Effect of Moderate Hepatic Impairment on the Pharmacokinetics of Vadadustat, an Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor.

Vadadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor in development for the treatment of anemia of chronic kidney disease. This phase 1, open-label, parallel-group, single-dose study evaluated the pharmacokinetics of 450-mg vadadustat in adults with moderate hepatic impairment (Child-Pugh class B) vs those with normal hepatic function. Primary end points were area under the plasma concentration-time curve (AUC) from dosing to last concentration and to infinity, as well as maximum concentration (Cmax ); additional pharmacokinetic parameters included time to Cmax (Tmax ) and half-life. Safety and tolerability were also assessed. All enrolled participants (n = 16) completed the study. Demographics were similar in both groups (overall, 100% White; 62.5% female; mean age, 59.2 years). Vadadustat plasma exposure was higher in the moderate hepatic impairment group, whereas maximum concentration was similar between groups. Point estimates of the hepatic impairment : normal geometric mean ratios (90% confidence interval) for AUC from dosing to last concentration, AUC from dosing to infinity, and Cmax were 1.05 (0.82-1.35), 1.06 (0.82-1.36), and 1.02 (0.79-1.32), respectively. Mean elimination half-life was 5.8 and 7.8 hours in the normal and hepatic impairment groups, respectively. Treatment-emergent adverse events were mostly mild in severity, and vadadustat was generally well tolerated. In conclusion, moderate hepatic impairment did not significantly impact vadadustat systemic exposure, and mild hepatic impairment is unlikely to alter vadadustat exposure.

A validated method for the quantification of IOX-2, a potent prolyl hydroxylase inhibitor in equine urine and plasma using liquid chromatography-high-resolution mass spectrometry.

IOX-2 is a potent inhibitor of enzyme prolyl hydroxylases-2 (PHD) that plays a critical role in regulating hypoxia inducible factor (HIF) abundance and oxygen homeostasis. Federation for Equestrian Sports has listed HIF activators as prohibited substances to prevent their usage in doping. Consequently, it became essential to develop adequate knowledge and testing methods to detect it in equine sports drug testing samples. The validated method utilizes ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry in order to detect extremely low concentration of the analyte present in both matrices. Confirmation for the presence of the analyte was achieved by comparing ion ratios, retention time, and accurate mass. Method linear range for plasma was between 0.25 to 100 ng/ml, and limit of detection (LOD) was 0.075 ng/ml. The linear range for urine was 0.125 to 100 ng/ml, and LOD was 0.025 ng/ml. Intraday precision at 0.5, 10, and 50 ng/ml was between 4.0% and 9.7% for plasma and 4.2% and 10.4% for urine. Accuracy at 0.5, 10, and 50 ng/ml was between 91% and 94% for plasma and 99% and 103% for urine. Elimination profile of IOX-2 in equine plasma and urine was carried out using the developed method in which two horses were intravenously administered IOX-2 and samples were collected. Metabolic profile in plasma and urine was investigated. IOX-2 was detected for a minimum of 54 and 151 h of post administration in plasma and urine, respectively, thereby providing a valuable tool for evaluating its misuse in equine racing.

Iron Therapy in Chronic Kidney Disease: Days of Future Past.

Anemia affects millions of patients with chronic kidney disease (CKD) and prompt iron supplementation can lead to reductions in the required dose of erythropoiesis-stimulating agents, thereby reducing medical costs. Oral and intravenous (IV) traditional iron preparations are considered far from ideal, primarily due to gastrointestinal intolerability and the potential risk of infusion reactions, respectively. Fortunately, the emergence of novel iron replacement therapies has engendered a paradigm shift in the treatment of iron deficiency anemia in patients with CKD. For example, oral ferric citrate is an efficacious and safe phosphate binder that increases iron stores to maintain hemoglobin levels. Additional benefits include reductions in fibroblast growth factor 23 levels and the activation of 1,25 dihydroxyvitamin D. The new-generation IV iron preparations ferumoxytol, iron isomaltoside 1000, and ferric carboxymaltose are characterized by a reduced risk of infusion reactions and are clinically well tolerated as a rapid high-dose infusion. In patients undergoing hemodialysis (HD), ferric pyrophosphate citrate (FPC) administered through dialysate enables the replacement of ongoing uremic and HD-related iron loss. FPC transports iron directly to transferrin, bypassing the reticuloendothelial system and avoiding iron sequestration. Moreover, this paper summarizes recent advancements of hypoxia-inducible factor prolyl hydroxylase inhibitors and future perspectives in renal anemia management.

Enarodustat: First Approval.

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

Effect of Kidney Function and Dialysis on the Pharmacokinetics and Pharmacodynamics of Roxadustat, an Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor.

BACKGROUND AND OBJECTIVES: Roxadustat is an orally active hypoxia-inducible factor prolyl hydroxylase inhibitor for anemia in chronic kidney disease. The pharmacokinetics, metabolic profile, and pharmacodynamics of roxadustat were investigated in subjects with different degrees of kidney function. METHODS: This phase 1 open-label study enrolled subjects with normal and severely impaired kidney function, and end-stage renal disease (ESRD) on continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD) or hemodialysis/hemodiafiltration (HD/HDF). All subjects received a single 100-mg dose of oral roxadustat. Within a single-sequence, two-treatment period design (P1/P2), subjects with ESRD on HD/HDF received roxadustat 2 h after (P1) and 2 h before (P2) a dialysis session. Area under the plasma concentration-time curve (AUC) from administration to infinity (AUCinf), maximum concentration (Cmax), and terminal elimination half-life (t1/2) were assessed for roxadustat; AUC and Cmax were assessed for erythropoietin. RESULTS: Thirty-four subjects were enrolled and received roxadustat (normal kidney function, n = 12; severely impaired kidney function, n = 9; ESRD on CAPD/APD, n = 1; ESRD on HD/HDF, n = 12). The geometric least-square mean ratio of AUCinf was 223% and 195% in subjects with severely impaired kidney function and ESRD on HD/HDF, respectively, relative to subjects with normal kidney function; Cmax and t1/2 were comparable. The pharmacokinetic profile of roxadustat was not affected by HD/HDF. AUCinf and t1/2 for the metabolites of roxadustat increased in subjects with kidney impairment. The AUC and Cmax of erythropoietin increased in subjects with severely impaired kidney function or ESRD on HD/HDF. Roxadustat was well tolerated. CONCLUSIONS: Kidney function impairment increased the AUC of roxadustat and its metabolites. The Cmax and t1/2 of roxadustat were comparable among groups. Roxadustat and its metabolites were not cleared by HD/HDF. Clinical Trials Registration Number: NCT02965040.

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

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

Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor Roxadustat (FG-4592) for Treatment of Anemia in Chronic Kidney Disease: A Placebo-Controlled Study of Pharmacokinetic and Pharmacodynamic Profiles in Hemodialysis Patients.

Roxadustat (FG-4592), an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that stimulates erythropoiesis, was evaluated in a phase 1b study in patients with end-stage renal disease with anemia on hemodialysis. Seventeen patients, on epoetin-alfa maintenance therapy with stable hemoglobin levels ≥10 g/dL, had epoetin-alfa discontinued on day 3 and were enrolled in this double-blind placebo-controlled study. Two cohorts were randomized 3:1 (roxadustat: placebo). Patients received single doses of roxadustat (1 or 2 mg/kg) or placebo 1 hour after hemodialysis on day 1 and 2 hours before dialysis on day 8. Maximum plasma concentration and area under the plasma concentration-time curve for patients receiving roxadustat were slightly more than dose proportional and elimination half-life ranged from 14.7 to 19.4 hours. Roxadustat was highly protein bound (99%) in plasma, and dialysis contributed a small fraction of the total clearance: only 4.56% and 3.04% of roxadustat recovered from the 1 and 2 mg/kg dose groups, respectively. Roxadustat induced transient elevations of endogenous erythropoietin that peaked between 7 and 14 hours after dosing and returned to baseline by 48 hours after dosing. Peak median endogenous erythropoietin levels were 96 mIU/mL and 268 mIU/mL for the 1- and 2-mg/kg doses, respectively, within physiologic range of endogenous erythropoietin responses to hypoxia at high altitude or after blood loss. No serious adverse events were reported, and there were no treatment- or dose-related trends in adverse event incidence.

Erythropoietin and a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHDi) lowers FGF23 in a model of chronic kidney disease (CKD).

Iron-deficiency anemia is a potent stimulator of the phosphaturic hormone Fibroblast growth factor-23 (FGF23). Anemia, elevated FGF23, and elevated serum phosphate are significant mortality risk factors for patients with chronic kidney disease (CKD). However, the contribution of anemia to overall circulating FGF23 levels in CKD is not understood. Our goal was to investigate the normalization of iron handling in a CKD model using the erythropoiesis stimulating agents (ESAs) Erythropoietin (EPO) and the hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHDi) FG-4592, on the production of, and outcomes associated with, changes in bioactive, intact FGF23 ("iFGF23"). Our hypothesis was that rescuing the prevailing anemia in a model of CKD would reduce circulating FGF23. Wild-type mice were fed an adenine-containing diet to induce CKD, then injected with EPO or FG-4592. The mice with CKD were anemic, and EPO improved red blood cell indices, whereas FG-4592 increased serum EPO and bone marrow erythroferrone (Erfe), and decreased liver ferritin, bone morphogenic protein-6 (Bmp-6), and hepcidin mRNAs. In the mice with CKD, iFGF23 was markedly elevated in control mice but was attenuated by >70% after delivery of either ESA, with no changes in serum phosphate. ESA treatment also reduced renal fibrosis markers, as well as increased Cyp27b1 and reduced Cyp24a1 mRNA expression. Thus, improvement of iron utilization in a CKD model using EPO and a HIF-PHDi significantly reduced iFGF23, demonstrating that anemia is a primary driver of FGF23, and that management of iron utilization in patients with CKD may translate to modifiable outcomes in mineral metabolism.

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

INTRODUCTION: The hypoxia-inducible factor prolyl hydroxylase (HIF-PH) pathway is responsible for regulating the biosynthesis of erythropoietin (EPO) and maintaining iron homeostasis. Investigational drugs that target the HIF-PH pathway are promising alternatives for treating anemia in Chronic Kidney Disease (CKD). AREAS COVERED: This review summarizes recent advances focused on the clinical development of HIF-PH inhibitors (HIF-PHIs) as potentially novel therapies in the treatment of anemia in CKD based on publications available on PubMed and restricted Google searches. We provide a comparison between HIF-PHIs regarding their pharmacokinetics, dosing regimens and safety concerns, structure-activity relationships, and alterations in key laboratory parameters observed in animal models and clinical trials. EXPERT OPINION: HIF-PHIs may be advantageous in some aspects compared to the conventional erythropoiesis-stimulating agents (ESAs). While ESAs could increase the risk of cardiovascular events due to rapid rises in ESA blood levels, HIF-PHIs have been reported to maintain EPO concentrations at levels that are closer to the normal physiological ranges. Although HIF-PHIs have been demonstrated to be relatively safe and effective in clinical trials, long-term safety data are needed in order to establish whether these therapeutic agents will lead to a major paradigm change in the treatment of anemia of CKD.

A Phase 3, Multicenter, Randomized, Two-Arm, Open-Label Study of Intermittent Oral Dosing of Roxadustat for the Treatment of Anemia in Japanese Erythropoiesis-Stimulating Agent-Naïve Chronic Kidney Disease Patients Not on Dialysis.

INTRODUCTION: Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved for the treatment of anemia in Japan for patients with dialysis-dependent (DD) chronic kidney disease (CKD). OBJECTIVE: Multicenter, randomized, open-label, noncomparative, phase 3 study to evaluate roxadustat for anemia of non-dialysis-dependent (NDD) CKD in Japan. METHODS: Erythropoiesis stimulating agent (ESA)-naïve NDD-CKD patients were randomized to roxadustat (initial dose, 50 or 70 mg 3 times weekly), titrated to maintain hemoglobin (Hb) within 10.0-12.0 g/dL, for ≤24 weeks. Patients with either transferrin saturation of ≥5% or serum ferritin of ≥30 ng/mL during the screening period were eligible. Endpoints included response rate (proportion of patients achieving Hb ≥10.0 or ≥10.5 g/dL and Hb increase ≥1.0 g/dL from baseline) at end of treatment; average Hb (weeks 18-24); change of average Hb from baseline to weeks 18-24; maintenance rate (proportion of patients achieving Hb 10.0-12.0 g/dL at weeks 18-24); rate of rise (RoR) of Hb from weeks 0-4, discontinuation, or dose adjustment. Adverse events were monitored throughout the study. RESULTS: Of 135 patients who provided informed consent, 100 were randomized and 99 received roxadustat (50 mg, n = 49; 70 mg, n = 50). The mean (SD) dose of roxadustat per intake at week 22 was 36.3 (22.7) mg in the roxadustat 50 mg group and 36.8 (16.0) mg in the roxadustat 70 mg group. Prior medications included oral iron therapy (20.2%) and intravenous iron therapy (1.0%). Overall response rate (95% CI) was 97.0% (91.4, 99.4; Hb ≥10.0 g/dL) and 94.9% (88.6, 98.3; Hb ≥10.5 g/dL). Mean (SD) Hb (weeks 18-24) was 11.17 (0.62) g/dL. Mean (SD) change of Hb from baseline (weeks 18-24) was 1.34 (0.86) g/dL. Maintenance rate (95% CI) was 88.8% (80.3, 94.5) among patients with ≥1 Hb measurement during weeks 18-24. Mean (SD) RoR of Hb was 0.291 (0.197) g/dL/week (50 mg) and 0.373 (0.235) g/dL/week (70 mg). Nasopharyngitis and hypertension were the most common adverse events. CONCLUSION: Roxadustat increased and maintained Hb in ESA-naïve, partially iron-depleted NDD-CKD patients with anemia.

A Single-Dose, Open-Label, Randomized, Two-Way Crossover Study in Healthy Japanese Participants to Evaluate the Bioequivalence and the Food Effect on the Pharmacokinetics of Daprodustat.

Daprodustat is a prolyl hydroxylase inhibitor that stimulates erythropoiesis in a manner similar to the natural response to hypoxia, whereby inhibition of hypoxia inducible factor (HIF) prolyl-4-hydroxylases by daprodustat ultimately results in increased levels of HIF-responsive genes. Daprodustat is under development as an emerging new class of agents for the treatment of anemia associated with chronic kidney disease (CKD). This was a single-center, single-dose, open-label, randomized, 2-way crossover study in healthy Japanese male participants consisting of 2 parts. The primary objective was to evaluate the bioequivalence (BE) between daprodustat tablet strengths (part 1) and to evaluate the food effect on the pharmacokinetics (PK) of daprodustat (part 2). A total of 64 healthy Japanese male participants were enrolled; 52 participants were included in part 1 and 12 in part 2. BE was demonstrated between the daprodustat 2-mg tablet and the daprodustat 4-mg tablet. A standard CKD meal did not have a large effect on the PK parameters of daprodustat after a single oral dose of daprodustat 4 mg. Administration of single oral doses of daprodustat 4 mg was generally well tolerated in the healthy Japanese participants, and no new safety signals were identified without regard to food.

Effects of orally active hypoxia inducible factor alpha prolyl hydroxylase inhibitor, FG4592 on renal fibrogenic potential in mouse unilateral ureteral obstruction model.

Orally active hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitors that stabilize HIF protein and stimulate the production of erythropoietin have been approved to treat renal anemia. Our previous report suggested that HIF-1α dependent fibrogenic mechanisms are operating at the early onset of renal fibrosis and its contribution declines with the progression in mouse unilateral ureteral obstruction (UUO) model. The aim of the study is to evaluate the renal fibrogenic potential of FG4592, a recently approved orally active HIF prolyl hydroxylase inhibitor in mouse UUO model. Male C57BL/6J mice orally given FG-4592 (12.5 mg/kg/day and 50 mg/kg/day) were subjected to UUO. Neither dose of FG-4592 affected renal fibrosis or macrophage infiltration. FG-4592 had no effects on increased mRNA of collagen I, collagen III or transforming growth factor-ß1. At 3 days after UUO, higher dose of FG-4592 potentiated the increased mRNA expression of profibrogenic molecules, plasminogen activator inhibitor 1 (Pai-1) and connective tissue growth factor (Ctgf) but such potentiation disappeared at 7 days after UUO. It is suggested that FG-4592 used in the present study had little effects on renal fibrosis even though high dose of FG-4592 used in the present study transiently potentiated gene expression of Pai-1 and Ctgf in the UUO kidney.

A Mass Balance Study of 14 C-Labeled JTZ-951 (Enarodustat), a Novel Orally Available Erythropoiesis-Stimulating Agent, in Patients With End-Stage Renal Disease on Hemodialysis.

The mass balance, pharmacokinetics, and biotransformation of JTZ-951 (enarodustat), a novel hypoxia-inducible factor prolyl hydroxylase inhibitor, were characterized in patients (N = 6) with end-stage renal disease on hemodialysis. Following a 10-mg (100 µCi) oral dose of 14 C-JTZ-951, whole blood, feces, dialysate, and, if feasible, urine were obtained for pharmacokinetic assessments and for metabolite profiling and identification in appropriate matrices. Fecal excretion was the major route of elimination of radioactivity, and urinary excretion a minor route, with mean (coefficient of variation [%CV]) recovery of 77.1 (16.2)% and 10.9 (92.0)% of the dose, respectively. Radioactivity was not detected in the dialysate, and mean (%CV) total recovery in excreta was 88.0 (14.9)%. For parent JTZ-951 in plasma, the mean (%CV) effective half-life was 8.96 (7.7)% hours, and area under the curve over 24 hours comprised the majority (>80%) of total exposure, with relatively low variability in these pharmacokinetic variables. Based on profiling of plasma radioactivity, parent JTZ-951 was the predominant circulating component, accounting for 93.7% or more of radioactivity, and metabolite M2 (hydroxylated product) was the only detectable metabolite, but its exposure was minor (<5%) versus unchanged JTZ-951. In urine and feces, the predominant analyte was JTZ-951, and metabolite M2 was the predominant albeit minor metabolite, with small amounts of other metabolites. Thus, plasma exposure to drug-derived radioactivity was primarily due to parent JTZ-951, and the drug was cleared mainly by excretion of unchanged JTZ-951. The study appropriately characterized the disposition of JTZ-951 in patients with end-stage renal disease.

Iron Regulation by Molidustat, a Daily Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor, in Patients with Chronic Kidney Disease.

BACKGROUND/AIMS: The current treatment for anemia associated with chronic kidney disease (CKD) includes the administration of erythropoiesis stimulating agents (ESAs) combined with iron supplementation. Molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, has potential to treat anemia associated with CKD through increased erythropoietin production and improved iron availability. Here, we report the effect of molidustat on iron metabolism. METHOD: Parameters of iron metabolism were monitored in three 16-week, randomized, controlled, phase 2 studies assessing the safety and efficacy of molidustat in the treatment of anemia associated with CKD in different populations: treatment-naïve and previously ESA-treated patients not on dialysis, and previously ESA-treated patients on hemodialysis. Iron supplementation was left at the discretion of the investigator. RESULTS: In treatment-naïve patients not on dialysis, transferrin saturation (TSAT), hepcidin, ferritin, and iron concentrations decreased with molidustat, whereas total iron binding capacity (TIBC) increased. Similar results were observed in previously ESA-treated patients not on dialysis, although changes in those parameters were larger in treatment-naïve than in previously ESA-treated patients. In previously ESA-treated patients receiving hemodialysis, hepcidin concentration and TIBC remained stable with molidustat, whereas TSAT and ferritin and iron concentrations increased. Generally, similar trends were observed in secondary analyses of subgroups of patients not receiving iron supplementation. CONCLUSIONS: Molidustat is a potential alternative to standard treatment of anemia associated with CKD, with a different mechanism of action. In patients not receiving dialysis, molidustat increases iron availability. In patients receiving hemodialysis, further investigation is required to understand fully the mechanisms underlying iron mobilization associated with molidustat.

Roxadustat: First Global Approval.

Roxadustat (Ai Rui Zhuo® in China) is an orally administered, small molecule hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor that is being developed by FibroGen, in collaboration with Astellas and AstraZeneca, for the treatment of anaemia in patients with dialysis-dependent chronic kidney disease (CKD), non-dialysis-dependent CKD and in patients with myelodysplastic syndromes. The drug reversibly binds to and inhibits HIF-prolyl hydroxylase enzymes that are responsible for the degradation of transcription factors in the HIF family under normal oxygen conditions. Inhibition of these enzymes reduces HIF breakdown and promotes HIF activity, leading to an increase in endogenous erythropoietin production, thereby enhancing erythropoiesis. It also reduces the expression of the peptide hormone hepcidin, improves iron availability and increases haemoglobin levels. HIF regulates the expression of genes in response to reduced oxygen levels, including genes required for erythropoiesis and iron metabolism. Roxadustat is approved in China and is under regulatory review in Japan for the treatment of anaemia in patients with dialysis-dependent CKD. Studies are underway to investigate long-term cardiovascular outcomes with roxadustat versus placebo (for non-dialysis-dependent CKD) or standard of care (for dialysis-dependent CKD). This article summarizes the milestones in the development of roxadustat leading to this first approval.

Investigational hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) for the treatment of anemia associated with chronic kidney disease.

INTRODUCTION: In the last decade, concerns have been raised around the use of erythropoiesis-stimulating agents (ESAs) and intravenous iron in chronic kidney disease (CKD) patients, especially when given at high doses. Moreover, treatment with ESA is expensive. AREAS COVERED: We searched PubMed for original articles, reviews, and editorials having as a topic anemia, CKD, hypoxia inducible factor, hepcidin, iron, and hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI). HIF-PHI are a new class of small molecules activating HIF-alfa isoforms (the main mediators of the effects of hypoxia on the body). This causes the secretion of endogenous erythropoietin and increased iron availability. Differing from ESA, HIF-PHI are administered orally. Preliminary data from phase-II clinical studies have shown their efficacy and safety in the short term. EXPERT OPINION: HIF-PHI are a new promising class of drugs. The results of large, phase-III clinical studies are awaited to prove their efficacy and safety on cardiovascular events and cancer development in the long term. Their capability of penetrating the ESA market in the future will be influenced also by their selling price. The oral administration of HIF-PHI will be weighed to the 'intra-lines' infusion of ESA in hemodialysis or to the infrequent subcutaneous injections of long-acting ESA.

Click Chemistry-Based Discovery of [3-Hydroxy-5-(1 H-1,2,3-triazol-4-yl)picolinoyl]glycines as Orally Active Hypoxia-Inducing Factor Prolyl Hydroxylase Inhibitors with Favorable Safety Profiles for the Treatment of Anemia.

As a gene associated with anemia, the erythropoiesis gene is physiologically expressed under hypoxia regulated by †hypoxia-inducing factor-α (HIF-α). Thus, stabilizing HIF-α is a potent strategy to stimulate the expression and secretion of erythropoiesis. In this study, we applied click chemistry to the discovery of HIF prolyl hydroxylase 2 (HIF-PHD2) inhibitors for the first time, and a series of triazole compounds showed preferable inhibitory activity in fluorescence polarization assays. Of particular note was the orally active HIF-PHD inhibitor 15i (IC50 = 62.23 nM), which was almost ten times more active than the phase III drug FG-4592 (IC50 = 591.4 nM). Furthermore, it can upregulate the hemoglobin of cisplatin-induced anemia mice (120 g/L) to normal levels (160 g/L) with no apparent toxicity observed in vivo. These results confirm that triazole compound 15i is a promising candidate for the treatment of renal anemia.

Discovery of novel 2-[(4-hydroxy-6-oxo-2,3-dihydro-1H-pyridine-5-carbonyl)amino]acetic acid derivatives as HIF prolyl hydroxylase inhibitors for treatment of renal anemia.

Prolyl hydroxylase domain-containing protein (PHD) inhibitors are useful as orally administered agents for the treatment of renal anemia. Based on the common structures of known PHD inhibitors, we found novel PHD inhibitor 1 with a 2-[(4-hydroxy-6-oxo-2,3-dihydro-1H-pyridine-5-carbonyl)amino]acetic acid motif. The PHD2-inhibitory activity, lipophilicity (CLogP), and PK profiles (hepatocyte metabolism, protein binding, and/or elimination half-life) of this inhibitor were used as the evaluation index to optimize the structure and eventually discovered clinical candidate 42 as the suitable compound. Compound 42 was demonstrated to promote the production of erythropoietin (EPO) following oral administration in mice and rats. The predicted half-life of this compound in humans was 1.3-5.6 h, therefore, this drug may be expected to administer once daily with few adverse effects caused by excessive EPO production.

First-in-man-proof of concept study with molidustat: a novel selective oral HIF-prolyl hydroxylase inhibitor for the treatment of renal anaemia.

AIMS: Insufficient erythropoietin (EPO) synthesis is a relevant cause of renal anaemia in patients with chronic kidney disease. Molidustat, a selective hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor, increases endogenous EPO levels dose dependently in preclinical models. We examined the pharmacokinetics, safety, tolerability and effect on EPO levels of single oral doses of molidustat in healthy male volunteers. METHODS: This was a single-centre, randomized, single-blind, placebo-controlled, group-comparison, dose-escalation study. Molidustat was administered at doses of 5, 12.5, 25, 37.5 or 50 mg as a polyethylene glycol-based solution. RESULTS: In total, 45 volunteers received molidustat and 14 received placebo. Molidustat was absorbed rapidly, and the mean maximum plasma concentration and area under the concentration-time curve increased dose dependently. The mean terminal half-life was 4.64-10.40 h. A significant increase in endogenous EPO was observed following single oral doses of molidustat of 12.5 mg and above. Geometric mean peak EPO levels were 14.8 IU l-1 (90% confidence interval 13.0, 16.9) for volunteers who received placebo and 39.8 IU l-1 (90% confidence interval: 29.4, 53.8) for those who received molidustat 50 mg. The time course of EPO levels resembled the normal diurnal variation in EPO. Maximum EPO levels were observed approximately 12 h postdose and returned to baseline after approximately 24-48 h. All doses of molidustat were well tolerated and there were no significant changes in vital signs or laboratory safety parameters. CONCLUSIONS: Oral administration of molidustat to healthy volunteers elicited a dose-dependent increase in endogenous EPO. These results support the ongoing development of molidustat as a potential new treatment for patients with renal anaemia.