-PHIs was observed in all subgroups when compared with the placebo group, whereas this effect was observed only in NDD-CKD patients when compared with ESAs. HIF-PHIs increased the risk of nausea (RR, 2.20; 95% CI, 1.06 to 4.53) and diarrhea (RR, 1.75; 95% CI, 1.06 to 2.92). We conclude that orally given HIF-PHIs are at least as efficacious as ESAs treatment to correct anemia short term in patients with CKD. In addition, HIF-PHIs improved iron metabolism and utilization in patients with CKD.

Effects of hypoxia-inducible factor prolyl hydroxylase inhibitors on iron regulation in non-dialysis-dependent chronic kidney disease patients with anemia: A systematic review and meta-analysis

Phase 2 and phase 3 clinical studies showed that hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) efficiently increased hemoglobin levels in both dialysis-dependent and non-dialysis-dependent chronic kidney disease (CKD) patients. However, the effects of HIF-PHIs on iron regulation have not been consistent among clinical trials. We performed a systematic review and meta-analysis of randomized controlled trials to evaluate the effects of six HIF-PHIs on iron regulation in non-dialysis CKD patients. Electronic databases were searched from inception to April 20, 2020, for eligible studies. Changes from baseline in transferrin saturation (TSAT), total iron-binding capacity (TIBC), iron, ferritin, and hepcidin levels were pooled using the inverse-variance method and presented as the mean difference (MD) or standardized MD (SMD) with 95 % confidence intervals (CIs). Meta-analysis of the included studies showed that, in non-dialysis-dependent CKD patients, HIF-PHIs decreased TSAT (MD, -4.51; 95 % CI, -5.81 to -3.21), ferritin (MD, -47.29; 95 % CI, -54.59 to -40.00) and hepcidin (SMD, -0.94; 95 % CI, -1.25 to -0.62), increased TIBC (MD, 9.15; 95 % CI, 7.08-11.22), and did not affect serum iron (MD, -0.31; 95 % CI, -2.05 to 1.42) despite enhanced erythropoiesis. This systematic review suggests that HIF-PHIs promote iron utilization in non-dialysis-dependent CKD patients. Importantly, HIF-PHIs are associated with increased transferrin levels (and TIBC), leading to reduced TSAT. Therefore, the reduction of TSAT after HIF-PHIs should not be interpreted as iron deficiency.

Efficacy and safety of hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) on anemia in non-dialysis-dependent chronic kidney disease (NDD-CKD): a systematic review and meta-analysis

PURPOSE

HIF-PHI (hypoxia-inducible factor prolyl hydroxylase inhibitor) was developed to improve renal anemia. This study was to evaluate the efficiency and safety of HIF-PHI in patients with non-dialysis-dependent chronic kidney disease (NDD-CKD).

METHODS

The literature was extracted from PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, and the Wanfang database. Statistical tests and forest plots were depicted by Review Manager Version 5.3. The primary outcome was a change in hemoglobin level from baseline (ΔHb). Secondary outcomes were changes in ferritin (ΔFerritin), hepcidin (ΔHepcidin), and transferrin saturation from baseline (ΔTSAT), and adverse events (AEs). This study is registered with PROSPERO (registration number CRD42020199656).

RESULTS

Ten trials were included. The results showed that HIF-PHI improved the ΔHb [SMD 3.03 (95% CI 2.10, 3.96), P < 0.00001] in NDD patients. HIF-PHI reduced hepcidin levels in the NDD patients [SMD - 1.44 (95% CI - 2.19-0.70), P = 0.0002]. ΔFerritin values were reduced significantly in the HIF-PHI group [SMD - 1.08 (95% CI - 1.63-0.53), P = 0.0001]. However, ΔTSAT values showed no significant difference in the HIF-PHI group compared to the placebo group [SMD - 0.23 (95% CI - 0.66-0.21), P = 0.31]. In the safety assessment, HIF-PHI did not increase adverse events significantly [RR 0.98 (95% CI 0.88-1.10), P = 0.74].

CONCLUSION

HIF-PHI improves renal anemia and iron utilization disorder in NDD-CKD patients, without significantly more adverse events.

Efficacy and safety of HIF prolyl-hydroxylase inhibitor vs epoetin and darbepoetin for anemia in chronic kidney disease patients not undergoing dialysis: A network meta-analysis

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are a new class of oral medicines being developed for the treatment of anemia in chronic kidney disease (CKD) patients. This study aimed to compare the efficacy and safety of HIF-PHI vs epoetin and darbepoetin in CKD patients with anemia not undergoing dialysis. The PubMed, Embase, Cochrane Library, Web of Science, and clinicaltrials.gov databases were searched from inception to October 2019 for randomized controlled trials investigating different agents (six HIF-PHIs, epoetin, darbepoetin, and placebo) for treating CKD patients with anemia that did not undergo dialysis. The outcomes included a change in hemoglobin (Hb) levels and all-cause mortality. A total of 19 studies were included. Compared with the placebo, except for vadadustat (mean differences: 1.12, 95 % confidence interval [CI]: ‒0.11-2.35), the other drugs significantly increased Hb levels, with mean differences of 2.46 (95 % CI: 0.93-3.99) for desidustat, 1.81 (0.87-2.75) for enarodustat, 1.68 (0.64-2.72) for molidustat, 1.66 (0.89-2.44) for epoetin, 1.63 (0.69-2.56) for darbepoetin, 1.61 (0.99-2.22) for roxadustat, and 1.55 (0.74-2.36) for daprodustat. No differences were found in the Hb level elevations among these eight drugs. Compared with the placebo, there also was no significant association between the drugs and all-cause mortality (molidustat of RR, 0.39 [95 % CI, 0.06-2.59]; roxadustat, 0.40 (0.06-2.84); enarodustat, 0.33 (0.01-16.25); desidustat, 0.34 (0.01-17.00); epoetin, 0.50 (0.18-1.42); daprodustat, 0.54 (0.09-3.31); darbepoetin, 1.03 (0.65-1.65); and vadadustat, 1.43 (0.15-13.27)). No differences were observed in the all-cause mortality among the drugs. In conclusion, these HIF-PHIs are effective and relatively tolerant for treating anemia patients with CKD not undergoing dialysis. Further research should consider the limitations of our study to evaluate the value of these HIF-PHIs in clinical settings.

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.

Hypoxia-inducible factor prolyl hydroxylase inhibitors: a paradigm shift for treatment of anemia in chronic kidney disease?

INTRODUCTION

The hypoxia-inducible factor prolyl hydroxylase (HIF-PH) pathway is responsible for regulating the biosynthesis of erythropoietin (EPO) and maintaining iron homeostasis. Investigational drugs that target the HIF-PH pathway are promising alternatives for treating anemia in Chronic Kidney Disease (CKD).

AREAS COVERED

This review summarizes recent advances focused on the clinical development of HIF-PH inhibitors (HIF-PHIs) as potentially novel therapies in the treatment of anemia in CKD based on publications available on PubMed and restricted Google searches. We provide a comparison between HIF-PHIs regarding their pharmacokinetics, dosing regimens and safety concerns, structure-activity relationships, and alterations in key laboratory parameters observed in animal models and clinical trials.

EXPERT OPINION

HIF-PHIs may be advantageous in some aspects compared to the conventional erythropoiesis-stimulating agents (ESAs). While ESAs could increase the risk of cardiovascular events due to rapid rises in ESA blood levels, HIF-PHIs have been reported to maintain EPO concentrations at levels that are closer to the normal physiological ranges. Although HIF-PHIs have been demonstrated to be relatively safe and effective in clinical trials, long-term safety data are needed in order to establish whether these therapeutic agents will lead to a major paradigm change in the treatment of anemia of CKD.

Prolyl hydroxylase inhibitors: a breath of fresh air for diabetic kidney disease?

Diabetes affects oxygen availability in the kidney, forcing the renal environment to rapidly and sustainably adapt. Physiological adaptations including activation of hypoxia inducible factor-1α and metabolic reprogramming toward pathways requiring less oxygen to maintain adenosine triphosphate production such as anaerobic glycolysis are impaired in the diabetic kidney. However, this study by Hasegawa et al. demonstrates renoprotection in diabetic kidney disease via the use of the hypoxia inducible factor-1α stabilizer enarodustat, opening a new therapeutic avenue to tackle these metabolic abnormalities.