Treatment Of Renal Anemia Research Articles

Chemistry, Analysis, and Biological Aspects of Daprodustat, A New Hypoxia Inducible Factor Prolyl Hydroxylase Inhibitor: A Comprehensive Review.

The National Health and Nutrition Examination Survey (NHANES) carried out a survey between 2007-10 and found that as compared to the general population, the prevalence of anemia in chronic kidney disease (CKD) patients was twice high. Daprodustat is an investigational novel drug for the treatment of renal anemia. The objective of this study is to provide a comprehensive review of chemistry, synthesis, pharmacology, pharmacokinetic, and bioanalytical methods for the analysis of Daprodustat. To improve understanding, a review was carried out by creating a database of relevant prior research from electronic sources such as ScienceDirect and PubMed. The methodology is shown in the flowchart of the literature selection process. The drug was approved in 2020 for therapeutic purposes in Japan. It is a novel drug approved for the treatment of anemia in chronic kidney disease for oral administration. It is intended for adults who have undergone dialysis for a minimum of four months and are experiencing anemia as a result of chronic kidney disease. This review examines therapeutic, pharmacological, and analytical aspects related to the novel drug Daprodustat.

Progress in the Study of the Therapeutic Effects of Roxarestat

Hypoxia-inducible factor has a wide range of roles in the human body and is involved in pathophysiological processes including erythropoietin production, iron uptake metabolism and energy metabolism. Roxarestat is a small molecule inhibitor of hypoxia-inducible factor prolyl hydroxylase, which can stabilize the level of hypoxia-inducible factor to participate in systemic biological functions. Roxarestat is widely used in the treatment of renal anemia. With the deepening of research, it is found that roxarestat has therapeutic potential for renal fibrosis, cardiovascular disease, retinopathy, etc. This article summarizes the current status of roxarestat in the treatment of renal anemia, and its therapeutic effects on other therapies.

Roxadustat has risks of reversible central hypothyroidism in patients undergoing hemodialysis: a single-center retrospective cohort study

Roxadustat, a hypoxia-inducible factor-prolyl hydroxylase inhibitor, has proven efficacy in the treatment of renal anemia; however, evidence indicates that it may cause central hypothyroidism. The prevalence and reversibility of roxadustat-induced central hypothyroidism in patients undergoing hemodialysis remain unclear. Here, we retrospectively analyzed thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) levels in 51 patients (mean age: 72.3 ± 10.7 years; 58.8% male) undergoing hemodialysis before, during, and after halting roxadustat treatment. TSH levels were significantly decreased from a median of 2.46 (interquartile range:1.60–4.51) mU/L before roxadustat treatment to 1.36 (0.72–2.41) mU/L during treatment (p < 0.001), and improved to 2.56 (1.78–4.63) mU/L after halting roxadustat (p < 0.001). Similarly, FT4 levels decreased from 1.11 (0.97–1.24) ng/dL before roxadustat treatment to 0.92 (0.71–1.03) ng/dL during treatment (p < 0.001) and improved to 1.05 (0.93–1.17) ng/dL after halting roxadustat (p < 0.001). FT3 levels were 2.04 (1.78–2.31) pg/mL before starting roxadustat, 1.97 (1.69–2.27) pg/mL during treatment, and 1.90 (1.63–2.18) pg/mL after halting roxadustat, with no significant difference between each group. Moreover, 2.0% of patients exhibited extremely low TSH levels (≤0.1 mU/L) and low TSH levels (>0.1 mU/L to <0.4 mU/L) before starting roxadustat and that percentage increased to 5.9% and 7.8%, respectively, during treatment. After roxadustat cessation, extremely low or low TSH levels recovered in all patients. Taken together, the results indicate that roxadustat can cause reversible central hypothyroidism in patients undergoing hemodialysis.

Optimizing the dosing regimen of roxadustat in kidney transplant recipients with early post-transplant anemia

IntroductionRoxadustat, an oral inhibitor of hypoxia-inducible factor prolyl hydroxylase domain enzymes, has been approved for the treatment of renal anemia. However, there is a lack of study on its pharmacokinetics in kidney transplant recipients (KTRs) with early posttransplant anemia (PTA). Therefore, the aim of this study is to elucidate the pharmacokinetic characteristics of roxadustat in KTRs with early PTA and optimize the dosing regimen. MethodsA population pharmacokinetic (PopPK) analysis was performed based on 72-hour full concentration-time profiles collected from 52 Chinese KTRs. Covariates influencing exposure were assessed using stepwise covariate modelling. Monte Carlo simulations were conducted to recommend the dosing regimen for patients with different levels of covariates. ResultsPopPK analysis showed that the concentration-time data can be fully described by a two-compartment model. Body weight (BW) and direct bilirubin (DBIL) levels significant affected the apparent clearance of roxadustat. Based on the established model and the estimated exposures of roxadustat by Monte Carlo simulations, a recommended dosing regimen for KTRs with early PTA at varying BW and DBIL levels were developed. Roxadustat at 100 mg three times weekly were suitable for the majority of KTRs with a DBIL level around 3 μmol/L and BW between 50 and 75 kg. The required dose may need to be increased with higher BW and lower DBIL levels, while decreased with lower BW and higher DBIL levels. ConclusionsIt was the first PopPK analysis of roxadustat in KTRs with early PTA, which provide a research basis for optimizing the dosing regimen.

The clinical efficacy of combined ESA and Roxadustat treatment for renal anemia in hemodialysis patients with secondary hyperparathyroidism: A case series.

Pharmacological mechanism of Roxadustat in the treatment of renal anemia. To investigate the efficacy and safety of combined Roxadustat and erythropoiesis stimulator (ESA) treatment of renal anemia in hemodialysis patients with secondary hyperparathyroidism. A retrospective analysis was conducted on hemodialysis patients with renal anemia and secondary hyperparathyroidism treated with ESAs alone, who were admitted to our hospital from March 2022 to December 2022. The patients were treated with Roxadustat combined with ESAs for 3 months, during which oral iron supplementation was given, and the changes in Hb levels and laboratory-related indicators before and after the combined treatment were analyzed. The results showed that a total of 13 patients received combination therapy, with a significant increase in Hb compared to ESAs alone (t = -3.955, P = .002). The Hb qualification rate was 38.46%, and the ∆Hb response rate was 76.92%. The parathyroid hormone significantly decreased with a statistically significant difference (Z = -2.062b, P = .039). Hemoglobin (RBC), total iron binding capacity, and serum ferritin (male) were significantly increased compared to ESAs alone. Total cholesterol and low-density lipoprotein were significantly lower than ESAs alone. The differences in the changes in the above indicators were statistically significant (P < .05). There was no statistically significant difference in changes in other laboratory-related indicators (P > .05). No adverse reactions were observed during the combined treatment of 13 patients. The combination of Roxadustat and ESAs can effectively improve renal anemia in hemodialysis patients with secondary hyperparathyroidism, as well as improve indicators of hyperparathyroidism and blood lipid levels with high levels of safety. This combined treatment thus provides a new and safe treatment method for these patients.

Discovery of DS-1093a: An oral hypoxia-inducible factor prolyl hydroxylase inhibitor for the treatment of renal anemia

Inhibition of the hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) represents a promising strategy for discovering next-generation treatments for renal anemia. We discovered DS44470011 in our previous study, which showed potent in vitro activity and in vivo efficacy based on HIF-PHD inhibition. However, DS44470011 was also found to exert genotoxic effects. By converting the biphenyl structure, which is suspected to be the cause of this genotoxicity, to a 1-phenylpiperidine structure, we were able to avoid genotoxicity and further improve the in vitro activity and in vivo efficacy. Furthermore, through the optimization of pyrimidine derivatives, we discovered DS-1093a, which has a wide safety margin with potent in vitro activity and an optimal pharmacokinetic profile. DS-1093a achieved an increase in hemoglobin levels in an adenine-induced rat model of chronic kidney disease after its continuous administration for 4 days.

Renal anemia: from relative insufficiency of EPO to imbalance of erythropoiesis and eryptosis.

Chronic kidney disease has emerged as a major health issue both in China and worldwide. Renal anemia frequently occurs in patients with chronic kidney disease, and its severity and incidence rate increase as the disease progresses. Over the last 30 years, the administration of exogenous EPO and EPO stimulants has been employed to alleviate renal anemia, suggesting that a relative deficiency in EPO may be a primary cause. However, this approach has overshadowed other contributing factors, particularly eryptosis, which results from the reduced lifespan of red blood cells. Numerous studies reveal that there are nephrogenic and extrarenal EPO secretion indicating that an absolute deficiency of EPO is not always present in patients. Therefore, this paper speculates that renal anemia may arise when EPO-driven erythropoiesis fails to adequately compensate for aggravating eryptosis. Other factors including iron metabolism disorder, uremic toxin accumulation, inflammatory state, oxidative stress, and secondary hyperparathyroidism affect EPO reactivity bone marrow hematopoiesis and eryptosis, leading to an imbalance between red blood cell production and destruction, and cause anemia ultimately. More further studies on the pathogenesis and treatment of renal anemia would be expected to provide evidence to support our opinion.

The Comparison between Vadadustat and Daprodustat Regarding Dose, Cost, and Safety of Treatment for Renal Anemia in Non-dialysis Patients with Chronic Kidney Diseases.

Objective We retrospectively compared the dose, cost, and safety of vadadustat and daprodustat for the treatment of renal anemia in patients with chronic kidney diseases who were not undergoing dialysis. Methods The primary outcome of this study was the change in dose and cost from the initiation of vadadustat and daprodustat treatment. The secondary outcome was the drug safety. Patients We treated 30 patients each with the hypoxia-inducible factor prolyl-hydroxylase inhibitors (HIF-PHIs) daprodustat and vadadustat. The hemoglobin (Hb) concentration was targeted at 11-13 g/dL, and transferrin saturation was maintained at ≥20%, as per the 2018 Japanese guidelines for the diagnosis and treatment of chronic kidney disease. Results Hb levels increased from 10.7 to 11.5 g/dL after the first month of daprodustat administration, whereas those for vadadustat patients remained relatively stable, going from 10.7 to 10.6 g/dL. After six months, the Hb level reached 12.1 g/dL and 11.3 g/dL for daprodustat and vadadustat, respectively. The dosage of vadadustat was significantly increased by 46% and 70% after 3 and 12 months, respectively, compared with the initial doses, whereas that of daprodustat did not change substantially. The average cost of vadadustat also increased in the first 3 months and remained over 500 yen/day after 3 months, while that of daprodustat showed little change from the initial cost of 360 yen/day. Conclusion These results suggest that heterogeneity exists in the drug potency and dosage required for treatment between daprodustat and vadadustat. Serious adverse events [death, cardiovascular disease, end stage renal disease (ESRD), and malignancy] occurred in more than 20% of participants with both HIF-PHIs. Further studies are required to confirm the safety of HIF-PHIs.

HIF-ɑ: New Target For Treatment of Renal Anemia. Molecular Aspects and Activation of Pathway HREs

Roxadustat, recently approved, is a hypoxia-inducible factor prolyl hydroxylase inhibitor that has demonstrated favorable safety and efficacy in the treatment of renal anemia. This article reviews main features and possible effects by activation of pathway sequences HREs.

Activation of the hypoxia-inducible factor pathway by roxadustat improves glucose metabolism in human primary myotubes from men

Aims/hypothesisHypoxia-inducible factor prolyl 4-hydroxylase (HIF-P4H) enzymes regulate adaptive cellular responses to low oxygen concentrations. Inhibition of HIF-P4Hs leads to stabilisation of hypoxia-inducible factors (HIFs) and activation of the HIF pathway affecting multiple biological processes to rescue cells from hypoxia. As evidence from animal models suggests that HIF-P4H inhibitors could be used to treat metabolic disorders associated with insulin resistance, we examined whether roxadustat, an HIF-P4H inhibitor approved for the treatment of renal anaemia, would have an effect on glucose metabolism in primary human myotubes.MethodsPrimary skeletal muscle cell cultures, established from biopsies of vastus lateralis muscle from men with normal glucose tolerance (NGT) (n=5) or type 2 diabetes (n=8), were treated with roxadustat. Induction of HIF target gene expression was detected with quantitative real-time PCR. Glucose uptake and glycogen synthesis were investigated with radioactive tracers. Glycolysis and mitochondrial respiration rates were measured with a Seahorse analyser.ResultsExposure to roxadustat stabilised nuclear HIF1α protein expression in human myotubes. Treatment with roxadustat led to induction of HIF target gene mRNAs for GLUT1 (also known as SLC2A1), HK2, MCT4 (also known as SLC16A4) and HIF-P4H-2 (also known as PHD2 or EGLN1) in myotubes from donors with NGT, with a blunted response in myotubes from donors with type 2 diabetes. mRNAs for LDHA, PDK1 and GBE1 were induced to a similar degree in myotubes from donors with NGT or type 2 diabetes. Exposure of myotubes to roxadustat led to a 1.4-fold increase in glycolytic rate in myotubes from men with NGT (p=0.0370) and a 1.7-fold increase in myotubes from donors with type 2 diabetes (p=0.0044), with no difference between the groups (p=0.1391). Exposure to roxadustat led to a reduction in basal mitochondrial respiration in both groups (p<0.01). Basal glucose uptake rates were similar in myotubes from donors with NGT (20.2 ± 2.7 pmol mg−1 min−1) and type 2 diabetes (25.3 ± 4.4 pmol mg−1 min−1, p=0.4205). Treatment with roxadustat enhanced insulin-stimulated glucose uptake in myotubes from donors with NGT (1.4-fold vs insulin-only condition, p=0.0023). The basal rate of glucose incorporation into glycogen was lower in myotubes from donors with NGT (233 ± 12.4 nmol g−1 h−1) than in myotubes from donors with type 2 diabetes (360 ± 40.3 nmol g−1 h−1, p=0.0344). Insulin increased glycogen synthesis by 1.9-fold (p=0.0025) in myotubes from donors with NGT, whereas roxadustat did not affect their basal or insulin-stimulated glycogen synthesis. Insulin increased glycogen synthesis by 1.7-fold (p=0.0031) in myotubes from donors with type 2 diabetes. While basal glycogen synthesis was unaffected by roxadustat, pretreatment with roxadustat enhanced insulin-stimulated glycogen synthesis in myotubes from donors with type 2 diabetes (p=0.0345).Conclusions/interpretationRoxadustat increases glycolysis and inhibits mitochondrial respiration in primary human myotubes regardless of diabetes status. Roxadustat may also improve insulin action on glycogen synthesis in myotubes from donors with type 2 diabetes.Graphical

#3026 Uncovering the potential of HIF-PH inhibitors to treat renal anemia

Abstract Background and Aims Hypoxia-inducible factor prolyl hydroxylase enzyme inhibitors (HIF-PHis) are a novel class of agents that were developed for the treatment of renal anemia. The agents work by stabilizing the HIF complex and stimulating endogenous erythropoietin production. This research aims to gauge the potential utilization and impact of HIF-PHis based on the perspectives of nephrologists who are based in the EU5. Method Data were collected via an independent online survey of 204 nephrologists based in the EU5 (UK, Germany, Italy, France, and Spain) in November 2023. Results EU5 nephrologists report that most dialysis and CKD non-dialysis patients with renal anemia who are on ESA therapy have an optimal response to treatment; however, a substantial proportion of patients experience a suboptimal response to treatment and up to 13% of patients across dialysis modalities are classified as ESA hypo-responders. Regardless of their geographic location, EU5 nephrologists position HIF-PHis to offer the most value in the CKD non-dialysis patient setting, with a perceived high level of opportunity (80%) for roxadustat to improve renal anemia outcomes among non-dialysis patients. Not surprisingly, the perceived advantages of an oral agent over an injectable medication for the treatment of renal anemia are more substantial for dialysis patients who are receiving home therapies (peritoneal and home hemodialysis) compared to those receiving in-center hemodialysis treatment. EU5 nephrologists also tend to believe that roxadustat represents a high level (64%) of opportunity to improve renal anemia outcomes in dialysis patients, with similar ratings observed for vadadustat (63%) in the same patient population. Specific to the use of HIF-PH inhibitors in the CKD non-dialysis setting, nephrologists are most concerned about patient compliance (51%), followed by safety compared to ESAs in general and as they relate to cardiovascular events (36%). When considering the use of HIF-PH inhibitors in the dialysis setting, nephrologists express similar concerns compared to the non-dialysis setting, with patient compliance (50%) ranked as the top concern, followed by safety compared to ESAs (38%), and the potential for off target effects (33%). Most EU5 nephrologists agree that HIF-PH inhibitors represent a more physiologic way of treating anemia of CKD compared to ESAs (70%) and many would like gain more clinical experience with the class of medications (63%). Current roxadustat treatment rates in dialysis are slowly increasing across the EU5 region, with slightly higher adoption in peritoneal dialysis patients (10%) compared to in-center hemodialysis patients (8%). Meanwhile, their self-reported uptake of roxadustat in CKD non-dialysis patients is also increasing over time, with the largest increase observed in CKD Stage 4 patients (9%). There is little consensus among EU5 nephrologists regarding their expected time to trial vadadustat once it is available, as nearly the same proportion of prescribers project that they will prescribe the agent to their dialysis patients within three months (36%), six months (23%), and within one year (28%). Conclusion With HIF-PHis having more of a physiologic mechanism of action, oral administration, and a similar safety profile compared to ESAs, broader adoption of the novel agents will potentially help address unmet needs and improve patient outcomes in the treatment of renal anemia for both CKD non-dialysis and dialysis patients.

#535 Roxadustat as a treatment of anemia after kidney transplantation

Abstract Background and Aims Roxadustat is a recently approved hypoxia-inducible factor prolyl hydroxylase inhibitor that has demonstrated favourable safety and efficacy in the treatment of renal anaemia. The goal of this study is to analyse the effect of roxadustat on the level of hemoglobin in a group of patient with chronic kidney disease with or without kidney transplantation. Method This is a monocentric study conducted on the patients of Transplant-nephrology department and/or Transplant-nephrology out-patient clinic of University Hospital Martin, Slovakia who have been treated with roxadusat since August 1st, 2022. Results 33 patients were included in the study. The average follow up of treatment with roxadustat was 4.2 months. The following parameters were recorded at the baseline: age, gender, estimated glomerular filtration rate—eGFR (CKD-EPI), treatment with iron and level of iron in serum, level of C-reactive protein, level of hemoglobin, starting dose of Roxadustat. We discovered a significant improvement in the levels of hemoglobin after one month of roxadustat treatment (P &amp;lt; 0.0001) and another significant improvement in follow-up (P ‚0,0373). There was no significant difference in eGFR, CRP or iron levels during follow up, so hemoglobin levels were not affected by inflammation or kidney function. In the next step the group of patients was divided based on history of kidney transplantation. Again, we confirmed significant improvement in hemoglobin levels in kidney transplantation group in first month of treatment (P &amp;lt; 0.0001) as well as in follow up (P &amp;lt; 0.0001). There was a significant improvement in hemoglobin levels in the first month of roxadustat treatment in the group of patients who did not undergo kidney transplantation (P = 0.0261). However, there was no significant difference between hemoglobin levels in month 1 and follow up in this group. Conclusion Roxadustat—as a new treatment option of anaemia for patients with chronic kidney diseases. Our first analysis confirmed that roxadustat is very effective not only in patients with CKD, but also in patients with anaemia after kidney transplantation.

#1948 Transcriptome analysis of the effect of roxadustat on osteoclasts

Abstract Background and Aims In recent years, hypoxia-inducing factor prolyl hydroxylase inhibitors (HIF-PHIs) have been widely used in the treatment of renal anemia, bringing a revolutionary breakthrough in the treatment of anemia in CKD patients. However, HIF-PHIs acts on a variety of cells and regulates the expression of multiple target genes. Some studies have reported that HIF-PHIs plays an important role in regulating bone metabolism and promoting the differentiation and calcification of osteoblasts, but its influence on osteoclasts remains controversial. This study intends to explore the effect of roxadustat, a representative drug of HIF-PHIs, on osteoclasts. Method Bone marrow mononuclear cells (BMMCs) from 6-8 weeks old male C57BL/6 wild mice were extracted and induced to differentiate into osteoclasts using macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL). Meanwhile, lipopolysaccharide (LPS) was used to simulate the inflammatory environment in CKD patients. According to the experimental group, different concentrations of roxadustat (0 μM, 2.5 μM, 5 μM, 10μM) were added simultaneously. When osteoclast induction reached day 6, mRNA was extracted for transcriptome sequencing and bioinformatics analysis. Results As shown in Table 1, different concentrations of roxadustat were given to primary bone marrow monocytes under both conditions, and there were 3 biological replicates for each sample. The reproducibility scatter plot showed that the data in each group had good repeatability (Fig. 1), and the heat map for basic difference analysis of each sample was shown in Fig. 2. The trend analysis results of the two groups were shown in Fig. 3. BMMCs group and LPS stimulated group showed two upward trends, respectively. KEGG enrichment analysis of these two upward trends showed that HIF-1, MAPK, PI3K-Akt, NF-κB and osteoclast differentiation pathways were significantly enriched in both groups. It is suggested that roxadustat can promote osteoclast differentiation and increase inflammatory response with the increase of roxadustat concentration. The enrichment analysis of the two groups showed that there was no significant enrichment pathway. Conclusion We explored the differentiation of osteoclasts under normal conditions and osteoclast differentiation under simulated inflammation in CKD patients respectively. Transcriptomic analysis results showed that HIF-1, MAPK, PI3K-Akt, NF-κB and osteoclast differentiation pathways were significantly enriched with the increase of roxadustat concentration. It is suggested that the use of roxadustat may promote bone destruction and increase the risk of inflammatory response.

The comparison of four hypoxia-inducible factor prolyl hydroxylase inhibitors on drug potency and cost for treatment in patients with renal anemia.

Five hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) have been approved for marketing in Japan. However, marked differences exist in terms of drug potency, dose requirement, and pharmacokinetics. The primary evaluation in this study was the changes in hemoglobin levels, dose escalation, drug potency, and cost among HIF-PHIs, 3 months after the initiation of treatment. All patients treated with HIF-PHI between August 2020 and December 2023 were enrolled in this study. In total, 124 patients were administered daprodustat (N = 37), enarodustat (N = 44), molidustat (N = 13), or vadadustat (N = 30). The mean hemoglobin levels of daprodustat, enarodustat, molidustat, and vadadustat at 3 months were 11.7g/dL, 11.8g/dL, 12.2g/dL, and 11.3g/dL, respectively. At 3 months, the mean doses of daprodustat, enarodustat, molidustat, and vadadustat increased by 110%, 177%, 125%, and 152%, respectively, from the initial dose. The HIF-PHI potency indices (HPI) of daprodustat, enarodustat, molidustat, and vadadustat at 3 months were 0.168, 0.307, 0.184, and 0.254, respectively. At 3 months, the mean daily costs of daprodustat, enarodustat, molidustat, and vadadustat were JPY 345, JPY 434, JPY 206, and JPY 565, respectively. The difference in dose escalation for anemia treatment among HIF-PHIs is due to differences in drug potency, where the HPI significantly differs among HIF-PHIs. The disparity between the HPI and the cost of the initial dose accounts for the variance in the daily costs of renal anemia treatment among HIF-PHIs.

Critical re-evaluation of the identification of iron deficiency states and effective iron repletion strategies in patients with chronic heart failure.

According to current guidelines, iron deficiency is defined by a serum ferritin level <100 ng/ml or a transferrin saturation (TSAT) <20% if the serum ferritin level is 100-299 μg/L. These criteria were developed to encourage the use of intravenous iron as an adjunct to erythropoiesis-stimulating agents in the treatment of renal anaemia. However, in patients with heart failure, these criteria are not supported by any pathophysiological or clinical evidence that they identify an absolute or functional iron deficiency state. A low baseline TSAT-but not serum ferritin level-appears to be a reliable indicator of the effect of intravenous iron to reduce major heart failure events. In randomized controlled trials, intravenous iron decreased the risk of cardiovascular death or total heart failure hospitalization in patients with a TSAT <20% (risk ratio 0.67 [0.49-0.92]) but not in patients with a TSAT ≥20% (risk ratio 0.99 [0.74-1.30]), with the magnitude of the risk reduction being proportional to the severity of hypoferraemia. Patients who were enrolled in clinical trials solely because they had a serum ferritin level <100 μg/L showed no significant benefit on heart failure outcomes, and it is noteworthy that serum ferritin levels of 20-300 μg/L lie entirely within the range of normal values for healthy adults. Current guidelines reflect the eligibility criteria of clinical trials, which inadvertently adopted unvalidated criteria to define iron deficiency. Reliance on these guidelines would lead to the treatment of many patients who are not iron deficient (serum ferritin level <100 μg/L but normal TSAT) and ignores the possibility of iron deficiency in patients with a low TSAT but with serum ferritin level of >300 μg/L. Importantly, analyses of benefit based on trial eligibility-driven guidelines substantially underestimate the magnitude of heart-failure-event risk reduction with intravenous iron in patients who are truly iron deficient. Based on all available data, we recommend a new mechanism-based and trial-tested approach that reflects the totality of evidence more faithfully than the historical process adopted by clinical investigators and by the guidelines. Until additional evidence is forthcoming, an iron deficiency state in patients with heart failure should be defined by a TSAT <20% (as long as the serum ferritin level is <400 μg/L), and furthermore, the use of a serum ferritin level <100 μg/L alone as a diagnostic criterion should be discarded.

A Prospective Randomized Controlled Clinical Study to Investigate the Efficacy and Safety of Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitors in Non-Dialysis Patients with Chronic Heart Failure and Renal Anemia Switched from Continuous Erythropoietin Receptor Activator Treatment.

Background/Objectives: Chronic kidney disease (CKD) and anemia are independent prognostic factors for heart failure. In recent years, hypoxia-inducible factor-prolyl hydroxylase (HIF-PH) inhibitors have become available for the treatment of renal anemia. This prospective randomized controlled study aimed to investigate the effects of switching from a continuous erythropoietin receptor activator (CERA) to one of four HIF-PH inhibitors in patients with chronic heart failure and renal anemia. Methods: Forty patients were randomized by the envelop method to receive treatment with roxadustat, daprodustat, vadadustat, or molidustat. The primary endpoint was the change in the hemoglobin (Hb) level. Secondary endpoints included changes in erythropoietin, changes in free T3, free T4, and thyroid-stimulating hormone (TSH), adverse effects, and drug dose increases and decreases. This study was preregistered in the University Hospital Medical Information Network Clinical Trials Registry (study ID: UMIN000041651). Results: We found no statistically significant difference between Hb levels with HIF-PH inhibitors and CERA, but at month 6, the Hb level was significantly higher with roxadustat than with vadadustat and daprodustat. Erythropoietin decreased significantly after switching to HIF-PH inhibitors. HIF-PH inhibitors had various significant effects on free T3, free T4, and TSH. No adverse events occurred. The doses of some drugs had to be increased or decreased. Conclusions: In patients with heart failure and renal anemia receiving CERA, Hb, NT-ProBNP, and renal function were similar after switching from CERA to HIF-PH inhibitors. The individual HIF-PH inhibitors appear to have different effects on anemia and thyroid function. However, because this was a single-center study with a limited sample size, the efficacy and potential limitations of HIF-PH inhibitors need to be further clarified.

A lentivirus-vectored feline erythropoietin gene therapy strategy in tissue culture and rodent models for the potential treatment of chronic renal disease-associated anemia.

The aim of this study was to assess the efficacy and safety of a third-generation lentivirus-based vector encoding the feline erythropoietin (EPO) (feEPO) gene in vitro and in rodent models in vivo. This vector incorporates a genetic mechanism to facilitate the termination of the therapeutic effect in the event of supraphysiologic polycythemia, the herpes simplex virus thymidine kinase (HSV-TK) "suicide gene." CFRK cells and replication-defective lentiviral vectors encoding feEPO were used for in vitro experiments. Eight Fischer rats were enrolled in the pilot in vivo study, 24 EPO-deficient mice were used in the initial mouse study, and 15 EPO-deficient mice were enrolled in the final mouse study. Efficacy of a third-generation lentivirus encoding feEPO was determined in vitro using western blot assays. Subsequently, in a series of rodent experiments, animals were administered the viral vector in progressively increasing inoculation doses with serial measurements of blood packed cell volume (PCV) over time. We documented production of feEPO protein in transduced CRFK cells with subsequent cessation of production when treated with the HSV-TK substrate ganciclovir. In vivo, we demonstrated variably persistent elevated PCV values in treated rats and mice with eventual return to baseline values over time. These results provide justification for a lentiviral gene therapy approach to the treatment of nonregenerative anemia associated with chronic renal disease in cats.

The drug-specific properties of hypoxia-inducible factor-prolyl hydroxylase inhibitors in mice reveal a significant contribution of the kidney compared to the liver to erythropoietin induction

AimsKidney disease often leads to anemia due to a defect in the renal production of the erythroid growth factor erythropoietin (EPO), which is produced under the positive regulation of hypoxia-inducible transcription factors (HIFs). Chemical compounds that inhibit HIF-prolyl hydroxylases (HIF-PHs), which suppress HIFs, have been developed to reactivate renal EPO production in renal anemia patients. Currently, multiple HIF-PH inhibitors, in addition to conventional recombinant EPO reagents, are used for renal anemia treatment. This study aimed to elucidate the therapeutic mechanisms and drug-specific properties of HIF-PH inhibitors. Methods and key findingsGene expression analyses and mass spectrometry revealed that HIF-PH inhibitors (daprodustat, enarodustat, molidustat, and vadadustat) alter Epo gene expression levels in the kidney and liver in a drug-specific manner, with different pharmacokinetics in the plasma and urine after oral administration to mice. The drug specificity revealed the dominant contribution of EPO induction in the kidneys rather than in the liver to plasma EPO levels after HIF-PH inhibitor administration. We also found that several HIF-PH inhibitors directly induce duodenal gene expression related to iron intake, while these drugs indirectly suppress hepatic hepcidin expression to mobilize stored iron for hemoglobin synthesis through induction of the EPO-erythroferrone axis. SignificanceRenal EPO induction is the major target of HIF-PH inhibitors for their therapeutic effects on erythropoiesis. Additionally, the drug-specific properties of HIF-PH inhibitors in EPO induction and iron metabolism have been shown in mice, providing useful information for selecting the proper HIF-PH inhibitor for each renal anemia patient.

PHD1-3 oxygen sensors in vivo-lessons learned from gene deletions.

Oxygen sensors enable cells to adapt to limited oxygen availability (hypoxia), affecting various cellular and tissue responses. Prolyl-4-hydroxylase domain 1-3 (PHD1-3; also called Egln1-3, HIF-P4H 1-3, HIF-PH 1-3) proteins belong to the Fe2+- and 2-oxoglutarate-dependent dioxygenase superfamily and utilise molecular oxygen (O2) alongside 2-oxoglutarate as co-substrate to hydroxylate two proline residues of α subunits of the dimeric hypoxia inducible factor (HIF) transcription factor. PHD1-3-mediated hydroxylation of HIF-α leads to its degradation and inactivation. Recently, various PHD inhibitors (PHI) have entered the clinics for treatment of renal anaemia. Pre-clinical analyses indicate that PHI treatment may also be beneficial in numerous other hypoxia-associated diseases. Nonetheless, the underlying molecular mechanisms of the observed protective effects of PHIs are only partly understood, currently hindering their translation into the clinics. Moreover, the PHI-mediated increase of Epo levels is not beneficial in all hypoxia-associated diseases and PHD-selective inhibition may be advantageous. Here, we summarise the current knowledge about the relevance and function of each of the three PHD isoforms in vivo, based on the deletion or RNA interference-mediated knockdown of each single corresponding gene in rodents. This information is crucial for our understanding of the physiological relevance and function of the PHDs as well as for elucidating their individual impact on hypoxia-associated diseases. Furthermore, this knowledge highlights which diseases may best be targeted by PHD isoform-selective inhibitors in case such pharmacologic substances become available.

Growing concerns about using hypoxia-inducible factor prolyl hydroxylase inhibitors for the treatment of renal anemia.

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) have emerged as a novel therapeutic class for treating anemia in patients with chronic kidney disease. Small molecule analogs of α-ketoglutarate (AKG), an essential substrate for 2-oxoglutarate-dependent dioxygenases (2-OGDDs), including prolyl hydroxylase domain proteins (PHDs), inhibit PHDs pharmacologically and thereby prevent HIF degradation. HIF stabilization alleviates anemia through several stimulatory effects on erythropoiesis, but it also affects the expression of many anemia-unrelated genes whose protein products exert important functions in vivo. Therefore, the pleiotropic effects of HIF stabilization under normoxic conditions deserve to be examined in more detail. Specifically, we believe that particular attention should be given to epigenetic modifications among the various AKG-based metabolic systems that may be altered by HIF-PHIs. It is noteworthy that AKG has been reported to exert health-protective actions. AKG-based metabolic systems include enzymes associated with the tricarboxylic acid cycle and amino acid metabolism, as well as 2-OGDD-mediated processes, which play important roles in many biological reactions. In this review, we examine the multifaceted effects of HIF-PHIs, encompassing not only their on-target effect of HIF stabilization but also their off-target inhibitory effects on various AKG-based metabolic systems. Furthermore, we examine its potential relevance to cardiovascular complications, based on clinical and animal studies suggesting its involvement in vascular calcification, thrombogenesis and heart failure. In conclusion, although HIF-PHIs offer a promising avenue for anemia treatment in CKD patients, their broader impact on multiple biological systems raises substantial concerns. The intricate interplay between HIF stabilization, AKG competition and cardiovascular complications warrants extensive, long-term investigations to ensure the safety and usefulness of HIF-PHIs in clinical practice.