Roxadustat (FG-4592) Versus Epoetin Alfa for Anemia in Patients Receiving Maintenance Hemodialysis: A Phase 2, Randomized, 6- to 19-Week, Open-Label, Active-Comparator, Dose-Ranging, Safety and Exploratory Efficacy Study

Cardiovascular and renal safety outcomes of hypoxia-inducible factor prolyl-hydroxylase inhibitor roxadustat for anemia patients with chronic kidney disease: a systematic review and meta-analysis

This systematic review and meta-analysis were conducted to evaluate the cardiac and kidney-related adverse effects of roxadustat for the treatment of anemia in CKD patients. 18 trials with a total of 8806 participants were identified for analysis. We employed a fixed-effects model for analysis. The pooled result revealed no significant difference in the risk of occurrence of cardiac disorders when comparing CKD patients receiving roxadustat with the placebo (RR = 1.049; CI [0.918 to 1.200]) or ESA (RR = 1.066; CI [0.919 to 1.235]), in both dialysis-dependent (DD) (RR = 1.094; CI [0.925 to 1.293]) or non-dialysis-dependent (NDD) (RR = 1.036; CI [0.916 to 1.171]) CKD patients. No significant difference was observed in the risk of kidney-related adverse events when comparing roxadustat with the placebo (RR = 1.088; CI [0.980 to 1.209]) or ESA (RR = 0.968; CI [0.831 to 1.152]), in DD (RR = 2.649; CI [0.201 to 34.981]) or NDD (RR = 1.053; CI [0.965 to 1.149]) CKD patients. A high risk of hyperkalemia was observed in the roxadustat group in DD (RR = 0.939; CI [0.898 to 0.981]). Incidence of hypertension was higher in the roxadustat for NDD patients (RR = 1.198; CI [1.042 to 1.377]), or compared to the placebo (RR = 1.374; CI [1.153 to 1.638]). In summary, the risk of cardiac or kidney-related events observed in the roxadustat was not significantly increase whether in DD or NDD patients. However, attention must be paid to the occurrence of hyperkalemia for DD patients and hypertension in NDD patients using roxadustat.

A spotlight on using HIF-PH inhibitors in renal anemia

INTRODUCTION

Erythropoiesis-stimulating agents (ESAs) together with iron supplementation had been the standard treatment for anemia in chronic kidney disease (CKD) for the past decades. Recently, hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) have attracted attention as a novel treatment option.

AREAS COVERED

This review summarizes the effectiveness and the safety of HIF-PHIs based on previous clinical trials and discusses points to consider for their clinical use.

EXPERT OPINION

The results from clinical trials demonstrate that HIF-PHIs are non-inferior to ESAs in terms of the efficacy to maintain or improve blood hemoglobin levels. However, concerns about adverse events including cardiovascular outcomes, thrombotic events, and tumor progression have prevented HIF-PHIs from being widely approved for clinical use. Also, long-term safety has not been demonstrated yet. Practically, HIF-PHIs should be used with caution in patients with a history of thrombosis or active malignancy. Patients without them may be preferable for HIF-PHIs if those are bothered with regular injections of ESAs or are hyporesponsive to ESAs without obvious reasons, provided that the drugs were approved in the country. Even so, clinicians must take caution for signs of adverse events such as heart failure after prescribing the drugs.

Erythropoiesis-stimulating agent hyporesponsiveness was associated with worse survival of hemodialysis patients independent of the serum ferritin level

INTRODUCTION

Ferritin level and erythropoiesis-stimulating agent (ESA) responsiveness are each associated with hemodialysis patient survival. We assessed interrelationships between these two vs. survival.

METHODS

Patients in the Japan Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-2018) were included. All-cause mortality associations were assessed with progressive adjustment to evaluate covariate influence.

RESULTS

During follow-up (median 2.6 years), 773 of 5154 patients died. After covariate adjustment, the mortality hazard ratio (HR) was 0.99 (95% CI: 0.81, 1.20) for low serum ferritin and 1.12 (CI: 0.89, 1.41) for high serum ferritin. By contrast, mortality risk with elevated ESA resistance index (ERI) persisted after covariate adjustment (HR 1.44, CI [1.17-1.78]). The serum ferritin and ERI interaction was not significant; p > 0.96 across all models.

CONCLUSIONS

Japanese hemodialysis patients with high ERI experienced worse survival independent of serum ferritin levels, highlighting the importance of identifying and mitigating ESA hyporesponsiveness among dialysis patients.

Short-term effect of low-dose roxadustat combined with erythropoiesis-stimulating agent treatment for erythropoietin-resistant anemia in patients undergoing maintenance hemodialysis

Background

Erythropoietin resistance is present in some patients with chronic kidney disease, especially in those undergoing hemodialysis, and is often treated using roxadustat rather than iron supplements and erythropoiesis-stimulating agents (ESAs). However, some patients cannot afford full doses of roxadustat. This retrospective study investigated the efficacy of low-dose roxadustat combined with recombinant human erythropoietin (rhuEPO) therapy in 39 patients with erythropoietin-resistant renal anemia undergoing maintenance hemodialysis (3-4 sessions/week).

Methods

The ability of the combination of low-dose roxadustat and rhuEPO to increase the hemoglobin concentration over 12 weeks was assessed. Markers of iron metabolism were evaluated. Eligible adults received 50-60% of the recommended dose of roxadustat and higher doses of rhuEPO.

Results

The mean hemoglobin level increased from 77.67 ± 11.18 g/dL to 92.0 ± 8.35 g/dL after treatment, and the hemoglobin response rate increased to 72%. The mean hematocrit level significantly increased from 24.26 ± 3.99% to 30.04 ± 3.69%. The soluble transferrin receptor level increased (27.29 ± 13.60 mg/L to 38.09 ± 12.78 mg/L), while the total iron binding capacity (49.22 ± 11.29 mg/L to 43.91 ± 12.88 mg/L) and ferritin level (171.05 ± 54.75 ng/mL to 140.83 ± 42.03 ng/mL) decreased.

Conclusion

Therefore, in patients with ESA-resistant anemia who are undergoing hemodialysis, the combination of low-dose roxadustat and rhuEPO effectively improves renal anemia and iron metabolism.

Recent Advances and Therapeutic Implications of 2-Oxoglutarate-Dependent Dioxygenases in Ischemic Stroke

Ischemic stroke is a common disease with a high disability rate and mortality, which brings heavy pressure on families and medical insurance. Nowadays, the golden treatments for ischemic stroke in the acute phase mainly include endovascular therapy and intravenous thrombolysis. Some drugs are used to alleviate brain injury in patients with ischemic stroke, such as edaravone and 3-n-butylphthalide. However, no effective neuroprotective drug for ischemic stroke has been acknowledged. 2-Oxoglutarate-dependent dioxygenases (2OGDDs) are conserved and common dioxygenases whose activities depend on O2, Fe2+, and 2OG. Most 2OGDDs are expressed in the brain and are essential for the development and functions of the brain. Therefore, 2OGDDs likely play essential roles in ischemic brain injury. In this review, we briefly elucidate the functions of most 2OGDDs, particularly the effects of regulations of 2OGDDs on various cells in different phases after ischemic stroke. It would also provide promising potential therapeutic targets and directions of drug development for protecting the brain against ischemic injury and improving outcomes of ischemic stroke.

Assessment of the safety of Roxadustat for cardiovascular events in chronic kidney disease-related anemia using meta-analysis and bioinformatics

Objective

This study compares the cardiovascular risk in anemic chronic kidney disease patients treated with Roxadustat versus erythropoietin stimulating agents (ESAs). It also explores the cardiovascular impact of Roxadustat.

Methods

We searched PubMed, EMBASE, Cochrane, Scopus, and Web of Science databases up to 13 August 2023, using terms such as "ESA," "Roxadustat," "MACE," "stroke," "death," "myocardial infarction," and "heart failure." Two researchers independently selected and extracted data based on predefined criteria. We assessed the risk of bias with the Cochrane tool and analyzed statistical heterogeneity using the Q and I2 tests. We conducted subgroup analyses by geographical region and performed data analysis with Stata 14.0 and RevMan 5.4 software. Data were sourced from the NCBI database by filtering for "Roxadustat" and "human," and differentially expressed genes were identified using R software, setting the significance at p < 0.01 and a 2-fold logFC, followed by GO enrichment analysis, KEGG pathway analysis, and protein interaction network analysis.

Results

A total of 15 articles encompassing 1,43,065 patients were analyzed, including 1,38,739 patients treated with ESA and 4,326 patients treated with Roxadustat. In the overall population meta-analysis, the incidences of Major Adverse Cardiovascular Events (MACE), death, and heart failure (HF) were 13%, 8%, and 4% in the Roxadustat group, compared to 17%, 12%, and 6% in the ESA group, respectively, with P-values greater than 0.05. In the subgroup analysis, the incidences were 13%, 11%, and 4% for the Roxadustat group versus 17%, 15%, and 5% for the ESA group, also with p-values greater than 0.05. Bioinformatics analysis identified 59 differentially expressed genes, mainly involved in the inflammatory response. GO enrichment analysis revealed that these genes are primarily related to integrin binding. The main pathways identified were the TNF signaling pathway, NF-κB signaling pathway, and lipid metabolism related to atherosclerosis. The protein interaction network highlighted IL1B, CXCL8, ICAM1, CCL2, and CCL5 as the top five significantly different genes, all involved in the inflammatory response and downregulated by Roxadustat, suggesting a potential role in reducing inflammation.

Conclusion

The meta-analysis suggests that the use of Roxadustat and ESA in treating anemia associated with chronic kidney disease does not significantly alter the likelihood of cardiovascular events in the overall and American populations. However, Roxadustat exhibited a safer profile with respect to MACE, death, and heart failure. The bioinformatics findings suggest that Roxadustat may influence integrin adhesion and affect the TNF and NF-κB signaling pathways, along with lipid and atherosclerosis pathways, potentially reducing inflammation.

Association between roxadustat use and suppression of thyroid function: a systematic review and meta-analysis

BACKGROUND

Based on several case reports and observational studies, there is a growing concern regarding the potential association between roxadustat, a hypoxia-inducible factor prolyl-hydroxylase inhibitor, and suppression of thyroid function. In this systematic review and meta-analysis (PROSPERO: CRD42023471516), we aimed to evaluate the relationship between roxadustat use and suppression of thyroid function.

METHODS

We conducted a comprehensive search of MEDLINE via PubMed, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials databases using the search term "roxadustat" to identify all relevant studies. The study population comprised adults with renal anemia who participated in a randomized controlled trial or observational study, with roxadustat as the intervention and a placebo or erythropoiesis-stimulating agent (ESA) as the comparator. The primary outcome was suppression of thyroid function and the secondary outcome was hypothyroidism. A meta-analysis was conducted using the DerSimonian-Laird random effects model based on the size of the intention-to-treat population, and the odds ratio (OR) and 95% confidence interval (CI) were calculated. Two reviewers independently screened the articles, extracted data, and assessed studies using the ROBINS-I tool.

RESULTS

Of the six studies eligible for inclusion, a meta-analysis was performed using data from two observational studies comparing roxadustat and ESA. The meta-analysis showed that the incidence of suppression of thyroid function was significantly higher with roxadustat use than with ESA use (OR: 6.45; 95% CI: 3.39-12.27; I2 = 12%). Compared with ESA, roxadustat seemed to potentially increase the risk for suppression of thyroid function in patients with renal anemia.

CONCLUSIONS

Our findings highlighted the importance of monitoring thyroid function in patients treated with roxadustat. The results of this review may enhance the safety of using roxadustat to treat renal anemia through advance recognition of the risk for suppression of thyroid function.

Anaemia in CKD-treatment standard

Anaemia is one of the most common complications of chronic kidney disease (CKD), having a significant impact on quality of life, and is also associated with a number of adverse clinical outcomes. Its pathogenesis is multifactorial, caused largely by an inadequate production of erythropoietin from the diseased kidneys, with iron deficiency, inflammation, shortened red cell lifespan and enhanced blood loss also being contributory factors. The management of this condition was transformed in the late 1980s by the advent of recombinant human erythropoietin (epoetin), and treatment paradigms have developed over the last three decades, largely focusing on a combination of epoetin or its analogues (erythropoiesis-stimulating agents; ESAs) along with iron supplementation, often administered intravenously due to increased hepcidin levels limiting iron absorption from the gut. Indeed, in patients with early CKD and iron deficiency, iron per se may be sufficient to improve the anaemia, delaying the need for ESA therapy. Other causes of anaemia should be excluded and corrected (if possible) before resorting to treatment with ESAs and iron. More recently, the hypoxia-inducible factor-prolyl hydroxylase inhibitors have entered the therapeutic arena; these are orally active agents that upregulate endogenous erythropoietin production as well as a number of iron-regulatory genes which may also enhance erythropoiesis. The latter drugs are highly efficacious, and may have advantages in inflammatory conditions causing resistance to conventional ESA therapy, but concerns exist regarding their safety, particularly in the longer term. This article reviews the current standards of treatment, as well as recent novel developments in the management of anaemia in CKD.

Consensus commentary and position of the Italian Society of Nephrology on KDIGO controversies conference on novel anemia therapies in chronic kidney disease

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are new drugs developed for the treatment of anemia associated with chronic kidney disease (CKD). This class of drugs stimulates endogenous erythropoietin production and, at the same time, improves iron absorption and mobilization of iron stores (less evident with daprodustat, vadadustat and enarodustat). Several studies have been published in the last few years showing that these agents are not inferior to standard therapy in correcting anemia associated with CKD. The efficacy of HIF-PHIs is coupled with a safety profile comparable to that of standard erythropoiesis stimulating agent (ESA) treatment. However, studies with HIF-PHIs were not long enough to definitively exclude the impact of new drugs on adverse events, such as cancer, death and possibly cardiovascular events, that usually occur after a long follow-up period. Kidney Disease: Improving Global Outcomes (KDIGO) recently reported the conclusions of the Controversies Conference on HIF-PHIs held in 2021. The goal of the present position paper endorsed by the Italian Society of Nephrology is to better adapt the conclusions of the latest KDIGO Conference on HIF-PHIs to the Italian context by reviewing the efficacy and safety of HIF-PHIs as well as their use in subpopulations of interest as emerged from more recent publications not discussed during the KDIGO Conference.

Risk Factors for Thromboembolic Events in Patients With Dialysis-Dependent CKD: Pooled Analysis of Four Global Roxadustat Phase 3 Trials

INTRODUCTION

Risk factors for thromboembolic events in patients with dialysis-dependent chronic kidney disease (CKD) receiving roxadustat are unknown. Iron deficiency has been reported as a risk factor for thrombosis in the general population.

METHODS

Thromboembolic events with onset before and after week 12 in patients receiving roxadustat were evaluated in this pooled analysis of four global phase 3 trials, PYRENEES, SIERRAS, HIMALAYAS, and ROCKIES. Baseline risk factors for thromboembolic events were investigated by Cox regression analyses. Nested case-control analyses with matched pairs of case-control data explored the relationship between thromboembolic events and last known laboratory parameters before event onset.

RESULTS

Of 2354 patients, 1026 thromboembolic events were observed in 568 patients. Baseline risk factors found included hemodialysis (vs peritoneal dialysis), advanced age (≥ 65 years), Black race, high high-sensitivity C-reactive protein, and history of thromboembolism, cardiovascular disease, or diabetes. Univariate case-control analyses revealed that high hemoglobin rate of rise (≥ 0.5 g/dL/week; odds ratio [OR] 2.09; 95% confidence interval [CI] 0.98-4.46) showed a trend towards increased risk of thromboembolic events before week 12, and high rate of hemoglobin decline was associated with events after week 12 (< - 0.5 g/dL/week; OR 3.73; 95% CI 1.68-8.27) as compared to stable hemoglobin levels (≥ - 0.1 to < 0.1 g/dL/week). Multivariate case-control analyses showed that low last known hemoglobin level (< 10 g/dL: adjusted OR 1.91; 95% CI 1.04-3.50; vs ≥ 12 g/dL) and low last known transferrin saturation (TSAT < 10%: adjusted OR 3.78; 95% CI 1.71-8.39; vs ≥ 30%) before event onset were associated with events after week 12. In patients with last known TSAT < 30%, higher roxadustat dose was associated with thromboembolic events; however, no association was observed in those with TSAT ≥ 30%.

CONCLUSIONS

Among various risk factors for thromboembolic events, it is reasonable to avoid a rapid increase and decline in hemoglobin levels as well as ensure TSAT ≥ 30%, rather than increasing the roxadustat dose. Graphical Abstract available for this article.

TRIAL REGISTRATION

NCT02278341, NCT02273726, NCT02052310, NCT02174731.

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

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

Targeting hypoxia-inducible factors: therapeutic opportunities and challenges

Hypoxia-inducible factors (HIFs) are highly conserved transcription factors that are crucial for adaptation of metazoans to limited oxygen availability. Recently, HIF activation and inhibition have emerged as therapeutic targets in various human diseases. Pharmacologically desirable effects of HIF activation include erythropoiesis stimulation, cellular metabolism optimization during hypoxia and adaptive responses during ischaemia and inflammation. By contrast, HIF inhibition has been explored as a therapy for various cancers, retinal neovascularization and pulmonary hypertension. This Review discusses the biochemical mechanisms that control HIF stabilization and the molecular strategies that can be exploited pharmacologically to activate or inhibit HIFs. In addition, we examine medical conditions that benefit from targeting HIFs, the potential side effects of HIF activation or inhibition and future challenges in this field.

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Safety and Efficacy of Hypoxia-Inducible Factor-Prolyl Hydroxylase Inhibitors vs. Erythropoietin-Stimulating Agents in Treating Anemia in Renal Patients (With or Without Dialysis): A Meta-Analysis and Systematic Review

Hypoxia-inducible factor-prolyl hydroxylase domain inhibitors (HIF-PHIs) are a novel group of drugs used to treat renal anemia, but their benefits vary among different trials. Our meta-analysis aims to assess the safety and efficacy of HIF-PHI versus erythropoiesis-stimulating agents (ESA) in managing anemia among patients with chronic kidney disease (CKD), regardless of their dialysis status. PubMed, Embase, and Google Scholar were queried to discover eligible randomized controlled trials (RCTs). To quantify the specific effects of HIF-PHI, we estimated pooled mean differences (MDs) and relative risks (RR) with 95% CIs. Our meta-analysis involved 22,151 CKD patients, with 11,234 receiving HIF-PHI and 10,917 receiving ESA from 19 different RCTs. The HIF-PHI used included roxadustat, daprodustat, and vadadustat. HIF-PHI yielded a slight but significant increase in change in mean hemoglobin (Hb) levels (MD: 0.06, 95% CI (0.00, 0.11); p = 0.03), with the maximum significant increase shown in roxadustat followed by daprodustat as compared to ESA. There was a significant decrease in efficacy outcomes such as change in mean iron (MD: -1.54, 95% CI (-3.01, -0.06); p = 0.04), change in mean hepcidin (MD: -21.04, 95% CI (-28.92, -13.17); p < 0.00001), change in mean ferritin (MD: -16.45, 95% CI (-27.17,-5.73); p = 0.03) with roxadustat showing maximum efficacy followed by daprodustat. As for safety, HIF-PHI showed significantly increased incidence in safety outcomes such as diarrhea (MD: 1.3, 95% CI (1.11, 1.51); p = 0.001), adverse events leading to withdrawal (MD: 2.03, 95% CI (1.5, 2.74), p = 0.00001) among 25 various analyzed outcomes. This meta-analysis indicates that HIF-PHIs present a potentially safer and more effective alternative to ESAs, with increased Hb levels and decreased iron usage in CKD patients without significantly increasing adverse events. Therefore, in these patients, we propose HIF-PHI alongside renal anemia treatment.

Novel anemia therapies in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Anemia is common in patients with chronic kidney disease and is associated with a high burden of morbidity and adverse clinical outcomes. In 2012, Kidney Disease: Improving Global Outcomes (KDIGO) published a guideline for the diagnosis and management of anemia in chronic kidney disease. Since then, new data from studies assessing established and emerging therapies for the treatment of anemia and iron deficiency have become available. Beginning in 2019, KDIGO planned 2 Controversies Conferences to review the new evidence and its potential impact on the management of anemia in clinical practice. Here, we report on the second of these conferences held virtually in December 2021, which focused on a new class of agents-the hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs). This report provides a review of the consensus points and controversies from this second conference and highlights areas that warrant prioritization for future research.

Hypoxia-inducible factor upregulation by roxadustat attenuates drug reward by altering brain iron homoeostasis

Substance use disorder remains a major challenge, with an enduring need to identify and evaluate new, translational targets for effective treatment. Here, we report the upregulation of Hypoxia-inducible factor-1α (HIF-1α) expression by roxadustat (Rox), a drug developed for renal anemia that inhibits HIF prolyl hydroxylase to prevent degradation of HIF-1α, administered either systemically or locally into selected brain regions, suppressed morphine (Mor)-induced conditioned place preference (CPP). A similar effect was observed with methamphetamine (METH). Moreover, Rox also inhibited the expression of both established and reinstated Mor-CPP and promoted the extinction of Mor-CPP. Additionally, the elevation of HIF-1α enhanced hepcidin/ferroportin 1 (FPN1)-mediated iron efflux and resulted in cellular iron deficiency, which led to the functional accumulation of the dopamine transporter (DAT) in plasma membranes due to iron deficiency-impaired ubiquitin degradation. Notably, iron-deficient mice generated via a low iron diet mimicked the effect of Rox on the prevention of Mor- or METH-CPP formation, without affecting other types of memory. These data reveal a novel mechanism for HIF-1α and iron involvement in substance use disorder, which may represent a potential novel therapeutic strategy for the treatment of drug abuse. The findings also repurpose Rox by suggesting a potential new indication for the treatment of substance use disorder.

Effects of pharmacological delay with roxadustat on multi-territory perforator flap survival in rats

Roxadustat (FG-4592) is a specific hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor. We investigated the effects of FG-4592 pretreatment on survival and second choke vessels of multi-territory perforator flaps in rats. In total, 72 rats were divided into two groups (n = 36 each): the experimental (FG-4592) group and the control group. FG-4592 was administered orally as a single dose of 60 mg/kg every other day; the first drug solution was administered to the animals 7 days before the surgical procedure. On postoperative day 7, the surviving flap area was calculated. At 12 h post-surgery, in the second choke zone in the flaps, macrovascular hinges were compared by angiography and imaging, and microvascular changes were assessed by histology. Laser Doppler imaging was used to evaluate flap perfusion at the second choke zone at 12 h and 7 days after surgery. At 7 days after surgery, the flap survival area and perfusion were significantly greater in rats given FG-4592 compared with controls. At 12 h after surgery, the diameter of macrovascular and microvascular vessels, nitric oxide content, perfusion, and the protein levels of HIF-1α and inducible nitric oxide synthase were also significantly greater in FG-4592-treated rats than controls. In conclusion, pretreatment with roxadustat may improve initial flap survival and dilate the second choke zone vessels in a multi-territory perforator flap.

Comparative effectiveness and acceptability of HIF prolyl-hydroxylase inhibitors versus for anemia patients with chronic kidney disease undergoing dialysis: a systematic review and network meta-analysis

Background: The comparative benefits and acceptability of HIF-PHIs for treating anemia have not been well researched to date. We sought to compare the effectiveness of 6 HIF-PHIs and 3 ESAs for the treatment of renal anemia patients undergoing dialysis. Data sources: Cochrane Central Register of Controlled Trials, PubMed, Embase, Cochrane Library, MEDLINE, Web of Science, and clinicaltrials.gov databases. Results: Twenty-five RCTs (involving 17,204 participants) were included, all of which were designed to achieve target Hb levels by adjusting thee dose of HIF-PHIs. Regarding the efficacy in achieving target Hb levels, no significant differences were found between HIF-PHIs and ESAs in Hb response at the dose-adjusted designed RCTs selected for comparison. Intervention with roxadustat showed a significantly lower risk of RBC transfusion than rhEPO, with an OR and 95% CI of 0.76 (0.56-0.93). Roxadustat and vadadustat had higher risks of increasing the discontinuation rate than ESAs; the former had ORs and 95% CIs of 1.58 (95% CI: 1.21-2.06) for rhEPO, 1.66 (1.16-2.38) for DPO (darbepoetin alfa), and 1.76 (1.70-4.49) for MPG-EPO, and the latter had ORs and 95% CIs of 1.71 (1.09-2.67) for rhEPO, 1.79 (1.29-2.49) for DPO, and 2.97 (1.62-5.46) for MPG-EPO. No differences were observed in the AEs and SAEs among patients who received the studied drugs. Results of a meta-analysis of gastrointestinal disorders among AEs revealed that vadadustat was less effect on causing diarrea than DPO, with an OR of 0.97 (95% CI, 0.9-0.99). Included HIF-PHIs, were proven to be more effective than ESAs in reducing hepcidin levels and increasing TIBC and serum iron level with OR of -0.17 (95% CI, -0.21 to -0.12), OR of 0.79 (95% CI, 0.63-0.95), and OR of 0.39 (95% CI, 0.33-0.45), respectively. Conclusion: HIF-PHIs and ESAs have their characteristics and advantages in treating anemia undergoing dialysis. With the selected dose-adjusted mode, some HIF-PHIs appeared to be a potential treatment for DD-CKD patients when ompared with rhEPO, due to its effectiveness in decreasing the risk of RBC transfusion rate or regulating iron or lipid metabolism while achieving target Hb levels. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=306511; Identifier: CRD42022306511.

An Overview of Safety and Efficacy Between Hypoxia-Inducible Factor-Prolyl-Hydroxylase Inhibitors and Erythropoietin-Stimulating Agents in Treating Anemia in Chronic Kidney Disease Patients

Anemia is one of the common complications in chronic kidney disease (CKD) patients. Erythropoietin and iron deficiencies are the major causes to develop anemia in CKD patients. Untreated anemia is associated with increased morbidity and mortality. Erythropoietin-stimulating agents (ESA) with iron supplementation are the standard for treating renal anemia. Although ESA with iron supplementation is an effective therapy in maintaining serum hemoglobin (Hb) levels, it increases the risk of several life-threatening adverse events such as hypertension, thromboembolism, cardiovascular morbidity, and mortality with long-term use. Therefore, effective alternate therapy with better safety and efficacy is needed to treat renal anemia. The newer oral therapy hypoxia-inducible factor-prolyl-hydroxylase inhibitors (HIF-PHI) can potentially be an effective alternative therapy in treating renal anemia. This review article compares the safety and efficacy between HIF-PHI and ESA in treating anemia in CKD patients. We conducted a comprehensive literature review of articles, including clinical trials, meta-analyses, and reviews, that compared the safety and efficacy between HIF-PHI and ESA. Studies have shown that the newer oral therapy, HIF-PHI, was non-inferior to ESA to maintain serum Hb levels in CKD patients. Moreover, the adverse event profile was almost similar in both groups. However, as the studies we reviewed have small sample sizes and short duration periods, the long-term effectiveness and safety of HIF-PHI over ESA in treating renal anemia cannot be established.

Therapeutics of managing reduced red cell mass associated with chronic kidney disease - Is there a case for earlier intervention?

Reduced red cell mass is a poor prognostic indicator in chronic kidney disease (CKD) patients. Whilst overt anaemia impacts on the quality of life of patients with CKD, lowered red cell mass may also compromise oxygen delivery to proximal tubular cells and contribute to progressive kidney injury. Epidemiological data from cats with CKD support this hypothesis although controlled interventional studies involving drugs that raise red cell mass in trials designed to test this hypothesis are lacking in both human and veterinary medicine. Recombinant analogues of erythropoietin (EPO) are currently standard of care for human CKD patients where low red cell mass impacts on their quality of life. Resistance to EPO is encountered in 20% to 40% of patients treated, probably due to functional iron deficiency, reflecting the difficulties of managing iron deficiency associated with the chronic inflammation of CKD. Similar issues are likely faced in managing anaemia in feline CKD although published data on the use of human EPO analogues are limited as such treatment in cats risks antibody formation resulting in red cell aplasia and transfusion dependency and so is reserved for late stage cases only. This article reviews the recent alternative therapeutic approach to increase red cell mass using HIF-prolyl hydroxylase inhibitors and explains their mode of action and theoretical advantages over EPO analogues in the context of iron metabolism. The results of human clinical trials and the potential benefit of adopting this approach in feline CKD patients are discussed.

Cardiac and Kidney Adverse Effects of HIF Prolyl-Hydroxylase Inhibitors for Anemia in Patients With CKD Not Receiving Dialysis: A Systematic Review and Meta-analysis

RATIONALE & OBJECTIVE

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) are novel, orally administered agents for anemia management in chronic kidney disease (CKD). We evaluated the cardiac and kidney-related adverse effects of HIF-PHIs among patients with CKD and anemia.

STUDY DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING & STUDY POPULATIONS

Patients with anemia and CKD not receiving maintenance dialysis.

SELECTION CRITERIA FOR STUDIES

RCTs comparing HIF-PHIs to placebo or an erythropoiesis-stimulating agent (ESA) with primary outcomes of cardiac and kidney-related adverse events (AEs).

DATA EXTRACTION

Two independent reviewers evaluated RCTs for eligibility and extracted relevant data.

ANALYTICAL APPROACH

Dichotomous variables were pooled using the Mantel-Haenszel method and presented as risk ratios (RRs). Subgroup analyses evaluated different intervention times and HIF-PHIs, as well as phase 2 versus phase 3 trials. The certainty of findings was rated according to GRADE criteria.

RESULTS

Twenty-three studies with 15,144 participants were included. No significant difference in the risk of cardiac AEs was observed between the HIF-PHIs group and the placebo (RR, 1.02 [95% CI, 0.89-1.16]; moderate certainty) or ESA (RR, 1.06 [95% CI, 0.98-1.14]; low certainty) groups. No significant difference in the risk of kidney-related AEs was observed between the HIF-PHIs group and the placebo (RR, 1.09 [95% CI, 0.98-1.20]; moderate certainty) or ESA (RR, 1.00 [95% CI, 0.94-1.06]; low certainty) groups. The occurrence of hypertension and hyperkalemia was higher in the HIF-PHIs group than in the placebo group (RRs of 1.35 [95% CI, 1.14-1.60] and 1.25 [95% CI, 1.03-1.51], respectively; both findings had high certainty). The occurrence of hypertension was lower in the HIF-PHIs group than in the ESA group (RR, 0.89 [95% CI, 0.81-0.98]; moderate certainty).

LIMITATIONS

The reporting criteria of cardiac and kidney-related AEs and dosage of HIF-PHIs were inconsistent across trials.

CONCLUSIONS

The occurrence of cardiac or kidney-related AEs in the HIF-PHI groups were not different compared with placebo or ESA groups.

REGISTRATION

Registered at PROSPERO with registration number CRD42021228243.

Effects of hypoxia-inducible factor prolyl hydroxylase inhibitors versus erythropoiesis-stimulating agents on iron metabolism and inflammation in patients undergoing dialysis: A systematic review and meta-analysis

Aims

This study aimed to evaluate the effects of hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) on iron metabolism and inflammation in dialysis-dependent chronic kidney disease (DD-CKD) patients.

Methods

PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov websites were searched for randomized controlled trials (RCTs) investigating HIF-PHIs versus ESAs for DD-CKD patients.

Key findings

Twenty studies with 14,737 participants were included in the meta-analysis, which demonstrated no significant difference in the effect of transferrin saturation and ferritin between HIF-PHIs and the ESAs group (MD, 0.65; 95%CI, -0.45 to 1.75; very low certainty; SMD, -0.03; 95% CI, -0.13 to 0.07; low certainty). However, HIF-PHIs significantly increased the iron (MD, 2.30; 95% CI, 1.40 to 3.20; low certainty), total iron-binding capacity (SMD, 0.82; 95% CI, 0.66 to 0.98; low certainty), and transferrin (SMD, 0.90; 95%CI, 0.74 to 1.05; moderate certainty) levels when compared with the ESAs group. In contrast, the hepcidin level and dosage of intravenous iron were significantly decreased in the HIF-PHIs group compared with the ESAs group (MD, -15.06, 95%CI, -21.96 to -8.16; low certainty; MD, -18.07; 95% CI, -30.05 to -6.09; low certainty). The maintenance dose requirements of roxadustat were independent of baseline CRP or hsCRP levels with respect to the effect on inflammation.

Significance

HIF-PHIs promote iron utilization and reduce the use of intravenous iron therapy. Furthermore, HIF-PHIs, such as roxadustat, maintain the erythropoietic response independent of the inflammatory state. Thus, HIF-PHIs may be an alternative treatment strategy for anemia in DD-CKD patients, where ESA is hyporesponsive due to iron deficiency and inflammation.

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

BACKGROUND

Five types of HIF-PHIs have been authorized for anemia treatment in CKD patients in China and Japan. These are enarodustat, roxadustat, daprodustat, vadadustat, and molidustat. How effectively they compare to ESAs about clinical results in CKD-DD patients is uncertain. This study examined the RCT evidence about the benefits and risks of HIF-PHIs and ESAs in dialysis CKD patients.

METHODS

We conducted an extensive investigation and network meta-analysis of RCTs. In these RCTs, patients with CKD-DD received one of five different HIF-PHI or ESAs, a placebo, and no medical intervention. Outcomes included hemoglobin, iron parameters, and adverse events, and there were four weeks of follow-up at least. A frequentist framework for multivariate random effects meta-analyzed the results. The effect sizes of categorical variables were displayed as odds ratios. Mean differences were employed for computing continuous outcomes with common units; otherwise, standardized mean differences were applied. The Cochrane tool evaluated the bias risk in RCTs.

RESULTS

26 RCTs with 14945 patients were qualified for inclusion. Compared to the placebo, HIF-PHIs and ESAs dramatically boosted hemoglobin without affecting serum iron. Roxadustat performed better hemoglobin levels than ESAs (MD 0.32, 95% CI 0.10 to 0.53) and daprodustat (0.46, 0.09 to 0.84). Roxadustat (91.8%) was the top hemoglobin treatment among all medical interventions, as determined by the SUCRA ranking. However, roxadustat caused more thrombosis and hypertension than ESAs (1.61, 1.22 to 2.12) and vadadustat (1.36, 1.01 to 1.82). The lowest rates of hypertension and thrombosis were seen in molidustat (80.7%) and ESAs (88.5%). Compared with a placebo, ESAs and HIF-PHIs all affected TSAT levels. Except for molidustat, the other four HIF-PHIs impact different iron parameters. Regarding ferritin reduction, roxadustat (90.9%) and daprodustat (60.9%) came out on top. Enarodustat (80.9%) and roxadustat (74%) placed best and second in lowering hepcidin levels. The former two medicines for TIBC improvement were vadadustat (98.7%) and enarodustat (80.9%).

CONCLUSION

The most effective treatment for hemoglobin correction is roxadustat. The superior efficacy of reducing hepcidin makes roxadustat and enarodustat appropriate for patients with inflammation. However, the increased risk of hypertension and thrombosis associated with roxadustat should be noted. In patients at risk for hypertension and thrombosis, molidustat and ESAs may be preferable options. When administering roxadustat and daprodustat, clinicians should check ferritin to assess iron storage. Lower TSAT in patients receiving HIF-PHIs and ESAs treatment suggests intravenous iron supplements are needed.

The role of roxadustat in chronic kidney disease patients complicated with anemia

The incidence of chronic kidney disease (CKD) is increasing worldwide and the current prevalence rate is 13.4%. There are > 120 million CKD patients in China and this number is expected to increase. One of the main abnormalities in patients with CKD and kidney impairment is decreased synthesis of erythropoietin (EPO), which causes anemia and affects iron metabolism. The probability of developing is higher in anemia patients with CKD than in the general population, and the incidence increases as kidney function decreases. Deficient EPO production by the kidney is the most important cause of renal anemia. Notably, anemia in patients with CKD has multiple causes, such as bleeding caused by platelet dysfunction, iron deficiency due to digestive and absorption disorders of the gastrointestinal tract, and shorter red blood cell life. Anemia is also a leading cause of hospitalization in patients with CKD. A new oral medication to treat renal anemia, the hypoxia-inducible factor prolyl hydroxylase inhibitor called roxadustat (FG-4592), regulates iron metabolism and promotes erythropoiesis. This drug has a therapeutic effect on patients with CKD. Roxadustat showed advantages over EPO in clinical experiments. This review summarizes the mechanisms of action, clinical applications, effectiveness, and safety of roxadustat.

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors and Iron Metabolism

The production of erythropoietin (EPO), the main regulator of erythroid differentiation, is regulated by hypoxia-inducible factor (HIF). HIF2α seems to be the principal regulator of EPO transcription, but HIF1α and 3α also may have additional influences on erythroid maturation. HIF is also involved in the regulation of iron, an essential component in erythropoiesis. Iron is essential for the organism but is also highly toxic, so its absorption and retention are strictly controlled. HIF also induces the synthesis of proteins involved in iron regulation, thereby ensuring the availability of iron necessary for hematopoiesis. Iron is a major component of hemoglobin and is also involved in erythrocyte differentiation and proliferation and in the regulation of HIF. Renal anemia is a condition in which there is a lack of stimulation of EPO synthesis due to decreased HIF expression. HIF prolyl hydroxylase inhibitors (HIF-PHIs) stabilize HIF and thereby allow it to be potent under normoxic conditions. Therefore, unlike erythropoiesis-stimulating agents, HIF-PHI may enhance iron absorption from the intestinal tract and iron supply from reticuloendothelial macrophages and hepatocytes into the plasma, thus facilitating the availability of iron for hematopoiesis. The only HIF-PHI currently on the market worldwide is roxadustat, but in Japan, five products are available. Clinical studies to date in Japan have also shown that HIF-PHIs not only promote hematopoiesis, but also decrease hepcidin, the main regulator of iron metabolism, and increase the total iron-binding capacity (TIBC), which indicates the iron transport capacity. However, concerns about the systemic effects of HIF-PHIs have not been completely dispelled, warranting further careful monitoring.

Open-label, Phase 2 study of roxadustat for the treatment of anemia in patients receiving chemotherapy for non-myeloid malignancies

Anemia is a common side effect of myelosuppressive chemotherapy; however, chemotherapy-induced anemia (CIA) management options are suboptimal. We evaluated the efficacy and safety of roxadustat in this setting. This open-label Phase 2 study included patients with non-myeloid malignancies and CIA (hemoglobin [Hb] ≤10 g/dL) who had planned concurrent myelosuppressive chemotherapy for ≥8 additional weeks. Oral roxadustat was administered for ≤16 weeks (starting dose 2.0 or 2.5 mg/kg, then titrated every 4 weeks). The primary efficacy endpoint was mean maximum change in Hb within 16 weeks of baseline without red blood cell (RBC) transfusion. Patients were assigned to roxadustat 2.0 (n = 31) or 2.5 mg/kg (n = 61) starting doses, and 89 were assessed for efficacy. The mean (standard deviation) maximum Hb change from baseline without RBC transfusion was 2.4 (1.5) and 2.5 (1.5) g/dL in the roxadustat 2.0 and 2.5 mg/kg groups, respectively. Median (range) time to Hb increase of ≥2 g/dL was 71 (57-92) days. Twelve patients (14.5%) had RBC transfusions (Week 5 to the end of treatment). Roxadustat was efficacious regardless of tumor type and chemotherapy regimen. Deep vein thrombosis (DVT) and pulmonary embolism (PE) occurred in 14 (15.2%) and nine (9.8%) patients, respectively, and three had serious adverse events attributed to roxadustat in the opinion of the investigators (PE: n = 2 [2.2%]; DVT: n = 1 [1.1%]). Roxadustat increased Hb in patients with CIA regardless of tumor type and chemotherapy regimen. Adverse events were consistent with observations in patients with advanced-stage malignancies.

Efficacy and Safety of Roxadustat in Patients with Chronic Kidney Disease: An Updated Meta-Analysis of Randomized Controlled Trials including 6,518 Patients

Background

Roxadustat is a newly listed oral hypoxia-inducible factor-proline enhancing enzyme inhibitor (HIF-PHI) in recent years. There have been some studies that have proved the efficacy of roxadustat on the treatment of renal anemia in patients with chronic kidney disease (CKD), but there are still different conclusions on its safety.

Methods

PubMed, Embase, Cochrane, and ClinicalTrials were searched for randomized controlled trials (RCTs) that assess efficacy and safety of roxadustat treatment for anemia in CKD patients. The Cochrane Literature Quality Evaluation Scale was used to evaluate the quality of included literature. We choose fixed-effects model or random effects model for data processing based on heterogeneity. It was considered statistically significant when p value <0.05.

Results

A total of 842 articles were retrieved, and 16 trials in the 15 articles were finally included. Roxadustat treatment significantly increased Hb levels. Iron (SMD 1.43, 95% CI 0.31 to 2.55), total iron-binding capacity (SMD 2.06, 95% CI 0.91 to 3.22), ferritin (WMD 21.33, 95% CI 3.04 to 39.62), transferrin saturation (SMD 4.17, 95% CI 3.90 to 4.45), and LDL-cholesterol (SMD -0.64, 95% CI -0.73 to -0.55) showed statistical significance in dialysis-dependent (DD) study. And hepcidin (SMD -1.56, 95% CI -2.63 to -0.50), transferrin (SMD 1.80, 95% CI 1.53 to 2.06), total iron-binding capacity (SMD 1.62, 95% CI 1.39 to 1.86), total cholesterol (SMD -0.88, 95% CI -1.68 to -0.09), ferritin (WMD -52.68, 95% CI -62.68 to -42.67), transferrin saturation (SMD -5.57, 95% CI -7.47 to -3.68), and LDL-cholesterol (SMD -0.85, 95% CI -1.37 to -0.34) showed statistical significance in not dialysis-dependent (NDD) study. In terms of safety, roxadustat treatment did not increase risk of total adverse events either in dialysis-dependent or not dialysis-dependent patients.

Conclusion

Roxadustat can effectively improve anemia in patients with chronic kidney disease. There was no significant difference in total adverse events compared with the control group.

Evolving Strategies in the Treatment of Anaemia in Chronic Kidney Disease: The HIF-Prolyl Hydroxylase Inhibitors

Chronic kidney disease (CKD) affects approximately 10% of the worldwide population; anaemia is a frequent complication. Inadequate erythropoietin production and absolute or functional iron deficiency are the major causes. Accordingly, the current treatment is based on iron and erythropoiesis stimulating agents (ESAs). Available therapy has dramatically improved the management of anaemia and the quality of life. However, safety concerns were raised over ESA use, especially when aiming to reach near-to-normal haemoglobin levels with high doses. Moreover, many patients show hypo-responsiveness to ESA. Hypoxia-inducible factor (HIF) prolyl hydroxylase domain (PHD) inhibitors (HIF-PHIs) were developed for the oral treatment of anaemia in CKD to overcome these concerns. They simulate the body's exposure to moderate hypoxia, stimulating the production of endogenous erythropoietin. Some molecules are already approved for clinical use in some countries. Data from clinical trials showed non-inferiority in anaemia correction compared to ESA or superiority for placebo. Hypoxia-inducible factor-prolyl hydroxylase domain inhibitors may also have additional advantages in inflamed patients, improving iron utilisation and mobilisation and decreasing LDL-cholesterol. Overall, non-inferiority was also shown in major cardiovascular events, except for one molecule in the non-dialysis population. This was an unexpected finding, considering the lower erythropoietin levels reached using these drugs due to their peculiar mechanism of action. More data and longer follow-ups are necessary to better clarifying safety issues and further investigate the variety of pathways activated by HIF, which could have either positive or negative effects and could differentiate HIF-PHIs from ESAs.

Disturbance of Hypoxia Response and Its Implications in Kidney Diseases

Significance: The disturbance of the hypoxia response system is closely related to human diseases, because it is essential for the maintenance of homeostasis. Given the significant role of the hypoxia response system in human health, therapeutic applications targeting prolyl hydroxylase-hypoxia-inducible factor (HIF) signaling have been attempted. Thus, systemically reviewing the hypoxia response-based therapeutic strategies is of great significance. Recent Advances: Disturbance of the hypoxia response is a characteristic feature of various diseases. Targeting the hypoxia response system is, thus, a promising therapeutic strategy. Interestingly, several compounds and drugs are currently under clinical trials, and some have already been approved for use in the treatment of certain human diseases. Critical Issues: We summarize the molecular mechanisms of the hypoxia response system and address the potential therapeutic implications in kidney diseases. Given that the effects of hypoxia response in kidney diseases are likely to depend on the pathological context, specific cell types, and the differences in the activation pattern of HIF isoforms, the precise application is critical for the treatment of kidney diseases. Although HIF-PHIs (HIF-PHD inhibitors) have been proven to be effective and well tolerated in chronic kidney disease patients with anemia, the potential on-target consequence of HIF activation and some outstanding questions warrant further consideration. Future Direction: The mechanism of the hypoxia response system disturbance remains unclear. Elucidation of the molecular mechanism of hypoxia response and its precise effects on kidney diseases warrants clarification. Considering the complexity of the hypoxia response system and multiple biological processes controlled by HIF signaling, the development of more specific inhibitors is highly warranted. Antioxid. Redox Signal. 37, 936-955.

Hypoxia-Inducible Factor-Prolyl Hydroxyl Domain Inhibitors: From Theoretical Superiority to Clinical Noninferiority Compared with Current ESAs?

Anemia is a common complication of chronic kidney disease; it is mainly treated with erythropoiesis-stimulating agents (ESAs) and iron. Experimental studies extensively investigated the mechanisms involved in the body's response to hypoxia and led to the discovery of the hypoxia-inducible factor (HIF) pathway and the enzymes regulating its function. HIF-prolyl-hydroxyl domain (PHD) inhibitors are a new class of oral drugs developed to treat anemia in chronic kidney disease. By inhibiting the function of PHD enzymes, they mimic the exposure to moderate hypoxia and stimulate the production of endogenous erythropoietin and very likely increase iron availability. Some data also suggest that their efficacy and, consequently, dose needs are less influenced by inflammation than ESAs. Overall, data from phases 2 and 3 clinical development showed efficacy in anemia correction and maintenance for all of the class molecules compared with placebo (superiority) or erythropoiesis-stimulating agents (noninferiority). Three molecules, roxadustat, vadadustat, and daprodustat, underwent extensive clinical investigation to assess their safety on hard cardiovascular end points, mortality, and special interest events (including cancer and thrombosis). Aside from vadadustat in the nondialysis population, at the prespecified primary analyses, all three molecules met the noninferiority margin for the risk of major cardiovascular events compared with erythropoiesis-stimulating agents or placebo. The reason for this discrepancy is difficult to explain. Other safety signals came from secondary analyses of some of the other randomized clinical trials, including a higher incidence of thrombosis. A more extensive clinical experience with post-marketing data on hard safety issues is needed to define better when and how to use HIF-PHD inhibitors compared with already available ESAs.

Bibliometric analysis of hypoxia inducible factor prolyl hydroxylase inhibitor in anemia

Objective: This study aimed to explore the global research status, hot topics, and future prospects in the field of the hypoxia inducible factor prolyl hydroxylase inhibitor (HIF-PHI) by bibliometric analysis.

Methods: The literatures about HIF-PHI were downloaded from the Web of Science Core Collection and Pubmed database from inceptions to January.10th. 2022. The VOSviewer 1.6.18 was used to explore the bibliometric networks and research priorities of HIF-PHI.

Results: A total of 409 papers about HIF-PHI were included, involving 1,674 authors from 548 institutions in 43 countries. The number of HIF-PHI literatures showed an upward trend, with steady growth from 2016 to 2020 and rapid growth in 2021. Tadao Akizawa, Masaomi Nangaku and Alexander R Cobitz published the most literatures. The United States, Japan and China contributed the most publications. The three most contributed institutions are Astellas Pharma Inc., the Showa University and Glaxosmithkline. Therapeutic Apheresis and Dialysis, American Journal of Nephrology and Clinical Pharmacology in Drug Development are the most productive journals. The main hot topics of HIF-PHI field are anemia, chronic kidney disease, hif-phi, epoetin and roxadustat.

Conclusion: The United States and Japan are dominant in the field of HIF-PHI research. The discovery and clinical application of HIF-PHI is a great boon for patients with renal anemia. However, due to the short clinical application time of HIF-PHI, and its long-term efficacy and safety still need time to prove. In addition, more cooperation should be carried out between European and American countries and Asian countries to better prove the clinical value of HIF-PHI.

Risk of infection in roxadustat treatment for anemia in patients with chronic kidney disease: A systematic review with meta-analysis and trial sequential analysis

Background: Many studies demonstrated that roxadustat (FG-4592) could increase hemoglobin (Hb) levels effectively in anemia patients with chronic kidney disease (CKD). However, its safety remains controversial. This study aims to explore the risk of infection for CKD patients treated with roxadustat, especially focused on sepsis.

Methods: We thoroughly searched for the randomized controlled trials (RCTs) comparing treatment with roxadustat versus erythropoiesis stimulating agents (ESAs) or placebo in PubMed, Embase, Cochrane Library, ClinicalTrials.gov, European Union Clinical Trials Register. Both on and not on dialysis anemia patients with CKD were included. Primary outcomes contained the incidence rates of sepsis. Secondary outcomes included infection-related consequences (septic shock and other infection events), general safety outcomes [all-cause mortality, treatment-emergent adverse events (TEAEs) and treatment-emergent serious adverse events (TESAEs)] and iron parameters. Moreover, a trial sequential analysis (TSA) was conducted to assess if the results were supposed to be a robust conclusion.

Results: Eighteen RCTs (n = 11,305) were included. Overall, the incidence of sepsis (RR: 2.42, 95% CI [1.50, 3.89], p = 0.0003) and cellulitis (RR: 2.07, 95% CI [1.24, 3.44], p = 0.005) were increased in the roxadustat group compared with placebo group. In non-dialysis-dependent (NDD) CKD patients, the incidence of cellulitis (RR 2.01, 95% CI [1.23, 3.28], p = 0.005) was significantly higher in roxadustat group than that in the ESAs or placebo group. Both groups showed similar results in the incidence of septic shock (RR 1.29, 95% CI [0.86, 1.94], p = 0.22). A significant increased risk of all-cause mortality [risk ratios (RR): 1.15, 95% confidence interval (CI) [1.05, 1.26], p = 0.002] was found in roxadustat treatment, and TSA confirmed the result. Compared with ESAs or placebo, both the incident rates of TEAEs (RR:1.03, 95% CI [1.01, 1.04], p = 0.008) and TESAEs (RR: 1.06, 95% CI [1.02, 1.11], p = 0.002) were significantly increased in roxadustat group. As for iron parameters, changes from baseline (Δ) of hepcidin (MD: -26.46, 95% CI [-39.83, -13.09], p = 0.0001), Δ ferritin and Δ TSAT were remarkably lower in the roxadustat group, while Δ Hb, Δ iron and Δ TIBC increased significantly versus those in ESAs or placebo group.

Conclusion: We found evidence that incidence rates of sepsis and cellulitis are higher in roxadustat group compared with placebo. This may be the result of improved iron homeostasis. The risk of all-cause mortality, TEAEs and TESAEs in CKD patients also increased in patients treated with roxadustat. We need more clinical and mechanistic studies to confirm whether roxadustat really causes infection.

Hypoxia-inducible factor stabilisers for the anaemia of chronic kidney disease

BACKGROUND

Anaemia occurs in chronic kidney disease (CKD) and is more prevalent with lower levels of kidney function. Anaemia in CKD is associated with death related to cardiovascular (CV) disease and infection. Established treatments include erythropoiesis-stimulating agents (ESAs), iron supplementation and blood transfusions. Oral hypoxia-inducible factors (HIF) stabilisers are now available to manage anaemia in people with CKD.

OBJECTIVES

We aimed to assess the benefits and potential harms of HIF stabilisers for the management of anaemia in people with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 22 November 2021 through contact with the Information Specialist using search terms relevant to our review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised and quasi-randomised studies evaluating hypoxia-inducible factors stabilisers compared to placebo, standard care, ESAs or iron supplementation in people with CKD were included.

DATA COLLECTION AND ANALYSIS

Five authors independently extracted data and assessed the risk of bias. Treatment estimates were summarised using random effects pair-wise meta-analysis and expressed as a relative risk (RR) or mean difference (MD), with a corresponding 95% confidence interval (CI). Evidence certainty was assessed using GRADE.

MAIN RESULTS

We included 51 studies randomising 30,994 adults. These studies compared HIF stabilisers to either placebo or an ESA. Compared to placebo, HIF stabiliser therapy had uncertain effects on CV death (10 studies, 1114 participants): RR 3.68, 95% CI 0.19 to 70.21; very low certainty evidence), and nonfatal myocardial infarction (MI) (3 studies, 822 participants): RR 1.29, 95% CI 0.31 to 5.36; I² = 0%; very low certainty evidence), probably decreases the proportion of patients requiring blood transfusion (8 studies, 4329 participants): RR 0.51, 95% CI 0.44 to 0.60; I² = 0%; moderate certainty evidence), and increases the proportion of patients reaching the target haemoglobin (Hb) (10 studies, 5102 participants): RR 8.36, 95% CI 6.42 to 10.89; I² = 37%; moderate certainty evidence). Compared to ESAs, HIF stabiliser therapy may make little or no difference to CV death (17 studies, 10,340 participants): RR 1.05, 95% CI 0.88 to 1.26; I² = 0%; low certainty evidence), nonfatal MI (7 studies, 7765 participants): RR 0.91, 95% CI 0.76 to 1.10; I² = 0%; low certainty evidence), and nonfatal stroke (5 studies, 7285 participants): RR 1.06, 95% CI 0.71 to 1.56; I² = 8%; low certainty evidence), and had uncertain effects on fatigue (2 studies, 3471 participants): RR 0.80, 95% CI 0.56 to 1.16; I² = 0%; very low certainty evidence). HIF stabiliser therapy probably decreased the proportion of patients requiring blood transfusion (11 studies, 10,786 participants): RR 0.87, 95% CI 0.76 to 1.00; I² = 25%; moderate certainty evidence), but may make little or no difference on the proportion of patients reaching the target Hb (14 studies, 4601 participants): RR 1.00, 95% CI 0.93 to 1.07; I² = 70%; low certainty evidence), compared to ESA. The effect of HIF stabilisers on hospitalisation for heart failure, peripheral arterial events, loss of unassisted dialysis vascular access patency, access intervention, cancer, infection, pulmonary hypertension and diabetic nephropathy was uncertain. None of the included studies reported life participation. Adverse events were rarely and inconsistently reported.

AUTHORS' CONCLUSIONS

HIF stabiliser management of anaemia had uncertain effects on CV death, fatigue, death (any cause), CV outcomes, and kidney failure compared to placebo or ESAs. Compared to placebo or ESAs, HIF stabiliser management of anaemia probably decreased the proportion of patients requiring blood transfusions, and probably increased the proportion of patients reaching the target Hb when compared to placebo.

Hypoxia-inducible factor prolyl hydroxylase inhibitors for anaemia in maintenance dialysis: a meta-analysis

BACKGROUND

Anaemia is a common complication of end-stage renal disease (ESRD) that relies on dialysis. Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) is a new class of small-molecule oral drugs for the treatment of anaemia in chronic kidney disease. They demonstrate several advantages over traditional exogenous erythropoietin (EPO). We conducted a meta-analysis of studies that compared the efficacy of HIF-PHI in erythropoiesis and iron metabolism, and its safety with EPO in maintenance dialysis patients.

METHODS

A sensitive search strategy in the PubMed, EMBASE and Cochrane databases identified all citations for randomised controlled trials (RCTs) comparing HIF-PHI agents with EPO/placebo through December 2021.

RESULTS

Fourteen RCTs were identified, which included 2738 patients. No statistical difference was found in haemoglobin increase (p = 0.37) between HIF-PHI treatment and EPO using the random-effects model. HIF-PHI administration upregulated transferrin (MD 36.12, 95% CI 27.04-45.20) and soluble transferrin receptors (sTfR) (MD 1.28, 95% CI 0.44-2.13), but did not statistically reduce hepcidin level (p = 0.37). Total and LDL-cholestrol levels were suppressed by HIF-PHI (MD - 0.99, 95% CI - 1.34 to  - 0.63) (MD - 0.99, 95% CI - 1.34 to - 0.64), while triglyceride (TG) was not different between HIF-PHI and EPO (p = 0.74). The total incident rates of treatment-emergent adverse events (TEAE) (p = 0.20) from HIF-PHI treatment were not different from those of erythropoietin, while the treatment-emergent serious adverse events (TSAE) (p = 0.02) were higher in the HIF-PHI group than those in the EPO controls with the fixed-effect model.

CONCLUSION

HIF-PHI could effectively upregulate and maintain haemoglobin levels in patients with anaemia receiving maintenance dialysis. Furthermore, HIF-PHI could elevate iron metabolism activity and utility without inducing treatment-associated serious adverse events. Robust data from larger RCTs with longer treatment duration and follow-up are needed.

Roxadustat regulates iron metabolism in dialysis-dependent and non-dialysis-dependent chronic kidney disease patients: A meta-analysis

BACKGROUND/PURPOSE

The effect of roxadustat on iron homeostasis in patients with chronic kidney disease (CKD) is unclear. This study aimed to evaluate the efficacy of roxadustat for the treatment of iron metabolism disorders in dialysis-dependent (DD) and non-dialysis-dependent (NDD) CKD patients.

METHODS

We searched the PubMed, Embase, China National Knowledge Internet and Web of Science databases for randomized controlled trials (RCTs). The primary outcomes were changes in serum iron, total iron binding capacity (TIBC), transferrin saturation (TSAT), ferritin, transferrin, and hepcidin. The secondary outcomes included the changes in hemoglobin (Hb) and the incidences of adverse events (AEs) and severe adverse events (SAEs).

RESULTS

Twelve RCTs comprising 4976 participants were included. Compared to the control group, increases in the serum iron (SMD = 0.21, 95% CI: 0.15 to 0.27, P < 0.00001), TIBC (SMD = 1.02, 95% CI: 0.82 to 1.22, P < 0.00001) and transferrin levels (WMD = 0.55, 95% CI: 0.41 to 0.69, P < 0.00001) were found in the roxadustat group. Compared to the control group, decreases in the ferritin levels (WMD = -37.82, 95% CI: -59.89 to -15.74, P = 0.0008) and hepcidin levels (WMD = -24.04, 95% CI: -36.28 to -11.79, P = 0.0001) were observed in the roxadustat group. The meta-analysis showed that roxadustat significantly increases Hb levels (WMD = 0.77, 95% CI: 0.42 to 1.12, P < 0.0001). The incidences of AEs and SAEs in the roxadustat group was significantly higher than that in the control group (RR = 1.03, 95% CI: 1.00 to 1.07, P = 0.04; RR = 1.08, 95% CI: 1.00 to 1.15, P = 0.04).

CONCLUSION

Our findings suggest that roxadustat could effectively improve iron metabolism in patients with CKD.

The Efficacy and Safety of Roxadustat for Anemia in Patients With Chronic Kidney Disease: A Meta-Analysis

Background: Chronic kidney disease (CKD) is a global public health problem, and anemia is a common complication in CKD patients. Roxadustat (FG-4592) is an oral hypoxia-inducible factor (HIF) stabilizer. Roxadustat has been shown in studies to keep up with and increase hemoglobin better than placebo or erythropoietin. The purpose of this meta-analysis was to assess the efficacy and safety of roxadustat.

Methods: We searched CBM, CNKI, VIP, Wanfang Database, PubMed, Cochrane Library, Embase, and Web of Science for randomized controlled trials of roxadustat for the treatment of anemia in CKD patients. The papers were screened using rigorous criteria and their quality was assessed using the Cochrane 5.1.0 assessment manual for randomized controlled trials (RCTs). RevMan 5.3 was used to extract and synthesize data for meta-analysis.

Results: There were 8 RCTs (7 articles) in all, and 1,364 patients with chronic kidney disease anemia were involved. The overall quality of the studies included was satisfactory. The meta-analysis findings revealed that roxadustat can considerably enhance hemoglobin, transferrin, and total iron binding capacity (TIBC) in both dialysis-dependent (DD) and non-dialysis-dependent (NDD) patients: Hemoglobin (Hb): DD: [SMD = 0.23, 95% CI (0.01, 0.44), p = 0.04], NDD: [SMD = 2.08, 95% CI (1.23, 2.93) p < 0.000001]; transferrin: DD: [SMD = 0.78, 95% CI (0.24, 1.32), p = 0.004], NDD: [SMD = 1.37, 95% CI (0.76, 1.98), p < 0.0001]; TIBC: DD [SMD = 0.97, 95% CI (0.64, 1.29), p < 0.00001], NDD [SMD = 1.34, 95% CI (0.9, 1.78), p < 0.00001]. After roxadustat therapy, patients’ serum iron levels were considerably higher in the dialysis group than in the control group, but there was no significant change in the NDD group [SMD = 0.42, 95% CI (0.27, 0.57), p < 0.00001]. In the NDD group, hepcidin, ferritin, and transferrin saturation (TSAT) were significantly reduced after roxadustat treatment: Hepcidin [SMD = −1.59, 95% CI (−2.69, −0.49), p = 0.005], ferritin [SMD = −0.51, 95% CI (−0.72, 0.3) p < 0.00001], TSAT [SMD = −0.41, 95% CI (−0.62, 0.2), p < 0.0001]. In terms of safety, adverse events (AE) [SMD = 1.08, 95% CI (0.98, 1.18) p = 0.11] and serious adverse events (SAE) [SMD = 1.32, 95% CI (0.97, 1.9) p = 0.08] were not significantly different between the two groups.

Conclusion: Roxadustat can improve anemia in NDD patients with chronic kidney disease, and its short-term safety was comparable to that of the comparison group.

Safety and Effectiveness of Roxadustat in Dialysis-Dependent Patients With Renal Anemia: A Hospital-Based Cohort Study

Background

Randomized controlled trials (RCTs) have shown the efficacy and safety of Roxadustat and conclude that it has the potential to change the treatment for anemia associated with chronic kidney disease. However, the experience of its use from clinical perspectives post-approval is lacking.

Aim

Using a clinical practice context, this study aims to compare Roxadustat's effectiveness and tolerability with Erythropoietin (EPO) in patients with renal anemia undergoing dialysis.

Methods

We examined the clinical records of patients with a diagnosis of renal anemia on dialysis who were prescribed Roxadustat or Erythropoietin at the department of nephrology of the First Affiliated Hospital of Gannan Medical University from January 2021 to December 2021. Eligible hemodialysis (HD) or peritoneal dialysis (PD) patients with renal anemia, aged >18 or <75 years, without infection, active bleeding, and malignancy were recruited. These patients received Roxadustat or EPO based on the preferential prescription choice made by the nephrologists of the department. We retrospectively attempted to determine the treatment response measured by the change in hemoglobin rate, from baseline up to six months. We also explored the impact of various factors on the treatment response and reported adverse events.

Results

A total of 106 patients have been included in the final analysis, with 53 patients in each group. The mean age of the study group was 49.9 ± 13.6 years with the main Hb level at the baseline of 8.1 g/dL ± 1.23 g/dl. The gain of hemoglobin from the baseline averaged over six months was 2.2 ± 2.11 g/dl in the Roxadustat group compared with 1.1 ± 1.67 g/dL in the EPO group (p=0.01). As compared to EPO,Roxadustat reduced the total cholesterol level by -0.59 ± 1.08 mmol/l versus -0.01 ± 1.28 mmol/l (p=0012) and the low-density lipoprotein (LDL) cholesterol by -0.48 ± 1.07 mmol/l versus -0.47 ± 1.05 (p=0.017) in the first three months. Associated factors with a non-response to treatment were age greater than 65 years (OR=6, 95% CI: 1.23-32.46, p=0.02), hypertension (OR=3.5, 95%CI: 0.89-13.25, p=0.060), and heart failure (OR=4.18, 95%CI:4.18 1.04-20.39, p=0.040). Although the proportion of hospitalization and infection was higher in the EPO group and the incidences of gastrointestinal symptoms (vomiting, nausea) and blood transfusions were higher in the Roxadustat group, there were no statistically significant differences.

Conclusion

Roxadustat improved hemoglobin compared to erythropoietin in patients undergoing dialysis with a safe profile but precautions should be taken for old patients with a cardiovascular medical history.

Renal hypoxia-HIF-PHD-EPO signaling in transition metal nephrotoxicity: friend or foe?

The kidney is the main organ that senses changes in systemic oxygen tension, but it is also the key detoxification, transit and excretion site of transition metals (TMs). Pivotal to oxygen sensing are prolyl-hydroxylases (PHDs), which hydroxylate specific residues in hypoxia-inducible factors (HIFs), key transcription factors that orchestrate responses to hypoxia, such as induction of erythropoietin (EPO). The essential TM ion Fe is a key component and regulator of the hypoxia–PHD–HIF–EPO (HPHE) signaling axis, which governs erythropoiesis, angiogenesis, anaerobic metabolism, adaptation, survival and proliferation, and hence cell and body homeostasis. However, inadequate concentrations of essential TMs or entry of non-essential TMs in organisms cause toxicity and disrupt health. Non-essential TMs are toxic because they enter cells and displace essential TMs by ionic and molecular mimicry, e. g. in metalloproteins. Here, we review the molecular mechanisms of HPHE interactions with TMs (Fe, Co, Ni, Cd, Cr, and Pt) as well as their implications in renal physiology, pathophysiology and toxicology. Some TMs, such as Fe and Co, may activate renal HPHE signaling, which may be beneficial under some circumstances, for example, by mitigating renal injuries from other causes, but may also promote pathologies, such as renal cancer development and metastasis. Yet some other TMs appear to disrupt renal HPHE signaling, contributing to the complex picture of TM (nephro-)toxicity. Strikingly, despite a wealth of literature on the topic, current knowledge lacks a deeper molecular understanding of TM interaction with HPHE signaling, in particular in the kidney. This precludes rationale preventive and therapeutic approaches to TM nephrotoxicity, although recently activators of HPHE signaling have become available for therapy.

WT1: The Hinge Between Anemia Correction and Cancer Development in Chronic Kidney Disease

Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHIs) emerge as promising agents to treat anemia in chronic kidney disease (CKD) but the major concern is their correlated risk of cancer development and progression. The Wilms’ tumor gene, WT1, is transcriptionally regulated by HIF and is known to play a crucial role in tumorigenesis and invasiveness of certain types of cancers. From the mechanism of action of HIF–PHIs, to cancer hypoxia and the biological significance of WT1, this review will discuss the link between HIF, WT1, anemia correction, and cancer. We aimed to reveal the research gaps and offer a focused strategy to monitor the development and progression of specific types of cancer when using HIF–PHIs to treat anemia in CKD patients. In addition, to facilitate the long-term use of HIF–PHIs in anemic CKD patients, we will discuss the strategy of WT1 inhibition to reduce the development and progression of cancer.

Roxadustat Versus Epoetin Alfa for Treating Anemia in Patients with Chronic Kidney Disease on Dialysis: Results from the Randomized Phase 3 ROCKIES Study

Background

Concerns regarding cardiovascular safety with current treatments for anemia in patients with dialysis-dependent (DD)-CKD have encouraged the development of alternatives. Roxadustat, an oral hypoxia-inducible factor prolyl hydroxylase inhibitor, stimulates erythropoiesis by increasing endogenous erythropoietin and iron availability.

Methods

In this open-label phase 3 study, patients with DD-CKD and anemia were randomized 1:1 to oral roxadustat three times weekly or parenteral epoetin alfa per local clinic practice. Initial roxadustat dose depended on erythropoiesis-stimulating agent dose at screening for patients already on them and was weight-based for those not on them. The primary efficacy end point was mean hemoglobin change from baseline averaged over weeks 28‒52 for roxadustat versus epoetin alfa, regardless of rescue therapy use, tested for noninferiority (margin, −0.75 g/dl). Adverse events (AEs) were assessed.

Results

Among 2133 patients randomized (n=1068 roxadustat, n=1065 epoetin alfa), mean age was 54.0 years, and 89.1% and 10.8% were on hemodialysis and peritoneal dialysis, respectively. Mean (95% confidence interval) hemoglobin change from baseline was 0.77 (0.69 to 0.85) g/dl with roxadustat and 0.68 (0.60 to 0.76) g/dl with epoetin alfa, demonstrating noninferiority (least squares mean difference [95% CI], 0.09 [0.01 to 0.18]; P<0.001). The proportion of patients experiencing ≥1 AE and ≥1 serious AE was 85.0% and 57.6% with roxadustat and 84.5% and 57.5% with epoetin alfa, respectively.

Conclusions

Roxadustat effectively increased hemoglobin in patients with DD-CKD, with an AE profile comparable to epoetin alfa.

Clinical Trial registry name and registration number:

Safety and Efficacy Study of Roxadustat to Treat Anemia in Patients With Chronic Kidney Disease, on Dialysis. ClinicalTrials.gov Identifier: NCT02174731.

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.

Efficacy and Safety of Daprodustat Vs rhEPO for Anemia in Patients With Chronic Kidney Disease: A Meta-Analysis and Trial Sequential Analysis

Introduction: Daprodustat, a novel hypoxia-inducible factor prolyl-hydroxylase inhibitor (HIF-PHI), its efficacy and safety remain unclear. Thus, we conducted this meta-analysis aiming at investigating its efficacy and safety on the treatment of patients with chronic kidney disease (CKD)-related anemia.

Methods: We systematically searched for relevant studies in PubMed, Embase, Cochrane Library and Clinical Trial Registries databases from inception until December 2021. We selected randomized controlled trials comparing daprodustat with recombinant human erythropoietin (rhEPO) in anemia patients with CKD with or without dialysis.

Results: Seven studies including 7933 patients met the inclusion criteria. For both nondialysis-dependent (NDD-) CKD and dialysis-dependent (DD-) CKD patients, the pooled results showed that there was no significant difference in the changes in hemoglobin levels between the daprodustat and rhEPO groups (mean difference (MD) = −0.01, 95% confidence interval (CI) = −0.38, 0.35, p = 0.95; MD = 0.15, 95% CI = −0.29, 0.60, p = 0.50; respectively). In addition, a significant increase in transferrin saturation (TSAT), total iron binding capacity (TIBC) and total iron was observed in daprodustat groups compared with rhEPO groups in DD-CKD patients (p < 0.05). As for safety, the overall frequency of adverse events was similar between the daprodustat and rhEPO groups in DD-CKD patients (relative risk (RR) = 0.99, 95%CI = 0.92, 1.06, p = 0.76), and the trial sequential analysis (TSA) confirmed this result. But for NDD-CKD patients, the incidence of adverse events in the daprodustat groups was significantly higher than that of rhEPO groups (RR = 1.04, 95%CI = 1.01,1.07, p = 0.02), while the TSA corrected this result. No trend of increasing incidence of serious adverse events was found in all daprodustat treated patients, but the TSA could not confirm this result.

Conclusion: Although daprodustat was noninferior to rhEPO in correcting anemia in both NDD-CKD and DD-CKD patients, it seemed to have a better effect on optimizing iron metabolism in DD-CKD patients. Daprodustat may be a promising alternative for the treatment of anemia in patients with CKD. However, due to the lack of included studies, future researches are needed to further evaluate the therapeutic effect of daprodustat.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier CRD42021229636.

Randomized Study on the Efficacy of Standard Versus Low Roxadustat Dose for Anemia in Patients on Peritoneal Dialysis

Introduction

We aimed to investigate whether a lower starting dose of roxadustat (∼1–1.4 mg/kg) converted from erythropoiesis-stimulating agent (ESA) could achieve a comparable hemoglobin (Hb) target (≥100 and ≤120 g/l) compared with the standard weight-based dose (∼1.5–2 mg/kg) at week 12 through a peritoneal dialysis (PD) cohort.

Methods

A 12-week multicenter randomized, parallel-controlled, open-label, pilot clinical trial enrolled adult patients who had undergone PD treatment for >3 months with renal anemia. Participants were randomized in blocks of 4 in a 1:1 ratio to either the standard-dose group (n = 50) or the low-dose group (n = 50). The primary end point was the proportion of patients achieving the Hb target at week 12.

Results

Baseline demographic and clinical characteristics of the 2 groups were comparable. There was no difference in the proportion of patients who met the Hb target at week 12, that is, 26 patients (52%) versus 31 patients (62%) in the low-dose group and standard-dose group, respectively (P = 0.31). The Hb levels significantly increased in both groups from baseline to week 12; the median change of Hb levels was 5.0 (0.0–14.3) g/l (P < 0.001) for the standard-dose group and 6.0 (−3.3 to 16.3) g/l for the low-dose group (P = 0.005) (P = 0.581 for between groups).

Conclusion

This study suggests that a lower starting dose of roxadustat effectively achieves the Hb target as standard-dose does among patients on PD. (ClinicalTrials.gov number, NCT04454879).

Roxadustat for the treatment of anemia in patients with lower-risk myelodysplastic syndrome: Open-label, dose-selection, lead-in stage of a phase 3 study

Anemia is the predominant cytopenia in myelodysplastic syndromes (MDS) and treatment options are limited. Roxadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor approved for the treatment of anemia of chronic kidney disease in the UK, EU, China, Japan, South Korea, and Chile. MATTERHORN is a phase 3, randomized, double-blind, placebo-controlled study to assess the efficacy and safety of roxadustat in anemia of lower risk-MDS. Eligible patients had baseline serum erythropoietin ≤ 400 mIU/mL, and a low packed RBC transfusion burden. In this open-label (OL), dose-selection, lead-in phase, enrolled patients were assigned to 1 of 3 roxadustat starting doses (n = 8 each): 1.5, 2.0, and 2.5 mg/kg. The primary efficacy endpoint of the OL phase was the proportion of patients with transfusion independence (TI) for ≥ 8 consecutive weeks in the first 28 treatment weeks. A secondary efficacy endpoint was the proportion of patients with a ≥ 50% reduction in RBC transfusions over an 8-week period compared with baseline. Adverse events were monitored. Patients were followed for 52 weeks. Of the 24 treated patients, TI was achieved in 9 patients (37.5%) at 28 and 52 weeks; 7 of these patients were receiving 2.5 mg/kg dose when TI was achieved. A ≥ 50% reduction in RBC transfusions was achieved in 54.2% and 58.3% of patients at 28 and 52 weeks, respectively. Oral roxadustat dosed thrice weekly was well tolerated. There were no fatalities or progression to acute myeloid leukemia. Based on these outcomes, 2.5 mg/kg was the chosen starting roxadustat dose for the ongoing double-blind study phase.

Efficacy and Safety of Vadadustat for Anemia in Patients With Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Background: Vadadustat is a novel drug for treating anemia patients with chronic kidney disease (CKD), but its effect and safety remain uncertain. This study aimed to summarize the evidence for vadadustat in the treatment of CKD patients with anemia.

Methods: PubMed, Ovid Medline, Embase, Cochrane CENTRAL, Wanfang Data, China National Knowledge Infrastructure and an international trial register were searched from their inception to June 2021 for randomized controlled trials (RCTs) comparing the efficacy and safety of vadadustat to those of placebo or erythropoiesis-stimulating agents (ESAs) in treating anemia in CKD patients. Data were pooled in a meta-analysis, with results expressed as the mean difference for continuous outcomes and relative risk for categorical outcomes with 95% confidence intervals (95% CIs). The certainty of evidence was rated according to Cochrane methods and the GRADE approach.

Results: Ten RCTs comparing vadadustat with placebo (4 RCTs) or darbepoetin alfa (6 RCTs) were included (n = 8,438 participants). Compared with placebo, vadadustat increased the hemoglobin (Hb) response rate (risk ratio 5.27; 95% CI: 2.69 to 10.31; p &lt; 0.001; high certainty of evidence) and Hb level from baseline (∆Hb) (mean difference (MD) 1.28; 95% CI: 0.83 to 1.73; p &lt; 0.001; low certainty of evidence). Compared with placebo or darbepoetin alfa, vadadustat decreased hepcidin (MD -36.62; 95% CI: −54.95 to −18.30; p &lt; 0.001) and ferritin (MD −56.24; 95% CI: −77.37 to −35.11; p &lt; 0.001) levels and increased iron-binding capacity (MD 24.38; 95% CI: 13.69 to 35.07; p &lt; 0.001), with a low to moderate certainty of evidence. Moderate to high certainty evidence suggested that compared with placebo or darbepoetin alfa, vadadustat significantly increased the risk of nausea and diarrhea but did not significantly increase the risk of serious adverse events, especially all-cause mortality, cardiac events and nonfatal stroke.

Conclusion: Vadadustat may safely improve Hb levels and promote iron utilization in CKD patients with anemia without increasing the incidence of serious adverse events.

Iron Deficiency in Heart Failure: Mechanisms and Pathophysiology

Iron is an essential micronutrient for a myriad of physiological processes in the body beyond erythropoiesis. Iron deficiency (ID) is a common comorbidity in patients with heart failure (HF), with a prevalence reaching up to 59% even in non-anaemic patients. ID impairs exercise capacity, reduces the quality of life, increases hospitalisation rate and mortality risk regardless of anaemia. Intravenously correcting ID has emerged as a promising treatment in HF as it has been shown to alleviate symptoms, improve quality of life and exercise capacity and reduce hospitalisations. However, the pathophysiology of ID in HF remains poorly characterised. Recognition of ID in HF triggered more research with the aim to explain how correcting ID improves HF status as well as the underlying causes of ID in the first place. In the past few years, significant progress has been made in understanding iron homeostasis by characterising the role of the iron-regulating hormone hepcidin, the effects of ID on skeletal and cardiac myocytes, kidneys and the immune system. In this review, we summarise the current knowledge and recent advances in the pathophysiology of ID in heart failure, the deleterious systemic and cellular consequences of ID.

Clinical Pharmacokinetics and Pharmacodynamics of Roxadustat

The pharmacokinetics of roxadustat are well characterized, with an apparent volume of distribution after oral administration of 22–57 L, apparent clearance of 1.2–2.65 L/h, and renal clearance of 0.030–0.026 L/h in healthy volunteers; the elimination half-life is 9.6–16 h. Plasma binding is 99% and the fraction eliminated by hemodialysis is 2.34%. As an interpretation of the pharmacodynamics of roxadustat, we proposed a concept with a hypothetical cascade of two subsequent effects, first on erythropoetin (EPO) and second on hemoglobin (delta Hb). The primary effect on EPO is observed within a few hours after roxadustat administration and can be modeled using the sigmoidal Hill equation. The concentration at half-maximum effect can be inferred at 10–36 µg/mL, the Hill coefficient at 3.3, and the effect bisection time at 10–17 h, corresponding to EPO half-life. The subsequent effect on hemoglobin (delta Hb) is observed after several weeks and can be interpreted as an irreversible, dose proportional, unsaturable effect, continuing in agreement with the lifespan of red blood cells of 63–112 days.