CIRP attenuates acute kidney injury after hypothermic cardiovascular surgery by inhibiting PHD3/HIF-1α-mediated ROS-TGF-ß1/p38 MAPK activation and mitochondrial apoptotic pathways.

BACKGROUND: The ischemia-reperfusion (IR) environment during deep hypothermic circulatory arrest (DHCA) cardiovascular surgery is a major cause of acute kidney injury (AKI), which lacks preventive measure and treatment. It was reported that cold inducible RNA-binding protein (CIRP) can be induced under hypoxic and hypothermic stress and may have a protective effect on multiple organs. The purpose of this study was to investigate whether CIRP could exert renoprotective effect during hypothermic IR and the potential mechanisms. METHODS: Utilizing RNA-sequencing, we compared the differences in gene expression between Cirp knockout rats and wild-type rats after DHCA and screened the possible mechanisms. Then, we established the hypothermic oxygen-glucose deprivation (OGD) model using HK-2 cells transfected with siRNA to verify the downstream pathways and explore potential pharmacological approach. The effects of CIRP and enarodustat (JTZ-951) on renal IR injury (IRI) were investigated in vivo and in vitro using multiple levels of pathological and molecular biological experiments. RESULTS: We discovered that Cirp knockout significantly upregulated rat Phd3 expression, which is the key regulator of HIF-1α, thereby inhibiting HIF-1α after DHCA. In addition, deletion of Cirp in rat model promoted apoptosis and aggravated renal injury by reactive oxygen species (ROS) accumulation and significant activation of the TGF-ß1/p38 MAPK inflammatory pathway. Then, based on the HK-2 cell model of hypothermic OGD, we found that CIRP silencing significantly stimulated the expression of the TGF-ß1/p38 MAPK inflammatory pathway by activating the PHD3/HIF-1α axis, and induced more severe apoptosis through the mitochondrial cytochrome c-Apaf-1-caspase 9 and FADD-caspase 8 death receptor pathways compared with untransfected cells. However, silencing PHD3 remarkably activated the expression of HIF-1α and alleviated the apoptosis of HK-2 cells in hypothermic OGD. On this basis, by pretreating HK-2 and rats with enarodustat, a novel HIF-1α stabilizer, we found that enarodustat significantly mitigated renal cellular apoptosis under hypothermic IR and reversed the aggravated IRI induced by CIRP defect, both in vitro and in vivo. CONCLUSION: Our findings indicated that CIRP may confer renoprotection against hypothermic IRI by suppressing PHD3/HIF-1α-mediated apoptosis. PHD3 inhibitors and HIF-1α stabilizers may have clinical value in renal IRI.

Evaluation of the Carcinogenic Potential of Enarodustat (JTZ-951), a Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitor, in 26-Week Tg.rasH2 Mouse Study and 2-Year Sprague-Dawley Rat Study.

Enarodustat (JTZ-951) is an oral hypoxia-inducible factor-prolyl hydroxylase (HIF-PH) inhibitor for the treatment of anemia with chronic kidney disease. Carcinogenicity of enarodustat was evaluated in a 26-week repeated oral dose study in Transgenic rasH2 (Tg.rasH2) mice and a 2-year repeated oral dose study in Sprague-Dawley (SD) rats. The highest dose levels were set at 6 mg/kg in the Tg.rasH2 mouse study and at 1 mg/kg in the SD rat study based on the maximum tolerated doses in the 3-month and 6-month dose-range finding studies, respectively. Enarodustat did not increase the incidence of any tumors or affect survival in these carcinogenicity studies. Pharmacology-related findings including increases in blood RBC parameters were observed at the highest dose levels for each study. The AUC-based exposure margins as protein-unbound drug base are 16.3-/26.0-fold multiple (males/females) for Tg.rasH2 mice and 1.6-/1.1-fold multiple for SD rats when compared with the estimated exposure in human with chronic kidney disease at 8 mg/day (maximum recommended human dose). In conclusion, enarodustat was considered to have no carcinogenic potential at the clinical dose.

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

The National Kidney Foundation convened an interdisciplinary international workshop in March 2019 to discuss the potential role of a new class of agents for the treatment of anemia in patients with chronic kidney disease (CKD): the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). International experts with expertise in physiology, biochemistry, structural chemistry, translational medicine, and clinical management of anemia participated. Participants reviewed the unmet needs of current anemia treatment, the biology of hypoxia-inducible factor, the pharmacology of prolyl hydroxylase inhibitors, and the results of phase 2 clinical trials of HIF-PHIs among patients with CKD, both those treated by dialysis and those not receiving kidney replacement therapy. The results of key phase 3 clinical trials of HIF-PHIs available as of the time of writing are also included in this report, although they appeared after the workshop was completed. Participants in the workshop developed a number of recommendations for further examination of HIF-PHIs, which are summarized in this report and include long-term safety issues, potential benefits, and practical considerations for implementation including patient and provider education.

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

WHAT IS KNOWN AND OBJECTIVE: Previous studies based on small-sample clinical data proved that short-term use of hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitors increased haemoglobin levels in anaemic patients with chronic kidney disease (CKD). However, these studies reached conflicting conclusions on iron parameters and adverse event profiles. Our meta-analysis aimed to evaluate the long-term efficacy and safety of HIF-PHD inhibitors in renal anaemia. METHODS: Randomized controlled trials comparing treatment with HIF-PHD inhibitors versus placebo or erythropoiesis-stimulating agents (ESAs) were thoroughly searched in the PubMed, Embase, Cochrane Library and international clinical trial registries. Meta-analysis was performed on main outcomes with random effects models. RESULTS AND DISCUSSION: A total of 30 studies comprising 13,146 patients were included. The HIF-PHD inhibitors used included roxadustat, daprodustat, vadadustat, molidustat, desidustat and enarodustat. HIF-PHD inhibitors significantly increased haemoglobin levels in comparison with placebo [weighted mean difference (WMD) 1.53, 95% confidence interval (CI) 1.39 to 1.67] or ESAs (WMD 0.13, 95% CI 0.03 to 0.22). Hepcidin, ferritin and serum iron levels were decreased, while total iron binding capacity and transferrin levels were increased in the HIF-PHD inhibitor group versus those in placebo or ESAs group. Additionally, HIF-PHD inhibitors medication was associated with cholesterol-lowering effects. As for safety, the risk of serious adverse events in the HIF-PHD inhibitor group was increased in comparison with placebo group [risk ratio (RR) 1.07, 95% CI 1.01 to 1.13], but comparable to the ESAs group (RR 1.02, 95% CI 0.94 to 1.10). Compared with placebo, the agents increased the risk of diarrhoea (1.21, 1.00 to 1.47), nausea (1.46, 1.09 to 1.97), oedema peripheral (1.32, 1.01 to 1.59), hyperkalemia (1.27, 1.05 to 1.54) and hypertension (1.34, 1.02 to 1.76). Compared with ESAs, the drugs increased the risk of vomiting (1.30, 1.02 to 1.65), headache (1.27, 1.05 to 1.53) and thrombosis events (1.31, 1.05 to 1.63). WHAT IS NEW AND CONCLUSION: HIF-PHD inhibitors treatment effectively increased haemoglobin levels and promoted iron utilization in anaemic patients with CKD, and they were well tolerated for long-term use. In order to avoid unfavourable effects of excessive iron consumption, it was appropriate to administer HIF-PHD inhibitors in combination with iron supplements for long-term treatment.

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

BACKGROUND: Enarodustat (JTZ-951) is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that mimics adaptive responses to hypoxic conditions and may provide a new therapeutic approach for managing anemia in patients with chronic kidney disease (CKD). We evaluated the efficacy, safety, and maintenance dose of enarodustat in anemic patients with CKD not on dialysis. METHODS: Erythropoiesis-stimulating agent (ESA) naïve patients (correction group) and patients on a stable dose of ESA (conversion group) were randomized to receive 2, 4, or 6 mg of enarodustat or placebo once daily for 6 weeks in a double-blind manner (Period 1) followed by 24 weeks of open enarodustat treatment to maintain their hemoglobin (Hb) levels within a target range of 10.0-12.0 g/dL in reference to a dose adjustment algorithm (Period 2). RESULTS: In the correction group, Hb level increase rate per week increased in a dose-response manner. The proportion of subjects in the conversion group who maintained Hb levels within ± 1.0 g/dL of baseline did not differ between each enarodustat arm and placebo arm during Period 1. Over 70% of subjects in both groups maintained Hb levels within the target range at the end of treatment in Period 2. The mean prescribed doses were 3.58 and 3.74 mg/day in the correction group and the conversion group, respectively. Enarodustat was associated with decreases in hepcidin and ferritin and increased total iron-binding capacity and was generally well tolerated. CONCLUSIONS: Enarodustat corrects and maintains Hb levels in anemic patients with CKD not on dialysis.

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

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

Pharmacokinetics of Enarodustat in Non-Japanese and Japanese Healthy Subjects and in Patients With End-Stage Renal Disease on Hemodialysis.

The pharmacokinetics of enarodustat were elucidated in healthy subjects and in patients with end-stage renal disease (ESRD) on hemodialysis in phase 1 studies conducted in the United States and Japan. In healthy non-Japanese and Japanese subjects, following single oral administration up to 400 mg, enarodustat was rapidly absorbed. Maximum plasma concentration and area under the plasma concentration-time curve from the time of dosing to infinity were dose-dependent, renal excretion of unchanged enarodustat was substantial (on average ≈45% of dose), and mean t1/2 of <10 hours indicated negligible accumulation with once-daily dosing. In general, with daily dosing (25, 50 mg), accumulation at steady-state was ≈1.5-fold (t1/2(eff) ≈15 hours), presumably due to a decrease in renal drug excretion which is not clinically relevant in patients with ESRD. In the single- and multiple-dose studies, plasma clearance (CL/F) was lower in healthy Japanese subjects. In non-Japanese patients with ESRD on hemodialysis, following once-daily dosing (2-15 mg), enarodustat was rapidly absorbed, steady-state maximum plasma concentration and area under the plasma concentration-time curve during the dosing interval were dose-dependent, and interindividual variability in the exposure parameters was low-to-moderate (coefficient of variation, 27%-39%). Steady-state CL/F was similar across doses, renal drug excretion was not significant (<10% of dose), mean t1/2 and t1/2(eff) were similar (overall, 8.97-11.6 hours), and accumulation was minimal (≈20%), demonstrating predictable pharmacokinetics. Japanese patients with ESRD on hemodialysis (15 mg, single dose) exhibited similar pharmacokinetics with mean t1/2 of 11.3 hours and low interindividual variability in the exposure parameters, albeit with lower CL/F versus non-Japanese patients. Body weight-adjusted clearance values were generally similar in non-Japanese and Japanese healthy subjects and also in patients with ESRD on hemodialysis.

Evaluation of Drug-Drug Interaction Potential of Enarodustat (JTZ-951) Using a Cytochrome P450 Probe Cocktail.

The drug interaction potential of enarodustat (doses: 25, 50 mg) on the activity of cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4 was evaluated after once-daily administration for 15 days in a phase 1 multiple-ascending-dose study in healthy subjects. Probe substrates specific for the enzymes, i.e., caffeine (CYP1A2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), and midazolam (CYP3A4), were administered orally as a cocktail with (day 15) and without (day -3) enarodustat. Drug interaction was based on geometric mean maximum plasma concentration (Cmax ) and area under the plasma concentration-time curve from the time of dosing to infinity (AUCinf ) ratios (day 15/day -3) for CYP1A2, 2C9, 2C19, 2D6, 3A4, and urinary excretion of dextromethorphan metabolite dextrorphan for CYP2D6. At the 2 enarodustat doses, for caffeine, the geometric mean ratios (range) for Cmax and AUCinf were 0.99-1.06 and 1.61-1.63, respectively. The ratios for peak concentrations and total exposures were 0.98-1.07 and 0.71-1.78 for tolbutamide and omeprazole, respectively. For dextrorphan the Cmax and AUCinf ratios were 0.83-0.90 and 1.02-1.04, respectively. The mean dextrorphan cumulative amount excreted into the urine from the time of dosing to 24 hours values on day -3 and day 15 were 8.25 mg and 8.20 mg at the lower dose, and 9.40 mg and 9.51 mg at the higher dose. The ratios for midazolam Cmax and AUCinf were 1.42-1.63. Overall, there was a lack of enarodustat dose dependency regarding the geometric mean ratios and 90% confidence intervals and urinary excretion of dextrorphan. There were some cases where the 90% confidence intervals at the 2 enarodustat doses were outside the 0.80-1.25 range, but changes in the geometric mean ratios were all <2-fold.

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

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

Treatment of anemia associated with chronic kidney disease with the HIF prolyl hydroxylase inhibitor enarodustat: A review of the evidence.

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

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

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

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

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

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

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

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

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

A highly sensitive and selective UPLC-MS/MS assay for the determination of enarodustat (JTZ-951) in human plasma.

Enarodustat, a potent, orally bioavailable, selective inhibitor of hypoxia inducible factor-Prolyl hydroxylase (HIF-PH), has been approved recently in Japan for the treatment of anemia in patients with chronic kidney disease (CKD). To evaluate the pharmacokinetics of enarodustat, a bioanalytical assay in human plasma was needed for the quantitation of enarodustat for both healthy subjects and patients with CKD. The UPLC-MS/MS method for the quantitation of enarodustat was initially validated in a bioanalytical laboratory in Japan to support clinical studies conducted in Japan, and then was transferred and validated in a bioanalytical laboratory in United States to support clinical studies conducted here. A cross-validation was successfully performed between the two bioanalytical laboratories using both quality control (QC) samples and incurred study samples. Enarodustat was fortified with its isotopically labeled internal standard in a 25 µL plasma aliquot and extracted with protein precipitation. The chromatographic separation was achieved on an Acquity UPLC BEH C18 (1.7 µm, 2.1 × 50 mm) column with gradient elution. The calibration curve range for the assay was 1.00-500 ng/mL. Assay precision, accuracy, linearity, selectivity, sensitivity and analyte stability covering sample storage and analysis were established. No interferences were observed from medications that may be co-administered along with enarodustat. The validated UPLC-MS-MS method at the US bioanalytical laboratory has been successfully applied to eight clinical studies for the determination of enarodustat concentrations in human plasma for both healthy subjects and patients with CKD.

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

INTRODUCTION: Enarodustat (JTZ-951) is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that might be a new therapeutic approach for managing anemia in patients with chronic kidney disease (CKD). We evaluated the efficacy (noninferiority to darbepoetin alfa [DA]) and safety of enarodustat in Japanese anemic patients with CKD not requiring dialysis. METHODS: Erythropoiesis-stimulating agent (ESA)-naïve patients and ESA-treated patients were randomized at a 1:1 ratio to receive enarodustat orally once daily or DA subcutaneously every 2 or 4 weeks for 24 weeks, respectively. Subjects in each arm had dose adjustments every 4 weeks to maintain their hemoglobin (Hb) level within the target range (10 to 12 g/dl). The primary endpoint was the difference in the mean Hb level between arms during the evaluation period defined as weeks 20 to 24 (noninferiority margin: -0.75 g/dl). RESULTS: The mean Hb level during the evaluation period in the enarodustat arm was 10.96 g/dl (95% confidence interval [CI]: 10.84 to 11.07 g/dl) with a difference of 0.09 g/dl (95% CI: -0.07 to 0.26 g/dl) between arms, establishing its noninferiority to DA. Nearly 90% of subjects in both arms maintained a mean Hb level within the target range. Compared with DA, enarodustat was associated with decreased hepcidin and ferritin, and increased total iron-binding capacity. There were no apparent differences in the incidence of adverse events between arms (65.4% [enarodustat], 82.6% [DA]). CONCLUSIONS: The efficacy of enarodustat was comparable to DA in anemic patients with CKD not requiring dialysis. No new safety concerns were identified compared with DA.

Enarodustat to treat anemia in chronic kidney disease.

Anemia is a common complication in patients with chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) are the standard therapy for anemia in CKD. It has been expected that hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibition may have the potential to provide therapeutic benefits over pre-existing ESAs for anemia in CKD. Enarodustat (JTZ-951) is an oral HIF-PH inhibitor. In preclinical studies, enarodustat has been found to increase HIF-alpha proteins, erythropoietin production and erythropoiesis. Enarodustat also shows efficient iron utilization in iron-related parameters during erythropoiesis. Clinical trials have shown that enarodustat improved anemia both in non-dialysis-dependent CKD patients and dialysis patients. The safety results in clinical trials demonstrate that enarodustat is generally well tolerated. On the basis of these results, enarodustat was approved in September 2020 in Japan for the treatment of anemia associated with CKD. This manuscript will review enarodustat, its pharmacological characteristics in preclinical studies, and its efficacy and safety in clinical trials with anemic patients in CKD.

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

INTRODUCTION: Enarodustat (JTZ-951) is a new oral hypoxia-inducible factor-prolyl hydroxylase inhibitor for the treatment of anemia in chronic kidney disease (CKD). We conducted a phase 3 study to compare the efficacy and safety of enarodustat with darbepoetin alfa (DA) in Japanese anemic patients with CKD receiving maintenance hemodialysis. METHODS: Subjects receiving maintenance hemodialysis were randomly assigned at a 1:1 ratio to receive oral enarodustat once daily or intravenous DA every week for 24 weeks with dose adjustment every 4 weeks to maintain hemoglobin (Hb) within a target range (≥10.0 to <12.0 g/dL). The primary efficacy endpoint was difference in mean Hb level between arms during the evaluation period defined as weeks 20-24 (noninferiority margin: -1.0 g/dL). Intravenous iron preparations were prohibited during the screening period and during weeks 0-4. RESULTS: The mean Hb level of each arm during the evaluation period was 10.73 g/dL (95% confidence interval [CI]: 10.56, 10.91) in the enarodustat arm and 10.85 g/dL (95% CI: 10.72, 10.98) in the DA arm. The difference in the mean Hb level between arms was -0.12 g/dL (95% CI: -0.33, 0.10), confirming the noninferiority of enarodustat to DA. The mean Hb level of each arm was maintained within the target range during the treatment period. Increased total iron-binding capacity and serum iron and decreased hepcidin were observed through week 4 in the enarodustat arm albeit after switching from erythropoiesis-stimulating agents. No apparent safety concerns of enarodustat were observed compared with DA. DISCUSSION/CONCLUSION: Enarodustat was noninferior to DA for the treatment of anemia in CKD patients receiving maintenance hemodialysis and was generally well tolerated over 24 weeks.

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.

JTZ-951 (enarodustat), a hypoxia-inducibe factor prolyl hydroxylase inhibitor, stabilizes HIF-α protein and induces erythropoiesis without effects on the function of vascular endothelial growth factor.

JTZ-951 (enarodustat) is an oral hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor. JTZ-951 has inhibitory activities on human HIF-prolyl hydroxylase 1-3, but not on various receptors or enzymes. In Hep3B cells, JTZ-951 increased HIF-1α and HIF-2α protein levels, erythropoietin (EPO) mRNA levels, and EPO production. In normal rats, after a single oral dose of JTZ-951, the hepatic and renal EPO mRNA levels and plasma EPO concentrations were also increased. In 5/6-nephrectomized rats, repeated oral doses of JTZ-951 once daily or intermittent dosing showed the erythropoiesis stimulating effect. The administration of JTZ-951 at a high dose increased plasma vascular endothelial growth factor (VEGF) levels; however, retinal VEGF mRNA levels and the retinal vascular permeability were not changed. Finally, we evaluated the effect of JTZ-951 in a colorectal cancer cell-inoculated mouse model. Although JTZ-951 at a high dose increased the plasma VEGF, it had no effect on tumor growth. In summary, JTZ-951 induces erythropoiesis without affecting VEGF function. Therefore, it is expected that JTZ-951 will be a new oral candidate that increases and maintains hemoglobin concentrations in renal anemia patients.