Impact of HIF prolyl hydroxylase inhibitors in heart failure patients with renal anemia.

OBJECTIVE: Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors are a new class of anti-anemia agents. We retrospectively evaluated the safety and efficacy of HIF-PH inhibitors in patients with heart failure (HF) complicated by anemia associated with chronic kidney disase. HIF-PH inhibitor treatment was initiated in 32 patients with chronic HF complicated by renal anemia and were followed up for 3 months. RESULTS: Hematocrit and hemoglobin levels markedly improved 3 months after HIF-PH inhibitor treatment. However, levels of NT-proBNP, which is an indicator of HF, did not decrease considerably. Based on the rate of change in NT-proBNP, we divided the patients into "responder" and "non-responder" groups. The results showed that considerably more patients had a ferritin level of less than 100 ng/mL in the non-responder group at baseline. There were substantially more patients with TSAT of less than 20% in the non-responder group at 1 month after HIF-PH inhibitor treatment. The cut-off values to maximize the predictive power of ferritin level at baseline and TSAT value at 1 month after treatment were 41.8 ng/ml and 20.75. HIF-PH inhibitor treatment can be expected to be effective for improving both anemia and HF if ferritin≥41.8 ng/ml at baseline or TSAT≥20.75 at 1 month after treatment.

Prolyl hydroxylase domain inhibitor is an effective pre-hospital pharmaceutical intervention for trauma and hemorrhagic shock.

Pre-hospital potentially preventable trauma related deaths are mainly due to hypoperfusion-induced tissue hypoxia leading to irreversible organ dysfunction at or near the point of injury or during transportation prior to receiving definitive therapy. The prolyl hydroxylase domain (PHD) is an oxygen sensor that regulates tissue adaptation to hypoxia by stabilizing hypoxia inducible factor (HIF). The benefit of PHD inhibitors (PHDi) in the treatment of anemia and lactatemia arises from HIF stabilization, which stimulates endogenous production of erythropoietin and activates lactate recycling through gluconeogenesis. The results of this study provide insight into the therapeutic roles of MK-8617, a pan-inhibitor of PHD-1, 2, and 3, in the mitigation of lactatemia in anesthetized rats with polytrauma and hemorrhagic shock. Additionally, in an anesthetized rat model of lethal decompensated hemorrhagic shock, acute administration of MK-8617 significantly improves one-hour survival and maintains survival at least until 4 h following limited resuscitation with whole blood (20% EBV) at one hour after hemorrhage. This study suggests that pharmaceutical interventions to inhibit prolyl hydroxylase activity can be used as a potential pre-hospital countermeasure for trauma and hemorrhage at or near the point of injury.

Zinc Supplementation Enhances the Hematopoietic Activity of Erythropoiesis-Stimulating Agents but Not Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitors.

Since zinc is involved in many aspects of the hematopoietic process, zinc supplementation can reduce erythropoiesis-stimulating agents (ESAs) in patients undergoing hemodialysis. However, it remains unclear whether hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) have similar reduction effects. HIF-PHI stabilizes HIF, which promotes hematopoiesis, although HIF-1α levels are downregulated by zinc. This study aimed to investigate the effect of zinc supplementation on the hematopoietic effect of HIF-PHI in patients undergoing hemodialysis. Thirty patients undergoing maintenance hemodialysis who underwent periods of treatment with roxadustat or darbepoetin alfa during the past 3 years were retrospectively observed. Participants who underwent periods with and without zinc supplementation were selected, with nine treated with darbepoetin alfa and nine treated with roxadustat. Similarly to the ESA responsiveness index (ERI), the hematopoietic effect of zinc supplementation was determined by the HIF-PHI responsiveness index (HRI), which was calculated by dividing the HIF-PHI dose (mg/week) by the patient's dry weight (kg) and hemoglobin level (g/L). Zinc supplementation significantly increased ERI (p < 0.05), but no significant change was observed (p = 0.931) in HRI. Although zinc supplementation did not significantly affect HRI, adequate zinc supplementation is required to alleviate concerns such as vascular calcification and increased serum copper during the use of HIF-PHI.

Efficacy of Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor on Clinical Parameters in Patients with Heart Failure.

Background and Objectives: Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors have been approved as an oral drug for treating anemia in chronic kidney disease (CKD). However, the clinical effect of HIF-PH inhibitors in patients with heart failure (HF) is unclear. Thus, this study investigated the effect of HIF-PH inhibitors in patients with HF and CKD. Materials and Methods: Thirteen patients with HF complicated by renal anemia who were started on vadadustat were enrolled. Clinical parameters were compared before and 1 month after vadadustat was started. Results: The mean left ventricular ejection fraction was 49.8 ± 13.9%, and the mean estimated glomerular filtration rate was 29.4 ± 10.6 mL/min/1.73 m2. The hemoglobin level was significantly increased (9.7 ± 1.3 mg/dL vs. 11.3 ± 1.3 mg/dL, p < 0.001), and the N-terminal prohormone of B-type natriuretic peptide was significantly decreased after the introduction of vadadustat [4357 (2651-15182) pg/mL vs. 2367 (1719-9347) pg/mL, p = 0.002]. Furthermore, the number of patients with New York Heart Association functional class ≥ 3 was also decreased after the introduction of vadadustat [8 (61.5%) vs. 1 (7.7%), p = 0.008]. No thromboembolic adverse events or new tumors were observed in any patient during the study period. Conclusions: The introduction of vadadustat in patients with HF complicated by renal anemia led to improvements in anemia and symptoms of HF.

HIF-PHD inhibitor desidustat ameliorates iron deficiency anemia.

Iron deficiency anemia is caused by many pathological conditions like chronic kidney disease (CKD), inflammation, malnutrition and gastrointestinal abnormality. Current treatments that are erythropoiesis stimulating agents (ESAs) and iron supplementation are inadequate and often lead to tolerance and/or toxicity. Desidustat, a prolyl hydroxylase (PHD) inhibitor, is clinically used for the treatment of anemia with CKD. In this study, we investigated the effect of desidustat on iron deficiency anemia (IDA). IDA was induced in C57BL6/J mice by iron deficient diet feeding. These mice were then treated with desidustat (15 mg/kg, PO) and FeSO4 (20 mg/kg) for five weeks and effect of the treatment on hematology, iron homeostasis, and bone marrow histology was observed. Effect of desidustat on iron metabolism in inflammation (LPS)-induced iron deficiency was also assessed. Both, Desidustat and FeSO4, increased MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), hemoglobin, and HCT (hematocrit) in blood and increased iron in serum, liver, and spleen. Desidustat increased MCHC (mean corpuscular hemoglobin concentration) while FeSO4 treatment did not alter it. FeSO4 treatment significantly increased iron deposition in liver, and spleen, while desidustat increased iron in circulation and demonstrated efficient iron utilization. Desidustat increased iron absorption, serum iron and decreased hepcidin without altering tissue iron, while FeSO4 increased serum and tissue iron by increasing hepcidin in LPS-induced iron deficiency. Desidustat increased erythroid population, especially iron-dependent polychromatic normoblasts and orthochromatic normoblasts, while FeSO4 did not improve cell architecture. PHD inhibition by desidustat improved iron utilization in iron deficiency anemia, by efficient erythropoiesis.

Discovery of Novel and Potent Prolyl Hydroxylase Domain-Containing Protein (PHD) Inhibitors for The Treatment of Anemia.

Stabilization of hypoxia-inducible factor (HIF) by inhibiting prolyl hydroxylase domain enzymes (PHDs) represents a breakthrough in treating anemia associated with chronic kidney disease. Here, we identified a novel scaffold for noncarboxylic PHD inhibitors by utilizing structure-based drug design (SBDD) and generative models. Iterative optimization of potency and solubility resulted in compound 15 which potently inhibits PHD thus stabilizing HIF-α in vitro. X-ray cocrystal structure confirmed the binding model was distinct from previously reported carboxylic acid PHD inhibitors by pushing away the R383 and Y303 residues resulting in a larger inner subpocket. Furthermore, compound 15 demonstrated a favorable in vitro/in vivo absorption, distribution, metabolism, and excretion (ADME) profile, low drug-drug interaction risk, and clean early safety profiling. Functionally, oral administration of compound 15 at 10 mg/kg every day (QD) mitigated anemia in a 5/6 nephrectomy rat disease model.

Use of molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, in chronic kidney disease-associated anemia in cats.

BACKGROUND: Erythropoietic effects of molidustat, a hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor, were previously demonstrated in healthy cats. OBJECTIVE: To evaluate the safety and erythropoietic effects of daily PO administration of molidustat in anemic cats with chronic kidney disease (CKD). ANIMALS: Twenty-one client-owned CKD cats (4-17 years old) with anemia. METHODS: Multicenter field study; randomized, masked, and placebo-controlled. Cats were treated PO once daily for 28 days with suspensions of control product (CP; n = 6) or 5 mg/kg of molidustat (n = 15). Hematocrit (HCT) was evaluated at weekly intervals. Individual cat treatment success was defined as a ≥4% point increase in HCT compared to baseline. RESULTS: Control group mean HCT remained low throughout the study (20.1%-23.4%). Mean HCT of molidustat-treated cats increased weekly, and a significant increase compared to baseline (23.6%) was first observed on Day 21 (27.3%; P < .001; 95% confidence interval [CI], 1.69-5.67). Compared to CP group, mean HCT was significantly higher on Day 21 (27.3% vs 20.1%; P < .001; 95% CI, 2.91-10.75) but not significantly higher on Day 28 (27.8% vs 23.4%; P = .06; 95% CI, -0.23 to 9.88). The number of individual treatment successes on Day 28 was higher among remaining molidustat-treated cats (7/14) compared to remaining control cats (1/5), but there was no significant difference between groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Daily PO molidustat administration may stimulate a clinically relevant erythropoietic response in anemic cats with CKD. This HIF-PH inhibitor may be an alternative for managing anemia in cats compared to recombinant EPO treatment.

[New Therapeutic Strategies in the Treatment of CKD Anemia: Hypoxia-Induced Factor Prolyl-Hydroxylase Inhibitors].

The link between chronic renal failure and anemia has been known for more than 180 years, negatively impacting the quality of life, cardiovascular risk, mortality, and morbidity of patients with chronic kidney disease (CKD). Traditionally, the management of anemia in CKD has been based on the use of replacement martial therapy, vitamin therapy, and the use of erythropoiesis-stimulating agents (ESAs). In recent years, alongside these consolidated therapies, new molecules known as hypoxia-induced factor prolyl-hydroxylase inhibitors (HIF-PHIs) have appeared. The mechanism of action is expressed through an increased transcriptional activity of the HIF gene with increased erythropoietin production. The drugs currently produced are roxadustat, daprodustat, vadadustat, molidustat, desidustat, and enarodustat; among these only roxadustat is currently approved and usable in Italy. The possibility of oral intake, pleiotropic activity on martial and lipidic metabolism, and the non-inferiority compared to erythropoietins make these drugs a valid alternative to the treatment of anemia associated with chronic kidney disease in the nephrologist practice.

[Hypoxia-inducible factor-prolyl hydroxylase inhibitors: the "alternative" for EPO?] / Hypoxie-induceerbare-factor-prolylhydroxylaseremmers.

Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHI) are a new drug class for the treatment of renal anemia. HIF-PHI increase the expression of genes such as erythropoietin and genes involved in iron homeostasis. HIF-PHI were found to be superior to placebo in increasing hemoglobin levels and non-inferior to erythropoiesis stimulating agents (ESA). Furthermore, HIF-PHI appeared to positively influence iron parameters and also appeared to be effective in patients with elevated inflammatory values. The cardiovascular safety of HIF-PHI was found to be similar to ESA in most studies. However, a stronger risk of deep vein thrombosis and thrombosis of the shunt was found with treatment of HIF-PHI compared to ESA. HIF-PHI can be considered as an alternative to ESA, with the positive effect on iron homeostasis, the oral administration and the potential possibility to treat patients with ESA hyporesponsiveness as additional benefits, although effectiveness in this subgroup has yet to be demonstrated.

Changes in Metabolomic Profiles Induced by Switching from an Erythropoiesis-Stimulating Agent to a Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor in Hemodialysis Patients: A Pilot Study.

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are a new class of medications for managing renal anemia in patients with chronic kidney disease (CKD). In addition to their erythropoietic activity, HIF-PHIs exhibit multifaceted effects on iron and glucose metabolism, mitochondrial metabolism, and angiogenesis through the regulation of a wide range of HIF-responsive gene expressions. However, the systemic biological effects of HIF-PHIs in CKD patients have not been fully explored. In this prospective, single-center study, we comprehensively investigated changes in plasma metabolomic profiles following the switch from an erythropoiesis-stimulating agent (ESA) to an HIF-PHI, daprodustat, in 10 maintenance hemodialysis patients. Plasma metabolites were measured before and three months after the switch from an ESA to an HIF-PHI. Among 106 individual markers detected in plasma, significant changes were found in four compounds (erythrulose, n-butyrylglycine, threonine, and leucine), and notable but non-significant changes were found in another five compounds (inositol, phosphoric acid, lyxose, arabinose, and hydroxylamine). Pathway analysis indicated decreased levels of plasma metabolites, particularly those involved in phosphatidylinositol signaling, ascorbate and aldarate metabolism, and inositol phosphate metabolism. Our results provide detailed insights into the systemic biological effects of HIF-PHIs in hemodialysis patients and are expected to contribute to an evaluation of the potential side effects that may result from long-term use of this class of drugs.

Association of Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors with Cardiovascular Events and Death in Dialysis Patients: A Systematic Review and Meta-Analysis.

BACKGROUND: Anemia is a common finding among patients with advanced chronic kidney disease, especially those on dialysis. The recent introduction of hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) has raised some concerns about the cardiovascular and thrombotic complications of this class of drugs. OBJECTIVES: This meta-analysis aimed to assess the safety of HIF-PHIs in patients with end-stage kidney disease (ESKD) versus standard therapy with erythropoiesis-stimulating agents (ESAs). METHODS: Databases were searched on April 2022. Studies that reported incidence of all-cause mortality; major cardiovascular adverse events (MACEs); myocardial infarction (MI); stroke and thrombotic events in the use of HIF-PHIs or ESA on ESKD patients in hemodialysis or peritoneal dialysis were evaluated. Data were extracted from published reports, and quality assessment was performed per Cochrane recommendations. RESULTS: 12,821 patients from ten randomized controlled trials were included in this study. Most patients (83%) were on hemodialysis. 6,461 (50.3%) were using HIF-PHIs, and 6,360 (49.6%) were in the ESA group. The pooled estimated incidence of all-cause mortality was 769 in the HIF-PHIs group (relative-risk ratios (RR): 1.04; confidence interval (CI): 0.95-1.14; p = 0.52; I2 = 0%). There was no difference in the groups regarding the outcomes of MACE in the analysis of the three studies that reported this outcome (RR: 0.95; CI: 0.87-1.04; p = 0.69; I2 = 0%). In addition, there was no statistical difference among the outcomes of MI, stroke, or thrombotic events. CONCLUSIONS: Among patients with ESKD on dialysis, the use of HIF-PHIs was non-inferior regarding the safety outcomes when compared to standard of care therapy.

Preferred Conformation-Guided Discovery of Potent and Orally Active HIF Prolyl Hydroxylase 2 Inhibitors for the Treatment of Anemia.

In this work, we discovered a novel series of prolyl hydroxylase 2 (PHD2) inhibitors with improved metabolic properties based on a preferred conformation-guided drug design strategy. Piperidinyl-containing linkers with preferred metabolic stability were designed to match the dihedral angle of the desired docking conformation in the PHD2 binding site with the lowest energy conformation. Based on the piperidinyl-containing linkers, a series of PHD2 inhibitors with high PHD2 affinity and favorable druggability were obtained. Remarkably, compound 22, with an IC50 of 22.53 nM toward PHD2, significantly stabilized hypoxia-inducible factor α (HIF-α) and upregulated the expression of erythropoietin (EPO). Furthermore, oral administration of 22 dose-dependently stimulated erythropoiesis in vivo. Preliminary preclinical studies showed that 22 has good pharmacokinetic properties and an excellent safety profile, even at 10 times the efficacious dose (200 mg/kg). Taken together, these results indicate that 22 is a promising candidate for anemia treatment.

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.

Hypoxia-inducible factor prolyl hydroxylase inhibitors suppressed thymic stromal lymphopoietin production and allergic responses in a mouse air-pouch-type ovalbumin sensitization model.

Atopic dermatitis (AD) is an allergic skin disease, triggered by excessive type 2 immune reactions. Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine that induces type 2 immune response through dendritic cell activation. Therefore, TSLP inhibitors may serve as novel antiallergic drugs. Hypoxia-inducible factor (HIF) activation in the epithelia contributes to several homeostatic phenomena, such as re-epithelialization. However, the effects of HIF activation on TSLP production and immune activation in the skin remain unclear. In this study, we found that selective HIF prolyl hydroxylase inhibitors (PHD inhibitors), which induce HIF activation, suppressed TSLP production in a mouse ovalbumin (OVA) sensitization model. PHD inhibitors also suppressed the production of tumor necrosis factor-alpha (TNF-α), which is a major inducer of TSLP production, in this mouse model and in a macrophage cell line. Consistent with these findings, PHD inhibitors suppressed OVA-specific IgE levels in the serum and OVA-induced allergic responses. Furthermore, we found a direct suppressive effect on TSLP expression in a human keratinocyte cell line mediated by HIF activation. Taken together, our findings suggest that PHD inhibitors exert antiallergic effects by suppressing TSLP production. Controlling the HIF activation system has therapeutic potential in AD.

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 network meta-analysis of the efficacy of hypoxia-inducible factor prolyl-hydroxylase inhibitors in dialysis chronic kidney disease.

BACKGROUND: Five types of HIF-PHIs have been authorized for anemia treatment in CKD patients in China and Japan. These are enarodustat, roxadustat, daprodustat, vadadustat, and molidustat. How effectively they compare to ESAs about clinical results in CKD-DD patients is uncertain. This study examined the RCT evidence about the benefits and risks of HIF-PHIs and ESAs in dialysis CKD patients. METHODS: We conducted an extensive investigation and network meta-analysis of RCTs. In these RCTs, patients with CKD-DD received one of five different HIF-PHI or ESAs, a placebo, and no medical intervention. Outcomes included hemoglobin, iron parameters, and adverse events, and there were four weeks of follow-up at least. A frequentist framework for multivariate random effects meta-analyzed the results. The effect sizes of categorical variables were displayed as odds ratios. Mean differences were employed for computing continuous outcomes with common units; otherwise, standardized mean differences were applied. The Cochrane tool evaluated the bias risk in RCTs. RESULTS: 26 RCTs with 14945 patients were qualified for inclusion. Compared to the placebo, HIF-PHIs and ESAs dramatically boosted hemoglobin without affecting serum iron. Roxadustat performed better hemoglobin levels than ESAs (MD 0.32, 95% CI 0.10 to 0.53) and daprodustat (0.46, 0.09 to 0.84). Roxadustat (91.8%) was the top hemoglobin treatment among all medical interventions, as determined by the SUCRA ranking. However, roxadustat caused more thrombosis and hypertension than ESAs (1.61, 1.22 to 2.12) and vadadustat (1.36, 1.01 to 1.82). The lowest rates of hypertension and thrombosis were seen in molidustat (80.7%) and ESAs (88.5%). Compared with a placebo, ESAs and HIF-PHIs all affected TSAT levels. Except for molidustat, the other four HIF-PHIs impact different iron parameters. Regarding ferritin reduction, roxadustat (90.9%) and daprodustat (60.9%) came out on top. Enarodustat (80.9%) and roxadustat (74%) placed best and second in lowering hepcidin levels. The former two medicines for TIBC improvement were vadadustat (98.7%) and enarodustat (80.9%). CONCLUSION: The most effective treatment for hemoglobin correction is roxadustat. The superior efficacy of reducing hepcidin makes roxadustat and enarodustat appropriate for patients with inflammation. However, the increased risk of hypertension and thrombosis associated with roxadustat should be noted. In patients at risk for hypertension and thrombosis, molidustat and ESAs may be preferable options. When administering roxadustat and daprodustat, clinicians should check ferritin to assess iron storage. Lower TSAT in patients receiving HIF-PHIs and ESAs treatment suggests intravenous iron supplements are needed.

Therapeutic Potential of the Prolyl Hydroxylase Inhibitor Roxadustat in a Mouse Hindlimb Lymphedema Model.

Background: Lymphedema is an intractable disease with no curative treatment available. Conservative treatment is the mainstay, and new drug treatment options are strongly needed. The purpose of this study was to investigate the effect of roxadustat, a prolyl-4-hydroxylase inhibitor, on lymphangiogenesis and its therapeutic effect on lymphedema in a radiation-free mouse hindlimb lymphedema model. Methods and Results: Male C57BL/6N mice (8-10 weeks old) were used for the lymphedema model. Mice were randomized to an experimental group receiving roxadustat or a control group. The circumferential ratio of the hindlimbs was evaluated, and lymphatic flow of the hindlimbs was compared by fluorescent lymphography up to 28 days postoperatively. The roxadustat group showed an early improvement in hindlimb circumference and stasis of lymphatic flow. The number and area of lymphatic vessels on postoperative day 7 were significantly larger and smaller, respectively, in the roxadustat group compared with the control group. Skin thickness and macrophage infiltration on postoperative day 7 were significantly reduced in the roxadustat group compared with the control group. The relative mRNA expression of hypoxia-inducible factor-1α (Hif-1α), vascular endothelial growth factor receptor-3 (VEGFR-3), vascular endothelial growth factor-C (VEGF-C), and Prospero homeobox 1 (Prox1) on postoperative day 4 was significantly higher in the roxadustat group compared with the control group. Conclusions: Roxadustat demonstrated a therapeutic effect in a murine model of hindlimb lymphedema through promotion of lymphangiogenesis through the activation of HIF-1α, VEGF-C, VEGFR-3, and Prox1, suggesting the potential of roxadustat as a therapeutic option in lymphedema.

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

PURPOSE: 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. METHODS: 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. RESULTS: We identified 7 trials comprising of 8228 patients (mean age 66.5 ± 13.2 years, 42% were females, 53% used iron replacement) with a mean follow-up of 52 weeks. 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. CONCLUSION: HIF-PHI might represent a safe, and convenient alternative to ESA in non-dialysis dependent CKD patients with anemia.

Regulation of Erythropoiesis by the Hypoxia-Inducible Factor Pathway: Effects of Genetic and Pharmacological Perturbations.

Red blood cells transport O2 from the lungs to body tissues. Hypoxia stimulates kidney cells to secrete erythropoietin (EPO), which increases red cell mass. Hypoxia-inducible factors (HIFs) mediate EPO gene transcriptional activation. HIF-α subunits are subject to O2-dependent prolyl hydroxylation and then bound by the von Hippel-Lindau protein (VHL), which triggers their ubiquitination and proteasomal degradation. Mutations in the genes encoding EPO, EPO receptor, HIF-2α, prolyl hydroxylase domain protein 2 (PHD2), or VHL cause familial erythrocytosis. In addition to O2, α-ketoglutarate is a substrate for PHD2, and analogs of α-ketoglutarate inhibit hydroxylase activity. In phase III clinical trials evaluating the treatment of anemia in chronic kidney disease, HIF prolyl hydroxylase inhibitors were as efficacious as darbepoetin alfa in stimulating erythropoiesis. However, safety concerns have arisen that are focused on thromboembolism, which is also a phenotypic manifestation of VHL or HIF-2α mutation, suggesting that these events are on-target effects of HIF prolyl hydroxylase inhibitors.

The current therapeutic approach for anaemia after kidney transplant.

PURPOSE OF REVIEW: Anaemia after kidney transplantation is a common finding with no uniform management guideline. Most approaches are derived from the chronic kidney disease (CKD) population. Recent advances for the treatment of anaemia in patients with CKD/End stage renal disease include hypoxia-inducible factor-prolyl hydroxylase inhibitor (HIF-PHi), a novel class of oral erythropoietin-stimulating agents (ESAs). We present relevant studies of HIF-PHi in the transplant population and its implications on the management of posttransplant anaemia. RECENT FINDINGS: Data on HIF-PHi use in the kidney transplant population are promising. Limited data demonstrate a significant increase in haemoglobin, with a comparable safety profile to epoetin. Reported adverse effects include overcorrection and low iron stores. SUMMARY: Current therapeutic approaches to anaemia in the kidney transplant population is mostly derived from the CKD population. More studies are needed on HIF-Phi, a novel class of ESAs that has thus far demonstrated promise in the kidney transplant population.