Simultaneous detection of three hypoxia-inducible factor stabilizers-molidustat, roxadustat, and vadadustat-in multiple keratinized matrices and its application in a doping context.

In a doping case, a top athlete challenged an anti-doping rule violation, involving molidustat. Molidustat is a stabilizing agent of the hypoxia-inducible factor (HIF) recently developed. It is currently undergoing clinical trials for anemia associated with chronic kidney disease. HIF stabilizers are banned at all times by the World Anti-Doping Agency (class S2). Because of their pharmacological proprieties, these new drugs can enhance athletic performance. The athlete's defense wanted to analyze multiple keratinized matrices as they allow long-term investigations. Requests concerning HIF stabilizers are constantly growing. We have therefore developed a liquid chromatography coupled with tandem mass spectrometry method to identify and quantify three molecules of this class: molidustat, vadadustat, and roxadustat. Thirty milligrams of keratinized matrices were incubated in 1 mL of pH 8.4 diammonium hydrogen phosphate buffer for 16 h at 40°C with 1 ng of testosterone-D3, used as internal standard. After extraction with ethyl acetate/diethyl ether (80/20), the organic phase was evaporated, and the dry residue was reconstituted in 30 µL of initial phase. The method was linear from 5 to 1000 pg/mg for the three analytes. Limits of quantification were 2, 0.5, and 5 pg/mg for molidustat, roxadustat, and vadadustat, respectively. The analysis of the athlete's head hair (collected 1 month after the urine test) showed a concentration of molidustat of 135 pg/mg, and his beard hair and his fingernails clippings contained 55 and 40 pg/mg, respectively.

The efficacy and safety of molidustat for anemia in dialysis-dependent and non-dialysis-dependent chronic kidney disease patients: A systematic review and meta-analysis.

Objective: Molidustat is a novel agent investigated for the treatment of anemia in both dialysisdependent (DD) and non-dialysis-dependent (NDD) patients. Its efficacy and safety are still unclear. Methods: We searched five databases to identify randomized controlled trials comparing molidustat to erythropoiesis-stimulating agents (ESAs) or placebo in patients with anemia. Results: Six studies containing 2025 eligible participants were identified. For NDD patients, the change in Hb levels from baseline (ΔHb) was significantly higher for molidustat than for placebo [mean difference (MD) = 1.47 (95 % CI: 1.18 to 1.75), P < 0.00001] and ΔHb was also significantly higher for molidustat than for ESAs [MD = 0.25 (95 % CI 0.09 to 0.40), P = 0.002]. For NDD patients, Δhepcidin was significantly lower for molidustat than for placebo [MD = -20.66 (95 % CI: -31.67 to -9.66), P = 0.0002] and Δhepcidin was also significantly lower for molidustat than for ESAs [MD = -24.51 (95 % CI: -29.12 to -19.90), P < 0.00001]. For NDD patients, Δiron was significantly lower for molidustat than for ESAs [MD = -11.85 (95 % CI: -15.52 to -8.18), P < 0.00001], and ΔTSAT was also significantly lower for molidustat than for ESAs [MD = -5.29 (95 % CI: -6.81 to -3.78), P < 0.00001]. For NDD patients, Δferritin was significantly lower for molidustat than for placebo [MD = -90.01 (95 % CI: -134.77 to -45.25), P < 0.00001]. However, for DD-CKD patients, molidustat showed an effect similar to that of ESAs on increasing the Hb level [MD = -0.18 (95 % CI: -0.47 to 0.11), P = 0.23], Δiron level [MD = 3.78 (95 % CI: -7.21 to 14.76), P = 0.5], Δferritin level [MD = 25.03 (95 % CI: -34.69 to 84.75), P = 0.41], and Δhepcidin level [MD = 1.20 (95 % CI: -4.36 to 6.76), P = 0.67]. For DD-CKD patients, compared with the placebo or ESA group, molidustat showed a significantly higher level on ΔTSAT[MD = 3.88 (95 % CI: 2.10 to 5.65), P < 0.0001] and a slightly increased level on ΔTIBC level [MD = 1.08 (95 % CI: -0.07 to 2.23), P = 0.07]. There was no significant difference in the incidence of severe adverse events (SAEs), death, and cardio-related adverse events between molidustat and the ESAs groups. Conclusions: Moricizine can effectively improves Hb levels in NDD patients and corrects anemia in DD patients without increasing adverse event incidence.

Pharmacodynamic effects of molidustat on erythropoiesis in healthy cats.

BACKGROUND: Inhibition of hypoxia-inducible factor prolyl hydroxylase (HIF-PH) stimulates erythropoiesis in rats, dogs, monkeys, and humans. HYPOTHESIS/OBJECTIVE: Determine if molidustat, a novel HIF-PH inhibitor, stimulates erythropoiesis in healthy cats. ANIMALS: Seventeen healthy adult laboratory cats. METHODS: Randomized, placebo-controlled study. Cats were treated PO once daily with suspensions of 0 (Group 1; n = 6), 5 (Group 2; n = 6), or 10 (Group 3; n = 5) mg/kg of molidustat. Effects on red blood cell parameters, reticulocyte indices and plasma erythropoietin (EPO) concentrations were evaluated. Molidustat treatment was stopped when hematocrit (HCT) exceeded 60%. RESULTS: Compared to placebo, a significant increase in mean HCT was evident starting on Day 14 (Group 2:54.4% vs 40.3%, P < .001, 95% confidence interval [CI] for the difference [8.95-19.28]; Group 3:61.2% vs 40.3%, P < .001, 95% CI [15.48-26.43]) and remained significantly higher for the entire treatment period. In molidustat-treated groups, HCT exceeded 60% on Day 21 (Group 2) and Day 14 (Group 3). Mean HCT in molidustat-treated cats returned to within the reference range (29%-45%) after Day 56 and was numerically comparable to placebo from Day 70 onwards. Red blood cell count and hemoglobin concentrations followed a similar pattern as HCT. Mean EPO concentrations significantly increased after molidustat administration on all assessment days. Molidustat treatments were well tolerated. CONCLUSIONS AND CLINICAL IMPORTANCE: Marked erythropoietic effects were identified after daily administration of molidustat to healthy cats and additional studies are warranted to evaluate the effects in anemic cats.

Treatment satisfaction with molidustat in CKD-related anemia in non-dialysis patients: a post-hoc analysis of two clinical trials.

BACKGROUND: Erythropoiesis-stimulating agents (ESAs) are the standard treatment for patients with renal anemia to increase hemoglobin (Hb) levels and reduce the need for blood transfusions. However, treatments targeting high Hb levels require high doses of ESAs administered intravenously, which is associated with an elevated risk of adverse cardiovascular events. Furthermore, there have been some problems such as hemoglobin variability and low achievement of target hemoglobin due to the shorter half-lives of ESAs. Consequently, erythropoietin-promoting medications, such as hypoxia-inducible factor-prolyl hydroxylase (HIF-PH) inhibitors, have been developed. This study aimed to evaluate changes in the Treatment Satisfaction Questionnaire for Medicine version II (TSQM-II) domain scores relative to baseline in each trial, to assess patient satisfaction with molidustat versus darbepoetin alfa. METHODS: This post-hoc analysis of two clinical trials compared treatment satisfaction with an HIF-PH inhibitor, molidustat, versus a standard ESA, darbepoetin alfa, as part of therapy in patients with non-dialysis chronic kidney disease (CKD) and renal anemia. RESULTS: Exploratory outcome data using the TSQM-II showed that both arms in both trials had enhanced treatment satisfaction over the course of the study period, as well as improvements in most TSQM-II domains at week 24 of treatment. Molidustat was associated with convenience domain scores at multiple time points depending on the trial. More patients were highly satisfied with the convenience of molidustat than that of darbepoetin alfa. Patients treated with molidustat had increased global satisfaction domain scores compared with those treated with darbepoetin alfa; however, the differences in global satisfaction domain scores were not significant. CONCLUSION: These patient-reported satisfaction outcomes support the use of molidustat as a patient-centered treatment option for CKD-related anemia. REGISTRATION OF CLINICAL TRIALS: ClinicalTrials.gov Identifier: NCT03350321 (November 22, 2017). CLINICALTRIALS: gov Identifier: NCT03350347 (November 22, 2017).

HIF-PH Encoded by EGLN1 Is a Potential Therapeutic Target for Chronic Lymphocytic Leukemia.

Owing to the recent emergence of drug resistance to Bruton's tyrosine kinase inhibitors (BTK) in chronic lymphocytic leukemia (CLL) treatment, it is crucial to identify alternative therapeutic targets. Therefore, we aimed to identify therapeutic options for CLL besides BTK. We identified that HIF1A expression was higher in CLL patients than in controls, which may suggest good prognosis. We used a lentiviral knockdown of EGLN1 (encoding hypoxia-inducible factor prolyl hydroxylase [HIF-PH]) and found that the growth of MEC-1 cells slowed in the knockdown group. Treatment of CLL cell lines MEC-1 and HG3 with the HIF-PH inhibitor molidustat showed that molidustat could induce apoptosis in a concentration-dependent manner in CLL cells and had low cytotoxicity at this concentration. CXCR4, HIF1A, SLC2AI, and VEGF, the downstream molecules of the HIF pathway, were upregulated after molidustat treatment. Western blotting results indicated that molidustat increased HIF1A expression in CLL cell lines and cells from CLL patients, and sequencing/quantitative PCR analysis demonstrated that the ribosome biogenesis pathway was inhibited in MEC-1 cells after molidustat treatment. We further identified synergistic cytotoxicity of molidustat in combination with ibrutinib on the MEC-1 and HG3 cell lines at certain concentrations. Therefore, molidustat is a potential therapeutic option for CLL.

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

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

EPO synthesis induced by HIF-PHD inhibition is dependent on myofibroblast transdifferentiation and colocalizes with non-injured nephron segments in murine kidney fibrosis.

AIM: Erythropoietin (EPO) is regulated by hypoxia-inducible factor (HIF)-2. In the kidney, it is produced by cortico-medullary perivascular interstitial cells, which transdifferentiate into collagen-producing myofibroblasts in response to injury. Inhibitors of prolyl hydroxylase domain (PHD) dioxygenases (HIF-PHIs) activate HIF-2 and stimulate kidney and liver EPO synthesis in patients with anemia of chronic kidney disease (CKD). We examined whether HIF-PHIs can reactivate EPO synthesis in interstitial cells that have undergone myofibroblast transdifferentiation in established kidney fibrosis. METHODS: We investigated Epo transcription in myofibroblasts and characterized the histological distribution of kidney Epo transcripts by RNA in situ hybridization combined with immunofluorescence in mice with adenine nephropathy (AN) treated with HIF-PHI molidustat.  Lectin absorption chromatography was used to assess liver-derived EPO.  In addition, we examined kidney Epo transcription in Phd2 knockout mice with obstructive nephropathy. RESULTS: In AN, molidustat-induced Epo transcripts were not found in areas of fibrosis and did not colocalize with interstitial cells that expressed α-smooth muscle actin, a marker of myofibroblast transdifferentiation. Epo transcription was associated with megalin-expressing, kidney injury molecule 1-negative nephron segments and contingent on residual renal function. Liver-derived EPO did not contribute to serum EPO in molidustat-treated mice. Epo transcription was not associated with myofibroblasts in Phd2 knockout mice with obstructive nephropathy. CONCLUSIONS: Our studies suggest that HIF-PHIs do not reactivate Epo transcription in interstitial myofibroblasts and that their efficacy in inducing kidney EPO in CKD is dependent on the degree of myofibroblast formation, the preservation of renal parenchyma and the level of residual renal function.

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.

Molidustat for Japanese Patients With Renal Anemia Receiving Dialysis.

INTRODUCTION: Molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor for renal anemia treatment, was evaluated in 5 phase 3 studies (MIYABI program). We report the results of the MIYABI hemodialysis-maintenance study. METHODS: This 52-week, randomized, double-blinded, double-dummy study compared the efficacy and safety of molidustat and darbepoetin in Japanese patients receiving hemodialysis and erythropoiesis-stimulating agents. Molidustat (starting dose: 75 mg/day) and darbepoetin were titrated to maintain hemoglobin (Hb) levels in the target range (≥10.0 and <12.0 g/dl). Primary outcomes were mean Hb level during the evaluation period (weeks 33-36) and its change from baseline. Safety outcomes included adverse events. RESULTS: Overall, 229 patients were randomized (molidustat, n = 153; darbepoetin, n = 76). Baseline characteristics were well balanced. Mean baseline Hb level was 10.8 g/dl. Mean (95% confidence interval [CI]) for mean Hb levels during the evaluation period were within the target range in both groups (molidustat: 10.63 [10.42-10.84] g/dl; darbepoetin: 10.77 [10.59-10.95] g/dl). Least-squares mean (95% CI) change in mean Hb level during the evaluation period from baseline was -0.14 (-0.37 to 0.09) g/dl for molidustat and -0.07 (-0.30 to 0.16) g/dl for darbepoetin; molidustat was noninferior to darbepoetin (least-squares mean difference [95% CI] [molidustat-darbepoetin]: -0.13 [-0.46 to 0.19] g/dl), based on a noninferiority margin of 1.0 g/dl. In line with published literature, and as expected in this patient population, most participants had ≥1 treatment-emergent adverse event. CONCLUSION: Molidustat maintained Hb levels throughout the trial in patients receiving dialysis and previously treated with erythropoiesis-stimulating agents, and was noninferior to darbepoetin.

Molidustat for Renal Anemia in Nondialysis Patients Previously Treated with Erythropoiesis-Stimulating Agents: A Randomized, Open-Label, Phase 3 Study.

INTRODUCTION: Erythropoiesis-stimulating agents (ESAs) are the current standard of care for anemia due to chronic kidney disease (CKD) in patients not undergoing dialysis. Molidustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, is being investigated as an alternative treatment for renal anemia. Molidustat was evaluated in five phase 3 studies, the molidustat once daily improves renal anemia by inducing erythropoietin (MIYABI) program. The present study investigated the safety and efficacy of molidustat in Japanese patients with renal anemia not undergoing dialysis and previously treated with ESAs. METHODS: This was a 52-week, active-controlled, randomized (1:1), open-label, parallel-group, multicenter, phase 3 study in Japanese patients with anemia due to CKD (stages 3-5). Molidustat was initiated at 25 mg or 50 mg once daily according to previous ESA dose. The ESA darbepoetin alfa (darbepoetin) was initiated at a starting dose in accordance with the previous ESA dose and injected subcutaneously once every 2 or 4 weeks. Doses were regularly titrated to maintain hemoglobin (Hb) levels in the target range of 11.0-13.0 g/dL. The primary efficacy outcome was the mean Hb level and its change from baseline during the evaluation period (weeks 30-36). The safety outcomes included evaluation of all adverse events. RESULTS: In total, 164 patients were randomized to receive molidustat (n = 82) or darbepoetin (n = 82). Baseline characteristics were well balanced. Mean (standard deviation) Hb levels at baseline were 11.31 (0.68) g/dL for molidustat and 11.27 (0.64) g/dL for darbepoetin. The mean (95% confidence interval [CI]) for mean Hb levels during the evaluation period for molidustat (11.67 [11.48-11.85] g/dL) and darbepoetin (11.53 [11.31-11.74] g/dL) was within the target range. Based on a noninferiority margin of 1.0 g/dL, molidustat was noninferior to darbepoetin regarding the change in mean Hb level during the evaluation period from baseline, with a least squares mean (95% CI) difference (molidustat-darbepoetin) of 0.13 (-0.15, 0.40) g/dL. The proportion of patients who reported at least 1 treatment-emergent adverse event (TEAE) was 92.7% for molidustat and 96.3% for darbepoetin. TEAEs leading to death were reported in 2 patients (2.4%) in the molidustat group and none in the darbepoetin group; serious TEAEs were reported in 32.9% and 26.8% of patients, respectively. DISCUSSION/CONCLUSION: Molidustat was noninferior to darbepoetin and maintained Hb levels in the prespecified target range in patients with renal anemia not undergoing dialysis and previously treated with ESA. Molidustat was well tolerated, and no new safety signal was observed.

Efficacy and Safety of Molidustat for Anemia in ESA-Naive Nondialysis Patients: A Randomized, Phase 3 Trial.

INTRODUCTION: Molidustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that predominantly induces renal production of erythropoietin (EPO). Molidustat was evaluated for the treatment of anemia associated with chronic kidney disease (CKD) in the "Molidustat Once Daily Improves Renal Anemia by Inducing EPO" (MIYABI) program, which comprises 5 phase 3 clinical trials. The present MIYABI Non-Dialysis Correction (ND-C) study investigated the efficacy and safety of molidustat in Japanese patients with renal anemia who were not undergoing dialysis and were not receiving erythropoiesis-stimulating agent (ESA) treatment. METHODS: This was a 52-week, randomized (1:1), open-label, active-control, parallel-group, multicenter, phase 3 study in Japanese patients with renal anemia associated with CKD (stages 3-5). Molidustat or the ESA darbepoetin alfa (hereinafter referred to as darbepoetin) were initiated at 25 mg once daily or 30 µg every 2 weeks, respectively, and doses were regularly titrated to correct and to maintain hemoglobin (Hb) levels in the target range of ≥11.0 g/dL and <13.0 g/dL. The primary efficacy outcome was the mean Hb level and its change from baseline during the evaluation period (weeks 30-36). The safety outcomes included evaluation of all adverse events. RESULTS: In total, 162 patients were randomized to receive molidustat (n = 82) or darbepoetin (n = 80). Baseline characteristics were generally well balanced between treatment groups. The mean (standard deviation) Hb levels at baseline were 9.84 (0.64) g/dL for molidustat and 10.00 (0.61) g/dL for darbepoetin. The mean (95% confidence interval [CI]) for mean Hb levels during the evaluation period for molidustat (11.28 [11.07, 11.50] g/dL) and darbepoetin (11.70 [11.50, 11.90] g/dL) was within the target range. Based on a noninferiority margin of 1.0 g/dL, molidustat was noninferior to darbepoetin in the change in mean Hb level during the evaluation period from baseline; the least-squares mean (95% CI) difference (molidustat-darbepoetin) was -0.38 (-0.67, -0.08) g/dL. The proportion of patients who reported at least 1 treatment-emergent adverse event (TEAE) was 93.9% for molidustat and 93.7% for darbepoetin. Most TEAEs were mild (54.9% for molidustat and 63.3% for darbepoetin) or moderate (22.0% for molidustat and 22.8% for darbepoetin) in intensity. There were 3 deaths in the molidustat group and 1 in the darbepoetin group. DISCUSSION/CONCLUSION: In the MIYABI ND-C study, molidustat appeared to be an efficacious and generally well-tolerated alternative to darbepoetin for the treatment of renal anemia in Japanese patients who were not undergoing dialysis and were not receiving ESA treatment.

Stabilization of Hypoxia-Inducible Factor Promotes Antimicrobial Activity of Human Macrophages Against Mycobacterium tuberculosis.

Hypoxia-inducible factor (HIF) is a key oxygen sensor that controls gene expression patterns to adapt cellular metabolism to hypoxia. Pharmacological inhibition of prolyl-hydroxylases stabilizes HIFs and mimics hypoxia, leading to increased expression of more than 300 genes. Whether the genetic program initialized by HIFs affects immune responses against microbial pathogens, is not well studied. Recently we showed that hypoxia enhances antimicrobial activity against Mycobacterium tuberculosis (Mtb) in human macrophages. The objective of this study was to evaluate whether the oxygen sensor HIF is involved in hypoxia-mediated antimycobacterial activity. Treatment of Mtb-infected macrophages with the prolyl-hydroxylase inhibitor Molidustat reduced the release of TNFα and IL-10, two key cytokines involved in the immune response in tuberculosis. Molidustat also interferes with the p38 MAP kinase pathway. HIF-stabilization by Molidustat also induced the upregulation of the Vitamin D receptor and human ß defensin 2, which define an antimicrobial effector pathway in human macrophages. Consequently, these immunological effects resulted in reduced proliferation of virulent Mtb in human macrophages. Therefore, HIFs may be attractive new candidates for host-directed therapies against infectious diseases caused by intracellular bacteria, including tuberculosis.

Structural Basis of Prolyl Hydroxylase Domain Inhibition by Molidustat.

Human prolyl-hydroxylases (PHDs) are hypoxia-sensing 2-oxoglutarate (2OG) oxygenases, catalysis by which suppresses the transcription of hypoxia-inducible factor target genes. PHD inhibition enables the treatment of anaemia/ischaemia-related disease. The PHD inhibitor Molidustat is approved for the treatment of renal anaemia; it differs from other approved/late-stage PHD inhibitors in lacking a glycinamide side chain. The first reported crystal structures of Molidustat and IOX4 (a brain-penetrating derivative) complexed with PHD2 reveal how their contiguous triazole, pyrazolone and pyrimidine/pyridine rings bind at the active site. The inhibitors bind to the active-site metal in a bidentate manner through their pyrazolone and pyrimidine nitrogens, with the triazole π-π-stacking with Tyr303 in the 2OG binding pocket. Comparison of the new structures with other PHD inhibitor complexes reveals differences in the conformations of Tyr303, Tyr310, and a mobile loop linking ß2-ß3, which are involved in dynamic substrate binding/product release.

Pharmacological HIF-PHD inhibition reduces renovascular resistance and increases glomerular filtration by stimulating nitric oxide generation.

AIM: Hypoxia-inducible factors (HIFs) are O2 -sensitive transcription factors that regulate multiple biological processes which are essential for cellular adaptation to hypoxia. Small molecule inhibitors of HIF-prolyl hydroxylase domain (PHD) dioxygenases (HIF-PHIs) activate HIF-dependent transcriptional programs and have broad clinical potential. HIF-PHIs are currently in global late-stage clinical development for the treatment of anaemia associated with chronic kidney disease. Although the effects of hypoxia on renal haemodynamics and function have been studied in animal models and in humans living at high altitude, the effects of pharmacological HIF activation on renal haemodynamics, O2 metabolism and metabolic efficiency are not well understood. METHODS: Using a cross-sectional study design, we investigated renal haemodynamics, O2 metabolism, gene expression and NO production in healthy rats treated with different doses of HIF-PHIs roxadustat or molidustat compared to vehicle control. RESULTS: Systemic administration of roxadustat or molidustat resulted in a dose-dependent reduction in renovascular resistance (RVR). This was associated with increased glomerular filtration rate (GFR), urine flow and tubular sodium transport rate (TNa ). Although both total O2 delivery and TNa were increased, more O2 was extracted per transported sodium in rats treated with high-doses of HIF-PHIs, suggesting a reduction in metabolic efficiency. Changes in RVR and GFR were associated with increased nitric oxide (NO) generation and substantially suppressed by pharmacological inhibition of NO synthesis. CONCLUSIONS: Our data provide mechanistic insights into dose-dependent effects of short-term pharmacological HIF activation on renal haemodynamics, glomerular filtration and O2 metabolism and identify NO as a major mediator of these effects.

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.

The HIF-PHI BAY 85-3934 (Molidustat) Improves Anemia and Is Associated With Reduced Levels of Circulating FGF23 in a CKD Mouse Model.

Fibroblast growth factor-23 (FGF23) is a critical factor in chronic kidney disease (CKD), with elevated levels causing alterations in mineral metabolism and increased odds for mortality. Patients with CKD develop anemia as the kidneys progressively lose the ability to produce erythropoietin (EPO). Anemia is a potent driver of FGF23 secretion; therefore, a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) currently in clinical trials to elevate endogenous EPO to resolve anemia was tested for effects on iron utilization and FGF23-related parameters in a CKD mouse model. Mice were fed either a casein control diet or an adenine-containing diet to induce CKD. The CKD mice had markedly elevated iFGF23 and blood urea nitrogen (BUN), hyperphosphatemia, and anemia. Cohorts of mice were then treated with a patient-equivalent dose of BAY 85-3934 (BAY; Molidustat), which elevated EPO and completely resolved aberrant complete blood counts (CBCs) in the CKD mice. iFGF23 was elevated in vehicle-treated CKD mice (120-fold), whereas circulating iFGF23 was significantly attenuated (>60%) in the BAY-treated CKD mice. The BAY-treated mice with CKD also had reduced BUN, but there was no effect on renal vitamin D metabolic enzyme expression. Consistent with increased EPO, bone marrow Erfe, Transferrin receptor (Tfrc), and EpoR mRNAs were increased in BAY-treated CKD mice, and in vitro hypoxic marrow cultures increased FGF23 with direct EPO treatment. Liver Bmp-6 and hepcidin expression were downregulated in all BAY-treated groups. Femur trabecular parameters and cortical porosity were not worsened with BAY administration. In vitro, differentiated osteocyte-like cells exposed to an iron chelator to simulate iron depletion/hypoxia increased FGF23; repletion with holo-transferrin completely suppressed FGF23 and normalized Tfrc1. Collectively, these results support that resolving anemia using a HIF-PHI during CKD was associated with lower BUN and reduced FGF23, potentially through direct restoration of iron utilization, thus providing modifiable outcomes beyond improving anemia for this patient population. © 2021 American Society for Bone and Mineral Research (ASBMR).

Drug-drug interaction of atazanavir on UGT1A1-mediated glucuronidation of molidustat in human.

Molidustat is an oral inhibitor of hypoxia-inducible factor (HIF) prolyl-hydroxylase enhancing the erythropoietin (EPO) response to HIF; it is in clinical development for the treatment of anaemia related to chronic kidney disease. The predominant role of glucuronidation for molidustat clearance (formation of N-glucuronide metabolite M1) and subsequent renal excretion was confirmed in a human mass balance study, with about 85% of the drug being excreted as M1 in urine. The inhibitory effects of 176 drugs and xenobiotics from various compound classes on the UGT-mediated glucuronidation of molidustat in human liver microsomes (HLMs) were investigated. Based on preclinical findings, glucuronidation of molidustat was predominantly mediated by the 5'-diphospho-glucuronosyltransferase (UGT) isoform UGT1A1. Therefore, atazanavir, which is a potent inhibitor of UGT1A1, was chosen for the evaluation of pharmacokinetics and EPO release following a single oral dose of 25 mg molidustat. Molidustat exposure increased about twofold upon coadministration with atazanavir when considering area under plasma concentration-time curve from zero to infinity (AUC) and maximum plasma concentration (Cmax ). Baseline-corrected increase of EPO was 14% and 34% for Cmax and AUC (calculated over 24 hours), respectively. Coadministration of molidustat and atazanavir was well tolerated.

Effects of oral iron and calcium supplement on the pharmacokinetics and pharmacodynamics of molidustat: an oral HIF-PH inhibitor for the treatment of renal anaemia.

PURPOSE: The present studies assessed the drug-drug interaction of molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, with iron and calcium supplements, which are common medications in patients with anaemia due to chronic kidney disease (CKD). METHODS: Forty-two healthy men received molidustat alone (fasted or fed) or combined with oral iron(II) or calcium(II), given immediately before or between 4 h before and 1 h after molidustat in three randomized, open-label, crossover studies (12-15 participants per study). Molidustat AUC and Cmax were assessed as the main pharmacokinetic parameters, and endogenous erythropoietin (EPO) was measured to evaluate pharmacodynamics. RESULTS: Depending on prandial state, concomitant intake of iron(II) reduced molidustat AUC and Cmax by 50-75% and 46-84%, respectively, and EPO AUC(0-24) and Cmax by 31-44% and 36-48%, respectively. The influence of iron(II) declined with increasing the time interval to the intake of molidustat, with reductions in molidustat AUC and Cmax of 9% and 10%, respectively, when iron(II) intake occurred 4 h before molidustat. Accordingly, effects on endogenous EPO were less pronounced with increased time separation between oral iron(II) and molidustat intake. Calcium(II) reduced molidustat AUC and Cmax by 15% and 47%, respectively, without influence on EPO response. All treatments were well tolerated. CONCLUSIONS: In contrast to concomitant oral intake of calcium, the effect of oral iron supplements on molidustat pharmacokinetics and pharmacodynamics should be considered, and the two agents should be administered with an appropriate time separation.

Mannose Binding Lectin Is Hydroxylated by Collagen Prolyl-4-hydroxylase and Inhibited by Some PHD Inhibitors.

Background: Mannose-binding lectin (MBL) is an important component of innate immune defense. MBL undergoes oligomerization to generate high mol weight (HMW) forms which act as pattern recognition molecules to detect and opsonize various microorganisms. Several post-translational modifications including prolyl hydroxylation are known to affect the oligomerization of MBL. Yet, the enzyme(s) which hydroxylate proline in the collagen-like domain residues have not been identified and the significance of prolyl hydroxylation is incompletely understood. Methods: To investigate post-translational modifications of MBL, we stably expressed Myc-DDK tagged MBL in HEK293S cells. We used pharmacologic and genetic inhibition of 2-oxoglutarate-dependent dioxygenases (2OGDD) to identify the enzyme required for prolyl hydroxylation of MBL. We performed mass spectrometry to determine the effects of various inhibitors on MBL modifications. Results: Secretion of HMW MBL was impaired by inhibitors of the superfamily of 2OGDD, and was dependent on prolyl-4-hydroxylase subunit α1. Roxadustat and vadadustat, but not molidustat, led to significant suppression of hydroxylation and secretion of HMW forms of MBL. Conclusions: These data suggest that prolyl hydroxylation in the collagen-like domain of MBL is mediated by collagen prolyl-4-hydroxylase. Reduced MBL activity is likely to be an off-target effect of some, but not all, prolyl hydroxylase domain (PHD) inhibitors. There may be advantages in selective PHD inhibitors that would not interfere with MBL production.