Hypoxia-inducible Factor Prolyl Hydroxylase Inhibitor Research Articles

Bibliometric analysis of hypoxia inducible factor prolyl hydroxylase inhibitor in anemia.

Objective: This study aimed to explore the global research status, hot topics, and future prospects in the field of the hypoxia inducible factor prolyl hydroxylase inhibitor (HIF-PHI) by bibliometric analysis. Methods: The literatures about HIF-PHI were downloaded from the Web of Science Core Collection and Pubmed database from inceptions to January.10th. 2022. The VOSviewer 1.6.18 was used to explore the bibliometric networks and research priorities of HIF-PHI. Results: A total of 409 papers about HIF-PHI were included, involving 1,674 authors from 548 institutions in 43 countries. The number of HIF-PHI literatures showed an upward trend, with steady growth from 2016 to 2020 and rapid growth in 2021. Tadao Akizawa, Masaomi Nangaku and Alexander R Cobitz published the most literatures. The United States, Japan and China contributed the most publications. The three most contributed institutions are Astellas Pharma Inc., the Showa University and Glaxosmithkline. Therapeutic Apheresis and Dialysis, American Journal of Nephrology and Clinical Pharmacology in Drug Development are the most productive journals. The main hot topics of HIF-PHI field are anemia, chronic kidney disease, hif-phi, epoetin and roxadustat. Conclusion: The United States and Japan are dominant in the field of HIF-PHI research. The discovery and clinical application of HIF-PHI is a great boon for patients with renal anemia. However, due to the short clinical application time of HIF-PHI, and its long-term efficacy and safety still need time to prove. In addition, more cooperation should be carried out between European and American countries and Asian countries to better prove the clinical value of HIF-PHI.

A PHD inhibitor prevents changes in the phosphoproteome and capillary rarefaction by CsA: treatment option for CKD?

Labes etal. analyze the phosphoproteome in a mouse model of chronic cyclosporine A nephrotoxicity and detect significant changes in the angiogenic pathway. Furthermore, they observe reduced hemoglobin levels and capillary rarefaction in the kidney. The authors show that coadministration of the hypoxia-inducible factor prolyl hydroxylase inhibitor daprodustat almost completely prevents changes of the phosphoproteome and capillary rarefaction, suggesting that prolyl hydroxylase domain enzyme inhibitors may preserve microvasculature of the kidney, which is commonly impaired in chronic kidney disease.

Roxadustat: Not just for anemia.

Roxadustat is a recently approved hypoxia-inducible factor prolyl hydroxylase inhibitor that has demonstrated favorable safety and efficacy in the treatment of renal anemia. Recent studies found it also has potential for the treatment of other hypoxia-related diseases. Although clinical studies have not yet found significant adverse or off-target effects of roxadustat, clinicians must be vigilant about these possible effects. Hypoxia-inducible factor regulates the expression of many genes and physiological processes in response to a decreased level of oxygen, but its role in the pathogenesis of different diseases is complex and controversial. In addition to increasing the expression of hypoxia-inducible factor, roxadustat also has some effects that may be HIF-independent, indicating some potential off-target effects. This article reviews the pharmacological characteristics of roxadustat, its current status in the treatment of renal anemia, and its possible effects on other pathological mechanisms.

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

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. 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. 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. 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.

Metabolic study of hypoxia-inducible factor stabilizers BAY 87-2243, MK-8617, and PT-2385 in equine liver microsomes for doping control.

A number of erythropoiesis stimulants are entering the final stage of clinical trials due to recent scientific progress in hypoxia-regulated erythropoiesis. Considering how erythropoiesis-stimulating compounds enhance the capacity of the organism to transport oxygen, they pose a great risk of being misused as performance enhancers. In this paper, we report the metabolic fate of three popular hypoxia-inducible factor-prolyl hydroxylase Inhibitors (HIF-PHI) compounds, namely, BAY 87-2243, MK-8617, and PT-2385 in equine liver microsomes using Q-Exactive high-resolution mass spectrometry. This study found 22 metabolites for BAY 87-2243 (19 phase I and three phase II), three metabolites for MK-8617 (all phase I), and five metabolites for PT-2385 (two phase I and three phase II). The major findings of the present study are as follows: (1) all three potential HIF-PHI drug candidates, namely, BAY 87-2243, MK-8617, and PT-2385 are susceptible to oxidation, producing their corresponding hydroxylated metabolites; (2) the ring dissociated metabolites were detected for BAY 87-2243 and PT-2385; (3) in the case of BAY 87-2243 and PT-2385, glucuronic acid conjugated metabolites were detected; and (4) none of the drugs produced sulfonic acid conjugated metabolites.

Hypoxia inducible factor-prolyl hydroxylase inhibitors in anemic patients with non-dialysis dependent chronic kidney disease: a meta-analysis of randomized clinical trials.

Anemia persists as a challenge in chronic kidney disease (CKD) patients. Current therapies are the injectable erythropoietin stimulating agents (ESA). Concerns have been raised regarding ESA cardiovascular safety, therefore search for an alternative, convenient and safe therapy is underway. Hypoxia inducible factors-prolyl hydroxylase inhibitors (HIF-PHI) are oral agents with promising results. Numerous small studies reported favorable effects with lack of large, powered studies. We conducted a meta-analysis of randomized clinical trials to assess the efficacy and safety of HIF-PHI in non-dialysis-dependent CKD patients. Primary outcome was hemoglobin (Hb) concentration post intervention. Secondary outcomes were all-cause mortality, MACE, and changes in iron metabolism (ferritin, hepcidin). We reported total and serious adverse effects. Data were pooled using a random effect model via RevMan 5.4 software. We identified 7 trials comprising of 8228 patients (mean age 66.5 ± 13.2years, 42% were females, 53% used iron replacement) with a mean follow-up of 52weeks. Compared with the standard of care (ESA), HIF-PHI were non-inferior for treatment of anemia, with comparable effect on mortality and major adverse cardiovascular events. HIF-PHI showed no major safety concerns. Main side effect of HIF-PHI was diarrhea. HIF-PHI might represent a safe, and convenient alternative to ESA in non-dialysis dependent CKD patients with anemia.

Elucidation of clearance mechanism of TP0463518, a novel hypoxia-inducible factor prolyl hydroxylase inhibitor: does a species difference in excretion routes exist between humans and animals?

TP0463518, a novel hypoxia-inducible factor prolyl hydroxylase inhibitor, is reportedly excreted predominantly through urinary excretion in an unchanged form in humans, with partial biliary excretion also possible. However, the clearance mechanisms remain unclear. The aim of this study was to investigate the clearance mechanisms in humans and to assess species differences in the excretion routes. TP0463518 was not metabolized in rat, dog, or human hepatocytes. TP0463518 is a substrate for human BCRP, OATP1B1, OATP1B3, and OAT3, suggesting that renal uptake by OAT3 is probably the predominant clearance route, with hepatic uptake by OATP1B1 and OATP1B3 contributing partially to clearance in humans. A species difference in excretion routes was observed. The unchanged urinary excretion rates in humans, male rats, female rats, dogs, and monkeys were 80.7%, 0.1%, 40.9%, 15.2%, and 72.6%, respectively. Urinary excretion was predominant in humans and monkeys, while only biliary excretion was observed in male rats. Uptake studies using hepatocytes showed that the hepatic uptake clearance in rats was 13.6-fold higher than that in humans. Therefore, not only reabsorption via renal tubules, but also hepatic uptake seems to be involved in the species differences in excretion routes between rats and humans.

Desidustat: First Approval.

Desidustat (Oxemia™) is an orally bioavailable, small molecule, hypoxia-inducible factor-prolyl hydroxylase (HIF-PH) inhibitor developed by Zydus Cadila for the treatment of anaemia associated with chronic kidney disease (CKD), COVID-2019 infections and chemotherapy induced anaemia. Desidustat inhibits prolyl hydroxylase domain enzymes, resulting in the stabilisation of hypoxia-inducible factor which stimulates erythropoietin production and erythropoiesis. In March 2022, desidustat received its first approval in India for the treatment of anaemia in adults with CKD who are either on dialysis or not on dialysis. Desidustat is in clinical development in China for the treatment of anaemia in patients with CKD, in Mexico for the management of COVID-2019 infections and in the USA for the treatment of chemotherapy induced anaemia. This article summarizes the milestones in the development of desidustat leading to this first approval for anaemia associated with CKD.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40265-022-01744-w.

MO756: Roxadustat Versus Erythropoietin: Comparison of Efficacy in Reversing Ventricular Remodeling in Dialysis Patients with Anemia

Abstract BACKGROUND AND AIMS Renal anemia is one of the main complications of dialysis patients, which has been identified as an important independent risk factor for left ventricular hypertrophy and progression of heart failure, as well as adverse cardiovascular outcomes. Recent studies suggest that hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) Roxadustat represents a novel pharmacological treatment for renal anemia. This study aimed to compare the role of the Roxadustat and erythropoietin in reversing ventricular remodeling in dialysis patients with anemia. METHOD This was a retrospective cohort study that compared the treatment of Roxadustat and recombinant human erythropoietin (rhEPO) in dialysis patients for at least 24 weeks from January 2016 to October 2021. A total of 182 participants underwent echocardiography at least twice every 6 months. Baseline and follow-up examinations focused on the change of cardiac structure and function (doppler echocardiography), clinical and biochemical parameters and blood pressure. Participants were treated with oral iron supplements and controlled blood pressure (target value ≤ 130/80 mmHg). RESULTS Compared with baseline, left ventricular mass index (LVMI) decreased from 139.8 ± 36.0 to 126.5 ± 35.0 g/m2 (P<0.001) in the Roxadustat hemodialysis subgroup after 6-month treatment. Left ventricular end-diastolic diameters (LVEDd) and left ventricular wall thickness (LVPWT) were both significantly improved (from 5.13 ± 0.66 to 4.92 ± 0.65 cm; P= 0.002, and from 1.12 ± 0.17 to 1.07 ± 0.13 cm; P = 0.033, respectively). There was significant difference in LVMI before and after treatment in rhEPO group (from baseline 134.3 ± 36.8 to 131.8 ± 37.5 g/m2). There was greater reduction in LVMI from baseline to 6 months in Roxadustat group (–13.3 ± 22.4 g/m2 versus –5.02 ± 21.3 g/m2 for Roxadustat versus rhEPO; P= 0.028). In the peritoneal dialysis subgroups, Roxadustat also caused a significant improvement in LVMI and LVEDd (from baseline 133.9 ± 28.0 to 118.5 ± 28.2 g/m2; P= 0.001; from baseline 5.12 ± 0.55 to 4.86 ± 0.58 cm; P = 0.002). In addition, Roxadustat increased hemoglobin, serum albumin level and TIBC, and reduced the level of blood pressure, low density lipoprotein, TC and SF in Roxadustat hemodialysis subgroup. However, there were significant differences in the changes of systolic blood pressure, diastolic blood pressure and TIBC between the two hemodialysis groups. CONCLUSION In addition to the efficacy in the treatment of renal anemia, Roxadustat was found to be closely associated with improvement of LV diastolic function in dialysis patients. Our findings may provide new insights into anemia management in dialysis patients. Prospective clinical trials are necessary to further evaluate the role of Roxadustat or other HIF-PHIs in reversing ventricular remodeling.

MO797: Roxadustat Decreases Serum Lipids Levels in Hemodialysis Patients

Abstract BACKGROUND AND AIMS The activity of hypoxia-inducible factor (HIF), an oxygen-sensitive transcription factor involved in erythropoiesis, is regulated by HIF-prolyl hydroxylases. With decreased oxygen tension, the activity of these enzymes is suppressed, resulting in increased erythropoiesis [1]. Roxadustat is an oral HIF-prolyl hydroxylase inhibitor (HIF-PHI) developed for dialysis-dependent chronic kidney disease (CKD) anemia. While the impact of HIF-PHI on mean hemoglobin (Hb) change in patients on hemodialysis (HD) has already been investigated [2], its effects on serum lipid levels have yet to be explored. Clarifying such effects is particularly important because chronic HD patients usually have lower plasma high-density lipoprotein (HDL)-cholesterol (C) levels than healthy subjects. The aim of this study is to investigate the effects of roxadustat on serum lipid levels in HD patients. METHOD Study 1: This multicenter observational cohort study investigated the demographic and clinical information of 258 patients on HD (73 women and 185 men) who were being treated for anemia by HIF-PHI between 1 February 2020 and 31 May 2021, at Zenjinkai Group dialysis centers in Japan. Study 2: This study evaluated the efficacy of roxadustat in 24 patients (3 women and 21 men) for HD-dependent CKD anemia and dyslipidemia >24 weeks. RESULTS Study 1: The mean age and HD periods were 71.2 ± 12.2 and 5.5 ± 6.6 years, respectively. The patient's CKDs were diabetic nephropathy (n = 72; 27.9%), chronic glomerular nephritis (CGN) (n = 36; 14%), nephrosclerosis (n = 32; 12.4%) and other pathologies (n = 118; 45.7%). HIF-PH inhibitors used for patients on HD were roxadustat (n = 105), daprodustat (n = 117), vadadustat (n = 14) and enadustat (n = 22). Study 2: The mean age and HD periods were 76.5 ± 7.7 and 5.3 ± 3.9 years, respectively. The patient's CKDs were CGN (n = 6; 25%), nephrosclerosis (n = 6; 25%), diabetic nephropathy (n = 4; 16.7%), unknown pathologies (n = 4; 16.7%) and others (n = 4; 16.7%). Roxadustat treatment did not lead to a significant change in mean Hb values (from 10.4 ± 0.8 to 10.5 ± 0.9 g/dL). There were no significant changes in mean triglycerides (TG), transferrin saturation (TSAT) or ferritin. However, there was a statistically significant decrease (P < .001) in mean total cholesterol (TC) (from 144.0 ± 35.6 to 121.3 ± 38.5 mg/dL), low-density lipoprotein (LDL)-C (from 79.8 ± 26.6 to 62.8 ± 26.2 mg/dL) and HDL-C (from 45.0 ± 12.6 to 38.4 ± 11.9 mg/dL). Furthermore, there were also significant increases in mean serum iron (from 68.1 ± 17.4 to 81.8 ± 31.1 μg/dL; P = .01) and the mean total iron-binding capacity (TIBC) (from 220.0 ± 46.7 to 265.1 ± 54.7 μg/dL; P < .001). Case report: A 56-year-old woman who had undergone HD for 13 years due to CKD due to diabetic nephropathy was hospitalized with cerebral infraction, peripheral arterial disease, heart failure and ischemic heart disease. The patient was treated with percutaneous coronary intervention (PCI) and started on 100 mg of roxadustat 3 times a week. After roxadustat treatment, the following parameters increased: Hb (from 10.7 to 10.8 g/dL), ferritin (from 74 to 103 ng/mL) and TIBC (from 204 to 223 μg/dL). On the other hand, the following parameters decreased: TC (from 325 to 125 mg/dL), TG (from 318 to 165 mg/dL), HDL-C (from 41 to 33 mg/dL) and LDL-C (from 227 to 55 mg/dL). The patient was discharged from the hospital after 3 months. CONCLUSION Roxadustat treatment improves iron metabolism, keeps Hb levels stable and significantly decreases mean LDL-C and HDL-C. Therefore, this drug may have useful effects on dyslipidemia in patients on HD.

MO536: Cardiovascular Events in Patients With Anemia Associated With Non–Dialysis-Dependent Chronic Kidney Disease: Regional Analysis of Patients not Previously Treated With Erythropoiesis-Stimulating Agents in The PRO2TECT Trial

Abstract BACKGROUND AND AIMS Vadadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor being investigated for treatment of anemia due to chronic kidney disease (CKD). In global phase 3 trials, vadadustat has demonstrated non-inferiority to darbepoetin alfa for time to major adverse cardiovascular event (MACE) in patients with dialysis-dependent CKD (INNO2VATE trials), but not with non–dialysis-dependent CKD (NDD-CKD; PRO2TECT trials) [1,2]. In a prespecified subgroup analysis of the PRO2TECT trials, no difference in cardiovascular safety was observed in the USA, but a higher risk of MACE was found for patients treated with vadadustat outside the USA.1 We investigated regional differences in MACE in patients previously untreated with erythropoietin-stimulating agents (ESAs) in the PRO2TECT trial. METHOD Two phase 3, open-label, randomized, active-controlled clinical trials comparing vadadustat with darbepoetin alfa were conducted in North America, Latin America, Europe, Africa, and the Asia-Pacific region. This post hoc analysis evaluated MACE in patients in the PRO2TECT trial not treated with ESAs within 8 weeks of enrollment (correction trial; NCT02648347) and who received ≥1 dose of trial drug, stratified by region (USA versus Europe versus non-USA/non-Europe). MACE was defined as a composite of death from any cause, nonfatal myocardial infarction, or nonfatal stroke. Expanded MACE was defined as MACE plus hospitalization for heart failure or thromboembolic event, excluding vascular access failure. RESULTS A total of 1748 ESA-untreated patients receiving ≥1 dose of study drug were enrolled in the PRO2TECT trial, including 1058 patients in the USA, 139 in Europe and 551 outside the USA and Europe. Patients in the non-USA/non-European countries were younger and had a lower mean eGFR than patients in the USA or Europe. Furthermore, 34.7% of patients randomized to vadadustat had a baseline eGFR <10 mL/min/1.73 m2 versus 24.0% of patients randomized to darbepoetin alfa in the non-USA/non-European countries. The hazard ratio for MACE in the overall population for vadadustat versus darbepoetin alfa was 1.16 [95% confidence interval (CI) 0.96–1.41]. When analyzed by region, higher event rate for MACE was observed in the vadadustat arm in the non-USA/non-European countries compared with the USA and Europe (Table 1). The higher event rates for MACE in the non-USA/non-European countries were driven by 21 excess MACEs reported in the vadadustat group. Many deaths in the non-USA/non-European countries were related to kidney failure (n = 25/43 in the vadadustat group; n = 20/30 in the darbepoetin alfa group; Table 2), and were concentrated in Brazil and South Africa, countries that enrolled a higher proportion of patients with end-stage kidney failure who may not have had access to dialysis. The adverse event profiles for vadadustat and darbepoetin alfa were similar across regions. CONCLUSION Regional differences in time to first MACE were observed in patients with NDD-CKD who were not previously treated with ESAs and randomized to receive vadadustat or darbepoetin alfa as part of the PRO2TECT trial. The higher event rate in the vadadustat group in non-USA/non-European countries may have been related to randomization imbalances and/or design and methodological issues. These findings should help inform care providers as they assess the overall safety of vadadustat for the treatment of anemia associated with NDD-CKD.

MO532: Cardiovascular Events in Patients With Non–Dialysis-Dependent Chronic Kidney Disease and Anemia: Regional Analysis of Patients Previously Treated With Erythropoiesis-Stimulating Agents in the PRO2TECT Trial

Abstract BACKGROUND AND AIMS Vadadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor being investigated for the treatment of anemia due to chronic kidney disease (CKD). In global phase 3 trials, vadadustat has demonstrated non-inferiority to darbepoetin alfa for time to major adverse cardiovascular event (MACE) in patients with dialysis-dependent CKD (INNO2VATE trials), but not with non–dialysis-dependent CKD (NDD-CKD; PRO2TECT trials) [1, 2]. In a prespecified subgroup analysis of the PRO2TECT trials, a difference in the relative safety between vadadustat and darbepoetin alfa was observed between the US and non-US regions [1]. We investigated regional differences in MACE in patients with NDD-CKD-administered vadadustat and darbepoetin alfa who were previously treated with erythropoietin-stimulating agents (ESAs) in the PRO2TECT trials. METHOD Two phase 3, open-label, randomized, active-controlled clinical trials comparing vadadustat with darbepoetin alfa were conducted in North America, Latin America, Europe, Africa, and the Asia-Pacific region. This post hoc analysis evaluated MACE in patients in the PRO2TECT trial who were actively maintained on ESAs at study entry with ≥1 dose received within 6 weeks before or during screening (Conversion trial; NCT02680574) and who received ≥1 dose of trial drug, stratified by region (USA versus Europe versus non-US/non-Europe). MACE was defined as a composite of death from any cause, nonfatal myocardial infarction or nonfatal stroke. Expanded MACE was defined as MACE plus hospitalization for heart failure or thromboembolic event, excluding vascular access failure. RESULTS A total of 1723 ESA-treated patients were randomized in the conversion trial of the PRO2TECT program and received ≥1 dose of study drug, including 665 patients in the USA, 444 in Europe, and 614 outside the USA and Europe. Europe had a lower proportion of patients with diabetes and more patients who had received intravenous (IV) iron, while patients in the non-US/non-European region were younger and had a lower prevalence of cardiovascular (CV) disease. A higher proportion of patients in Europe were using darbepoetin alfa at baseline than in other regions (59%–63% versus 14%–28%), though ESA dose was lower (57–61 versus 93–149 IV epoetin equivalent U/kg/week). The hazard ratio for MACE in the overall population for vadadustat versus darbepoetin alfa was 1.16 (95% CI 0.93–1.45). Across regions, event rates were similar in the vadadustat groups, but event rates in the darbepoetin alfa group were lower in Europe compared with the US and non-US/non-Europe (Table 1), which was driven by fewer total deaths (non-CV and CV) reported in Europe in the darbepoetin alfa arm (n = 24/220) compared with the vadadustat arm (n = 38/224) (Table 2). Additional post hoc analyses of MACE accounting for several baseline characteristics, including ESA dose, did not alter the outcomes of the study. CONCLUSION Regional differences in time to first MACE were observed in patients with NDD-CKD who were treated with ESA and randomized to receive vadadustat or darbepoetin alfa as part of the PRO2TECT program. It remains unclear if the lower risk of MACE observed in Europe with the darbepoetin alfa group was related to differences in unobserved baseline characteristics, regional treatment practices, methodological reasons or chance.

MO582: Impaired HIF-1 Regulation in Skeletal Muscle of Patients With Advanced-Stage Chronic Kidney Disease

Abstract BACKGROUND AND AIMS Tiredness and fatigue are common symptoms in patients with chronic kidney disease (CKD), but their underlying mechanisms are unknown and treatments unavailable. Patients with CKD display abnormalities along the entire oxygen cascade, with impaired diffusive and convective oxygen transport, thus contributing to a reduced tissue oxygen supply. Hypoxic adaptation is largely regulated by hypoxia-inducible factor 1 (HIF-1α), encoded by the HIF-1Α gene [1], and peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α). In response to hypoxia or anemia, the muscle HIF-1α target genes increase oxygen transport through angiogenesis, responsiveness to insulin, cell proliferation and apoptosis/survival [2]. PGC-1α controls the expression of genes involved in mitochondrial biogenesis, energy homeostasis and glucose metabolism. PGC-1α is correlated with a total-body aerobic capacity [3], and its decrease has been detected in muscles of elderly persons and type 2 diabetes patients [3,4]. We hypothesized that desensitization of the HIF-1α driven oxygen-sensing mechanisms occurs in CKD patients. METHOD HIF-1α, PGC1α gene and protein expression, studied by Rt–PCR and immunohistochemistry, were assessed in the rectus abdominis muscle biopsies from 31 CKD patients with non-dialysis CKD 5 (18 M/13 F, eGFR 8 ± 1 mL/min) and were compared with those obtained in 10 subjects with normal renal function (7M/3F). HIF-1α, PGC1α expression was studied also in C2C12 myotubes exposed to 10% normal serum or uremic serum (US) for 48 h. In addition, mitofusin-2 (MFN2), nuclear factor erythroid 2-related factor 2 (NRF2), and oxidative phosphorylation (OXPHOS) related to mitochondria integrity were monitored by Rt–PCR and/or western blot. Changes in the membrane potential were quantified by JC1 staining and fluorimeter analysis. RESULTS Despite anemia (Hb 9.5 ± 1 g/dL), HIF-1α mRNA was severely blunted in the muscle of CKD patients, as well as PGC1α that resulted down-regulated in 62.5% of them (P < 0.05) (Fig. 1). Log HIF-1α mRNA was directly related to log eGFR (r = 0.632, P < 0.02), suggesting that the hypoxic response in muscle progressively down-regulates as the renal function declines. In cultured myotubes, US decreases PGC1α, HIF1α, MFN2, NRF2 and OXPHOS and membrane potential (P < 0.05–0.01). CONCLUSION In patients with non-dialysis CKD, PGC1α and HIF1α are down-regulated, as well as in an in vitro model that resembles the uremic milieu. On the one hand, these findings are in keeping with impaired oxidative metabolism in the advanced stage of CKD, while on the other hand, they may account for the fatigue often referred by these patients. Moreover, our study suggests that the HIF prolyl hydroxylase inhibitor (HIF-PHIs), currently in clinical development, might be targeted on muscle metabolism and function and tested in the treatment of myopathy and fatigue in CKD.

Inhibition of hypoxia-inducible factor-prolyl hydroxylation protects from cyclophosphamide-induced bladder injury and urinary dysfunction.

Disruption of the blood-urine barrier can result in acute or chronic inflammatory bladder injury. Activation of the oxygen-regulated hypoxia-inducible factor (HIF) pathway has been shown to protect mucosal membranes by increasing the expression of cytoprotective genes and by suppressing inflammation. The activity of HIF is controlled by prolyl hydroxylase domain (PHD) dioxygenases, which have been exploited as therapeutic targets for the treatment of anemia of chronic kidney disease. Here, we established a mouse model of acute cyclophosphamide (CYP)-induced blood-urine barrier disruption associated with inflammation and severe urinary dysfunction to investigate the HIF-PHD axis in inflammatory bladder injury. We found that systemic administration of dimethyloxalylglycine or molidustat, two small-molecule inhibitors of HIF-prolyl hydroxylases, profoundly mitigated CYP-induced bladder injury and inflammation as assessed by morphological analysis of transmural edema and urothelial integrity and by measuring tissue cytokine expression. Void spot analysis to examine bladder function quantitatively demonstrated that HIF-prolyl hydroxylase inhibitor administration normalized micturition patterns and protected against CYP-induced alteration of urinary frequency and micturition patterns. Our study highlights the therapeutic potential of HIF-activating small-molecule compounds for the prevention or therapy of bladder injury and urinary dysfunction due to blood-urine barrier disruption.NEW & NOTEWORTHY Disruption of the blood-urine barrier can result in acute or chronic inflammatory bladder injury. Here, we demonstrate that pharmacological inhibition of hypoxia-inducible factor (HIF)-prolyl hydroxylation prevented bladder injury and protected from urinary dysfunction in a mouse model of cyclophosphamide-induced disruption of the blood-urine barrier. Our study highlights a potential role for HIF-activating small-molecule compounds in the prevention or therapy of bladder injury and urinary dysfunction and provides a rationale for future clinical studies.

Inflammation at High Altitude and Potential Links to Physiological Responses to Hypoxia

Inflammation plays a critical role in the physiological response to hypoxic stress. Evolutionary conserved inflammatory responses to oxygen limitation promote adaptation to the hypoxic environment. However, these responses may also become maladaptive during chronic exposure if not properly resolved, possibly contributing to pathologies such as Acute or Chronic Mountain Sickness. We hypothesize that pro‐inflammatory gene expression increases upon acute high‐altitude exposure, followed by a subsequent blunting of the inflammatory profile with acclimatization. We compared the inflammatory profiles in whole blood samples collected in the morning during fasting at sea level and after one and three nights at high altitude (3800 m elevation) in 15 healthy sojourners (5 women, 10 men). RNA sequencing was coupled with a nanoString Human Inflammatory Panel. Previously, we found key components of the TLR4 signaling pathway upregulated under acute high‐altitude exposure. To complement this, we found that IL8, a chemotactic cytokine that induces neutrophil recruitment, was significantly upregulated upon the first and third day at high altitude, and larger increases in IL8 may be associated with lower oxygen saturation (SpO2) at high altitude (R= ‐0.51; p=0.05). Additionally, FASLG, which is essential for immune system regulation, was associated with both SpO2 (R=0.68; p<0.01) and AMS score (R= ‐0.71; p<0.01) at high altitude. The upregulation of TLR4 signaling pathway genes observed during high‐altitude exposure in vivo suggested that hypoxia may exacerbate responses to inflammatory stimuli. To test this, we cultured whole blood in the presence of normoxia or hypoxia with or without a lipopolysaccharide (LPS) stimulus for 24 hours. Cultures were further treated with DMOG (HIF prolyl hydroxylase inhibitor), PX‐478 (HIF inhibitor), or media (control) to determine if any of these outcomes were HIF‐dependent. Preliminary data suggests that, in the presence of both inflammatory stimuli (LPS and hypoxia), TNF production was exacerbated (p=0.03). However, when HIF was inhibited with PX‐478, this exacerbated response was mitigated. Additionally, we found that DMOG abrogated TNF, IL6, and IL8 production in all treatments, suggesting a key role of prolyl hydroxylase activity in inflammation. In conclusion, our results indicate that acute high‐altitude exposure may cause an initial priming of the innate immune system with a synergistic TLR4‐induced sensitization to subsequent inflammatory stimuli and neutrophil activation and recruitment. In the case that the inflammatory response is not properly blunted during acclimatization, this may lead to the development of hypoxia‐induced pathologies. This may be particularly important in the context of pulmonary diseases if hypoxemia initiates an exacerbated inflammatory response to infection.

Clinical parameters among patients in Japan with anemia and non-dialysis-dependent chronic kidney disease with and without diabetes mellitus who received roxadustat

BackgroundRoxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor for treating anemia of chronic kidney disease (CKD). This post hoc analysis of a Japanese, open-label, partially randomized, phase 3 study in patients with non-dialysis-dependent (NDD) CKD evaluated disease state–related parameters among patients with and without diabetes mellitus who received roxadustat. In the 1517-CL-0310 study (NCT02988973), roxadustat was noninferior to darbepoetin alfa for change in average hemoglobin levels at Weeks 18–24 from baseline who received roxadustat.MethodsPatients enrolled in the 1517-CL-0310 study who received roxadustat were included in this post hoc analysis. Hematologic (hemoglobin, reticulocyte/erythrocyte ratio, mean corpuscular volume [MCV], and mean corpuscular hemoglobin [MCH]), iron-related (ferritin, total iron-binding capacity, transferrin, ceruloplasmin, and hepcidin), metabolic (HbA1c, glycated albumin, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol), and renal (eGFR) parameters were summarized descriptively by visit through Week 52.ResultsAmong 201 included patients, 105 (52.2%) and 96 (47.8%) were in the Diabetes and No Diabetes subgroups, respectively. There were no clinically meaningful differences through Week 52 for most hematologic, iron-related, metabolic, or renal parameters between patients in the Diabetes and No Diabetes subgroups. MCV and MCH remained lower and HbA1c and glycated albumin remained higher in patients in the Diabetes subgroup through Week 52. Both subgroups experienced a similar benefit from roxadustat in maintaining hemoglobin levels in the target range of 10–12 g/dL.ConclusionRoxadustat maintained hemoglobin levels in the target range with similar clinical parameters irrespective of diabetes mellitus presence at baseline.

Desidustat in Anemia due to Non-Dialysis-Dependent Chronic Kidney Disease: A Phase 3 Study (DREAM-ND)

Background: Desidustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, is being developed to treat anemia in patients with chronic kidney disease (CKD) without dialysis dependency. Methods: In total, 588 patients with a clinical diagnosis of anemia due to CKD without dialysis need and with baseline hemoglobin of 7.0–10.0 g/dL (inclusive) were randomized in a 1:1 ratio to receive either desidustat 100 mg oral tablets thrice a week for 24 weeks or biosimilar darbepoetin subcutaneous injection 0.75 μg/kg once in 2 weeks for 24 weeks. The primary outcome was the change from baseline in hemoglobin to evaluation period of Weeks 16–24. Key secondary outcomes included the number of patients with hemoglobin response, changes in the hepcidin levels, changes in the vascular endothelial growth factor (VEGF) levels, and changes in the lipid and lipoprotein profiles. Results: Hemoglobin change from baseline to Weeks 16–24 was 1.95 g/dL in the desidustat group and 1.83 g/dL in the darbepoetin group (difference: 0.11 g/dL; 95% CI: −0.12, 0.34), which met prespecified non-inferiority margin (−0.75 g/dL). The hemoglobin responders were significantly higher (p = 0.0181) in the desidustat group (196 [77.78%]) compared to the darbepoetin group (176 [68.48%]). The difference of change in hepcidin from baseline to Week 12 and Week 24 (p = 0.0032 at Week 12, p = 0.0016 at Week 24) and the difference of change in low-density lipoprotein from baseline to Week 24 (p value = 0.0269) between the two groups was statistically significant. The difference of change from baseline in VEGF to Weeks 12 and 24 between the two groups was not statistically significant. Conclusion: Desidustat is non-inferior to darbepoetin in the treatment of anemia due to non-dialysis dependent CKD and it is well-tolerated.

Desidustat in Anemia due to Dialysis-Dependent Chronic Kidney Disease: A Phase 3 Study (DREAM-D)

Background: A phase 3 study to assess the efficacy and safety of the desidustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, against the epoetin alfa for the treatment of anemia in patients with chronic kidney disease (CKD) with dialysis dependency. Methods: DREAM-D was a phase 3, multicenter, open-label, randomized, active-controlled clinical study conducted across 38 centers in India. A total of 392 patients with clinical diagnosis of anemia due to CKD with dialysis need (Erythrocyte Stimulating Agent [ESA] naïve or prior ESA users) and with baseline hemoglobin levels of 8.0–11.0 g/dL (inclusive) were randomized in a 1:1 ratio to receive either desidustat oral tablets (thrice a week) or epoetin alfa subcutaneous injection for 24 weeks to maintain a hemoglobin level of 10–12 g/dL. The primary endpoint was to assess the change in the hemoglobin level between the desidustat and the epoetin alfa groups from the baseline to evaluation period week 16–24. The key secondary efficacy endpoint was the number of patients with hemoglobin response. Results: The least square mean (standard error) change in hemoglobin from the baseline to week 16–24 was 0.95 (0.09) g/dL in the desidustat group and 0.80 (0.09) g/dL in the epoetin alfa group (difference: 0.14 [0.14] g/dL; 95% confidence interval: −0.1304, 0.4202), which met the prespecified noninferiority margin. The number of hemoglobin responders was significantly higher in the desidustat group (106 [59.22%]) when compared to the epoetin alfa group (89 [48.37%]) (p = 0.0382). The safety profile of the desidustat oral tablet was comparable with the epoetin alfa injection. There were no new risks or no increased risks seen with the use of desidustat compared to epoetin alfa. Conclusion: In this study, desidustat was found to be noninferior to epoetin in the treatment of anemia in CKD patients on dialysis and it was well-tolerated. Clinical Trial Registry Identifier: CTRI/2019/12/022312 (India).

Resistance to Erythropoiesis-Stimulating Agents among Patients on Hemodialysis Is Typically Transient

Introduction: This study examines factors associated with erythropoiesis-stimulating agent (ESA) hyporesponsiveness, the duration of ESA hyporesponsiveness, the frequency of new episodes, and variation across countries. Methods: We used international Dialysis Outcomes and Practice Patterns Study data from 2015 to 2018 (N = 26,656) to investigate changes in ESA Resistance Index (ERI), calculated as epoetin dose divided by [hemoglobin × body weight] in patients on hemodialysis. We illustrated the proportion of patients who moved to other ERI quintiles over 12 months, and we studied the incidence and duration of ESA resistance. We examined case-mix factors associated with quintiles of ERI. Results: Most patients migrated out of their original ERI quintile within 4 months. Only 22% of patients in the top quintile of ERI at baseline (4.4% of all patients) remained in the top quintile during all 12 months of follow-up. A total of 42% of patients manifested an upper-quintile ERI during at least 1 month. Median duration of a new episode of ESA resistance was 2 months. Catheter hemoaccess, elevated C-reactive protein, lower transferrin saturation, lower serum albumin concentration, and recent hospitalization occurred more frequently among patients in the highest ERI quintile at baseline. ERI values were highest in the USA, Italy, and Mideastern nations and lowest in Russia and Japan. Discussion/Conclusion: It is a misconception to envision a sizable, fixed segment of the population with permanent resistance to ESA – resistance fluctuates frequently. The implications of these findings for prescription of ESAs and of hypoxia-inducible factor-prolyl hydroxylase inhibitors are discussed.

Activation of transcription factor HIF inhibits IL-1β-induced NO production in primary cultured rat hepatocytes

Roxadustat and other hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) have recently been approved for the treatment of chronic renal anemia. In macrophages and monocytes, the activation of HIF-1 by pro-inflammatory cytokines induces iNOS expression and activity through the NF-κB pathway to produce nitric oxide (NO), which causes liver injury when excessively produced. Few studies have reported a relationship between HIF activity and iNOS induction in hepatocytes. We investigated the effect of drug- and hypoxia-induced HIF activations on NO production in primary cultured rat hepatocytes. Roxadustat treatment and hypoxic conditions activated HIF. Contrary to expectations, HIF–PHI treatment and hypoxia inhibited IL-1β-induced NO production. RNA-Seq analysis of mRNA expression in rat hepatocytes showed that roxadustat treatment decreased the expression of genes related to inflammation, and genes in the NF-κB signaling pathway were induced by IL-1β. Moreover, roxadustat suppressed IL-1β-activated signaling pathways in an HIF-dependent manner. GalN/LPS-treated rats were used as in vivo models of hepatic injury, and roxadustat treatment showed a tendency to suppress the death of rats. Therefore, exogenous HIF-1 activation, including HIF–PHI and hypoxia exposures, suppressed IL-1β-induced iNOS mRNA expression and subsequent NO production in hepatocytes, by suppressing the NF-κB signaling pathway. Roxadustat treatment suppresses the expression of pro-inflammatory genes by activating HIF, and thus may exhibit hepatoprotective effects.