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

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

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

Intertwined regulators: hypoxia pathway proteins, microRNAs, and phosphodiesterases in the control of steroidogenesis

Oxygen sensing is of paramount importance for maintaining cellular and systemic homeostasis. In response to diminished oxygen levels, the hypoxia-inducible factors (HIFs) orchestrate various biological processes. These pivotal transcription factors have been identified as key regulators of several biological events. Notably, extensive research from our group and others has demonstrated that HIF1α exerts an inverse regulatory effect on steroidogenesis, leading to the suppression of crucial steroidogenic enzyme expression and a subsequent decrease in steroid levels. These steroid hormones occupy pivotal roles in governing a myriad of physiological processes. Substantial or prolonged fluctuations in steroid levels carry detrimental consequences across multiple organ systems and underlie various pathological conditions, including metabolic and immune disorders. MicroRNAs serve as potent mediators of multifaceted gene regulatory mechanisms, acting as influential epigenetic regulators that modulate a broad spectrum of gene expressions. Concomitantly, phosphodiesterases (PDEs) play a crucial role in governing signal transduction. PDEs meticulously manage intracellular levels of both cAMP and cGMP, along with their respective signaling pathways and downstream targets. Intriguingly, an intricate interplay seems to exist between hypoxia signaling, microRNAs, and PDEs in the regulation of steroidogenesis. This review highlights recent advances in our understanding of the role of microRNAs during hypoxia-driven processes, including steroidogenesis, as well as the possibilities that exist in the application of HIF prolyl hydroxylase (PHD) inhibitors for the modulation of steroidogenesis.

Treatment of chronic kidney disease in older populations

As the world population ages, an expected increase in the prevalence of chronic kidney disease (CKD) among older individuals will pose a considerable challenge for health care systems in terms of resource allocation for disease management. Treatment strategies for older patients with CKD should ideally align with those applied to the general population, focusing on minimizing cardiovascular events and reducing the risk of progression to kidney failure. Emerging therapies, such as SGLT-2 inhibitors and GLP-1 receptor agonists, hold promise for the effective management of CKD in older individuals. In addition, non-pharmacological interventions such as nutritional and exercise therapies have a crucial role. These interventions enhance the effects of pharmacotherapy and, importantly, contribute to the maintenance of cognitive function and overall quality of life. Various factors beyond age and cognitive function must be taken into account when considering kidney replacement therapy for patients with kidney failure. Importantly, all treatment options, including dialysis, transplantation and conservative management approaches, should be tailored to the individual through patient-centred decision-making. The dynamic integration of digital technologies into medical practice has the potential to transform the management of CKD in the aging population.

Iron biology

Iron is a fundamental element for biological life, from bacteria to humans. Iron is essential for cell function and survival, energy production and metabolism, whereas increased levels cause oxidative stress. It is also a constituent of haemoglobin and thus it is necessary for oxygen transportation through the body. Given these multiple functions, the regulation of iron metabolism is complex and tight coupled with oxygen homeostasis at tissue and cellular levels, thanks to the interaction with the hypoxia inducible factor system. In patients with chronic kidney disease (CKD), iron deficiency significantly contributes to anaemia development. This frequently overlaps with chronic inflammation, causing iron- restricted erythropoiesis. To add further complexity, metabolic hyperferritinemia may, on one hand, increase the risk for CKD and, on the other, overlaps with functional iron deficiency. Excessive intracellular iron in certain cell types during CKD can also mediate cellular death (called ferroptosis), and contribute to the pathogenesis of kidney damage, atherosclerosis and vascular calcifications. This review is aimed at broadening the perspective of iron metabolism in the setting of CKD not just as a contributor to anaemia in CKD patients, but also as an important player with an impact on cell metabolism, renal fibrosis and the cardiovascular system.

Bridging the Gap Between CKD Management Paradigms in Transplant and Nontransplant Settings: Published Evidence, Challenges, and Perspectives

Kidney transplantation (KT) is the best treatment for patients with kidney failure, associated with improved survival and quality of life compared with maintenance dialysis. However, despite constant improvements in the assessment and management of the alloimmune response, KT patients frequently demonstrate a reduced estimated glomerular filtration rate. Therefore, the usual complications of chronic kidney disease (CKD), such as anemia, hypertension, metabolic acidosis, hyperkalemia, or persistent secondary hyperparathyroidism, are highly prevalent after KT. However, their underlying mechanisms are different in the transplant setting (compared with the nontransplanted CKD population), and management recommendations are based on relatively poor-quality data. In recent years, new therapies have emerged, significantly improving kidney and cardiovascular outcomes of non-KT patients with CKD. Whether those new drugs could improve the outcomes of KT patients has largely been under investigated so far. In this review, we will address the challenges of the management of a KT patient with a reduced estimated glomerular filtration rate, cover the published evidence, and highlight the critical knowledge gaps.

TRANSFUSION-INDUCED HLA SENSITISATION IN WAITLIST PATIENTS AND KIDNEY TRANSPLANT RECIPIENTS

HLA sensitisation remains an impediment to successful solid organ transplantation, whether it be chances of receiving a transplant offer or subsequent transplant longevity. Current treatments targeting HLA antibodies lack long term effectiveness, therefore preventing HLA sensitisation should remain a priority in all potential waitlist candidates and transplant recipients. Recent advances in the management of anaemia in patients with chronic kidney disease may reduce the need for red cell transfusions. However, data from several anaemia intervention studies of novel therapeutic agents have shown that a need for transfusion will remain. It has also been increasingly recognised that blood transfusions following kidney transplantation, especially in the peri-operative period, are common. Routine data on transfusion incidence, indications and outcomes, is not captured by most kidney and transplant registries across the globe. This restricts the evidence to inform both clinicians and patients on the clinical effects of transfusion, which have been considered both an allogeneic stimulus and to be immunomodulatory. This review aims to provide an update on what is currently known about transfusion-induced HLA sensitisation in waitlist candidates and transplant recipients, summarises where evidence is lacking and demonstrates the distinct need for patient blood management guidelines in the field of kidney transplantation.

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitors as a New Treatment Option for Anemia in Chronic Kidney Disease

Anemia plays an important role in chronic kidney disease (CKD) progression because it worsens the quality of life and increases the risk of cardiovascular complications in CKD patients. In such cases, anemia is mainly caused by endogenous erythropoietin (EPO) and iron deficiencies. Therefore, KDIGO and ERBP guidelines for anemia treatment in CKD patients focus on recombinant EPO and iron supplementation. A recent new treatment option for anemia in CKD patients involves blocking the hypoxia-inducible factor (HIF) system with prolyl hydroxylase inhibitors (PHIs), what causes increasing endogenous EPO production and optimizing the use of iron. Clinical studies have shown that the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) covered in this manuscript-roxadustat, vadadustat, daprodustat, and molidustat-effectively increase hemoglobin (Hb) levels in both non-dialyzed and dialyzed CKD patients. Moreover, these medicines reduce blood lipid levels and do not accelerate CKD progression. However, blockage of the HIF system by HIF-PHIs may be associated with adverse effects such as cardiovascular complications, tumorogenesis, hyperkalemia. and retinopathy. More extensive and long-term clinical trials of HIF-PHIs-based anemia treatment in CKD patients are needed, and their results will indicate whether HIF-PHIs represent an effective and safe alternative to EPO and iron supplementation for anemia treatment in CKD patients.

Case report: Roxadustat overdose in an anemia patient of chronic kidney disease: insight beyond insignificant consequence

A 71-year-old man with a 20-year history of grade 3 hypertension experienced kidney dysfunction 2 years earlier. His serum creatinine (SCr) at the time was 140 μmol/L [with estimated glomerular filtration rate (eGFR) of 43.9 ml/min per 1.73m2], for which he received irbesartan since. At initial presentation, the spot urine dipstick protein was 1+, with an albumin-to-creatinine ratio of 230 mg/g (0-30) and normal urine sediments. The SCr was 176 μmol/L (eGFR = 32.8 ml/min per 1.73m2). The hemoglobulin (Hb) level decreased from 102 to 96 g/L despite oral ferrous succinate 100 mg twice daily starting 2 months ago. Roxadustat (ROXA) 50 mg (body weight, 70 kg) three times weekly was then prescribed. Unfortunately, the patient mistakenly took the drug at 50 mg three times a day (i.e., 1,050 mg instead of the intended 150 mg per week), which was 3.5 times the recommended starting dose for non-dialysis-dependent chronic kidney disease (CKD) patients (100 mg three times weekly for body weight >60 kg) and two times the highest drug manual-recommended weekly dose (2.5 mg/kg three times weekly) approved in the country. When the attending nephrologist discovered the misuse 1 month later, the patient reported no apparent discomfort, and his home blood pressure was in the range 110-130/60-80 mmHg. Repeat blood tests showed that the Hb increased from 96 to 163 g/L and the SCr from 199 to 201 μmol/L in a month. The serum alanine transaminase (ALT) remained within the normal range (from 12 U/L at baseline to 20 U/L), while the serum total and indirect bilirubin levels were slightly elevated. ROXA was withheld immediately. In 30 days, the serum bilirubin returned to baseline, but the Hb decreased from 163 to 140 g/L, and then to 108 g/L after 3 months. On the other hand, the SCr increased from 179 to 203 μmol/L. At 9 months after the initial dosing, when the SCr increased to 256 μmol/L and the Hb decreased to 94 g/L again, ROXA 50 mg three times weekly was reinitiated uneventfully. Herein, by introducing a case who erroneously consumed twice the highest recommended dose of ROXA for a month, but had apparently no obvious discomfort or unfavorable consequence, we attempt to provide a brief overview of the mechanism of action, characteristics, drug metabolism, and side effect profile associated with this agent.

Physician and Patient Preferences for Treatment of Anemia Associated with Chronic Kidney Disease in Japan: A Survey Including Best-Worst Scaling

Background

Several treatment options are available for anemia associated with chronic kidney disease (CKD); however, there remains a lack of awareness of physician and patient preferences regarding these treatments. We aimed to explore physicians' and patients' perceptions and preferences regarding the management of anemia of CKD in Japan.

Methods

A web-based survey, including best-worst scaling (BWS), was conducted with physicians who had treated ≥1 patient with anemia of CKD in the preceding year, and with patients with CKD who self-reported a clinical diagnosis of anemia of CKD or low hemoglobin levels. A three-step approach was used comprising cognitive interviews, a pilot survey, and a main survey. The BWS survey results were analyzed using multinomial logit and hierarchical Bayesian models.

Results

The survey was completed by 906 participants: 103 patients (average age 60.6 years; 77.7% male) and 803 physicians (166 nephrologists, 214 cardiologists, 137 diabetologists, and 286 general internists). Almost all (96.0%) physicians surveyed considered anemia of CKD to be an important condition to treat. Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors had the highest treatment satisfaction among physicians, whereas patients had the highest satisfaction with both erythropoietin-stimulating agent therapy and HIF-PH inhibitors. Approximately one-third (35.9%) of patients surveyed indicated that they were receiving treatment. When comparing the relative importance of attributes and levels, physicians favored efficacy (particularly improvement in hemoglobin levels), whereas patients favored safety (particularly a lower rate of severe adverse events).

Conclusion

Although a majority of physicians consider treatment of CKD-related anemia important, differences in the perceptions and usage of medications exist between medical specialties. Preferences for the management of anemia of CKD vary between physicians and patients; therefore, patient involvement in treatment decisions may help optimize outcomes.

Ferroptosis-based advanced therapies as treatment approaches for metabolic and cardiovascular diseases

Ferroptosis has attracted attention throughout the last decade because of its tremendous clinical importance. Here, we review the rapidly growing body of literature on how inhibition of ferroptosis may be harnessed for the treatment of common diseases, and we focus on metabolic and cardiovascular unmet medical needs. We introduce four classes of preclinically established ferroptosis inhibitors (ferrostatins) such as iron chelators, radical trapping agents that function in the cytoplasmic compartment, lipophilic radical trapping antioxidants and ninjurin-1 (NINJ1) specific monoclonal antibodies. In contrast to ferroptosis inducers that cause serious untoward effects such as acute kidney tubular necrosis, the side effect profile of ferrostatins appears to be limited. We also consider ferroptosis as a potential side effect itself when several advanced therapies harnessing small-interfering RNA (siRNA)-based treatment approaches are tested. Importantly, clinical trial design is impeded by the lack of an appropriate biomarker for ferroptosis detection in serum samples or tissue biopsies. However, we discuss favorable clinical scenarios suited for the design of anti-ferroptosis clinical trials to test such first-in-class compounds. We conclude that targeting ferroptosis exhibits outstanding treatment options for metabolic and cardiovascular diseases, but we have only begun to translate this knowledge into clinically relevant applications.

Prevention of Chronic Kidney Disease and Its Complications in Older Adults

In an era marked by a global demographic shift towards an aging society, there is a heightened prevalence of chronic kidney disease (CKD) among older adults. The burden of CKD spans from kidney-related complications to impacting psychological well-being, giving rise to depressive symptoms and caregiver burnout. This article delves into CKD prevention strategies within the context of aging, contributing to the discourse by exploring its multifaceted aspects. The prevention of CKD in the older adults necessitates a comprehensive approach. Primary prevention is centered on the modification of risk factors, acknowledging the intricate interplay of various comorbidities. Secondary prevention focuses on early CKD identification. Tertiary prevention aims to address factors contributing to CKD progression and complications, emphasizing the importance of timely interventions. This comprehensive strategy aims to enhance the quality of life for individuals affected by CKD, decelerating the deterioration of functional status. By addressing CKD at multiple levels, this approach seeks to effectively and compassionately care for the aging population.

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.

The temporal trends of prevalence and years lived with disability of anaemia in China, Japan, and South Korea, from 1990 to 2021: Results from the Global Burden of Disease Study 2021

Background

Studies have shown that the disease burden of anaemia varies globally, yet they have not yet determined its exact extent in East Asian countries specifically. We thus aimed to investigate the prevalence and years lived with disability (YLDs) due to anaemia from 1990 to 2021 in China, Japan, and South Korea.

Methods

We extracted the prevalence and YLDs with their age-standardised rates (ASRs) in China, Japan, and South Korea from the Global Burden of Disease Study 2021, stratified by sex, age, and causes. We then examined the temporal trend of anaemia burden from 1990 to 2021 using joinpoint analysis and the association of anaemia burden with the Human Development Index and Universal Health Index through Spearman's correlation analysis.

Results

In 2021, anaemia affected 136 million people in China (95% uncertainty interval (UI) = 131, 141), with ASRs of prevalence of 8.9% (95% UI = 8.6, 9.3), and accounted for 3.0 million YLDs (95% UI = 2.0, 4.4). It affected 13.6 million people in Japan (95% UI = 11.8, 16.0), with ASRs of prevalence of 7.4% (95% UI = 6.1, 9.0), and caused 181 thousand YLDs (95% UI = 108, 282). It also affected 2.7 million individuals in South Korea (95% UI = 2.4, 3.0), with ASRs of prevalence of 5.2% (95% UI = 4.6, 5.7), and led to 34 thousand YLDs (95% UI = 22, 55). We observed a significant gender discrepancy in the anaemia burden in these three countries, with the prevalence and YLD rates in women being almost twice as high as those in men. Moreover, the peak age of the anaemia burden shifted toward higher age groups in all three countries, particularly in Japan. Chronic kidney disease was responsible for a growing share of anaemia cases and YLDs, especially in adults aged more than 60 years in Japan and South Korea. Haemoglobinopathies were another noticeable cause of anaemia in China, though dietary iron deficiency remained the leading cause. Both socioeconomic development and essential health service coverage showed negative associations with the anaemia burden in the three countries in the past three decades, though with differential patterns.

Conclusions

Anaemia remains a major public health issue in China, Japan, and South Korea; targeted surveillance and interventions are recommended for high-risk populations and cause-specific anaemia.

Iron Deficiency in Newly Referred Patients With Chronic Renal Failure

Addressing iron deficiency is the key to managing anemia in patients with chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs) and hypoxia-inducible factor prolyl-hydroxylase inhibitors (HIF-PHIs) are being prescribed to an increasing number of patients with CKD by primary physicians following the emergence of newer agents for the management of renal anemia. Among the 361 (average age: 76.8±12.1 years; 54.0% males) patients with stages 4 and 5 CKD newly referred to the nephrology department of our hospital between 2018 and 2023 who had evaluable transferrin saturation (TSAT) and ferritin levels, 169 patients (47%) had iron deficiency (ferritin <100 ng/mL or ferritin 100-300 ng/mL with TSAT <20%). The estimated glomerular filtration rate (eGFR), hemoglobin level, TSAT, and median ferritin level were 17.0±7.0 mL/min/1.73 m², 10.8±2.1 g/dL, 27.5±13.1%, and 130 ng/mL, respectively. ESAs, HIF-PHIs, and iron supplements were prescribed to 35 (9.7%), 17 (4.7%), and 35 (9.4%) patients, respectively. No significant differences were observed between the iron indices of the ESA group; however, the serum ferritin levels in the HIF-PHIs group were significantly lower than in those in the no-medication group (P=0.02). Multivariable logistic regression analysis revealed that age, female sex, eGFR, medications for renal anemia, and a history of ischemic heart disease were associated with iron deficiency (P<0.05). Although patients with renal failure tend to exhibit anemia, attention should be paid to iron deficiency anemia in addition to renal anemia, especially in patients with renal failure and a history of ischemic heart disease.

Erythropoiesis and estimated fluid volume regulation following initiation of ipragliflozin treatment in patients with type 2 diabetes mellitus and chronic kidney disease: A post-hoc analysis of the PROCEED trial

AIMS

To analyse the changes in erythropoietic and estimated fluid volume parameters after the initiation of ipragliflozin, a sodium-glucose co-transporter 2 inhibitor, in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD).

METHODS

This was a post-hoc analysis of the PROCEED trial, which evaluated the effect of 24-week ipragliflozin treatment on endothelial dysfunction in patients with T2DM and CKD. We evaluated the changes in erythropoietic and estimated fluid volume parameters from baseline to 24 weeks post-treatment in 53 patients who received ipragliflozin (ipragliflozin group) and 55 patients with T2DM and CKD without sodium-glucose co-transporter 2 inhibitors (control group), a full analysis set of the PROCEED trial.

RESULTS

The increases in haemoglobin [estimated group difference, 0.5 g/dl; 95% confidence interval (CI), 0.3-0.8; p < .001], haematocrit (estimated group difference, 2.2%; 95% CI, 1.3-3.1; p < .001) and erythropoietin (estimated log-transformed group difference, 0.1; 95% CI, 0.01-0.3; p = .036) were significantly greater in the ipragliflozin group than those in the control group. Ipragliflozin treatment was significantly associated with an increase in erythropoietin, independent of the corresponding change in haemoglobin (β = 0.253, p < .001) or haematocrit (β = 0.278, p < .001). Reductions in estimated plasma volume (estimated group difference, -7.94%; 95% CI, -11.6 to -4.26%; p < .001) and estimated extracellular volume (estimated group difference, -181.6 ml; 95% CI, -275.7 to -87.48 ml; p < .001) were significantly greater in the ipragliflozin group than those in the control group.

CONCLUSIONS

Erythropoiesis was enhanced and estimated fluid volumes were reduced by ipragliflozin in patients with T2DM and CKD.

CLINICAL TRIAL

PROCEED trial (registration number: jRCTs071190054).

Anemia in Patients After Stem Cell Transplantation and in Kidney Transplant Recipients

Hematopoietic stem cell transplant (HSCT) is the treatment of choice in various hematologic diseases, and kidney transplantation (KTx) is the best therapy for end-stage kidney disease. Chronic kidney disease (CKD) occurs relatively often after both types of transplantations. Anemia after both HSCT and KTx may be due to CKD and other reasons. This study aimed to assess the prevalence of anemia to CKD in 156 prevalent patients after HSCT and 80 after KTx. According to the World Health Organization's definition (hemoglobin <13 g/dL for men and <12 g/dL for women), the prevalence of anemia in the studied cohort after HSCT was 13% in women and 35% in men and for those after KTx, it was29% in men and 11%. Anemia in KTx was found in 46% of patients, whereas CKD was present in 53%. After HSCT, anemia was associated with CKD in 56% of women and 17% of men. In KTx, anemia and CKD was diagnosed in 21% of patients. Patients with anemia after KTx had significantly lower glomerular filtration rate (GFR), hemoglobin, and significantly higher creatinine levels. Age was related to the estimated GFR (eGFR; r = -0.39, P < .001) in patients who underwent HSCT and had anemia. In patients without anemia, age was negatively related to eGFR (r = -0.56, P < .001) and the hemoglobin-to-platelet count (r = 0.62, P < .001). In KTx, hemoglobin was related to eGFR (r = 0.35, P < .001), and age was related to eGFR (r = -0.20, P < .05). The type of induction therapy immunosuppressive regimen (anti-thymocyte globulin vs basiliximab vs no induction) did not affect the prevalence of anemia in the KTx population studied. Anemia is relatively common in CKD after HSCT. In both CKD and coexistent anemia, nephrology referral is to be considered to optimize therapy, including nephroprotection.

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.

Improving Kidney Disease Care: One Giant Leap for Nephrology

Nephrology is an ever-evolving field of medicine. The importance of such a discipline is related to the high clinical impact of kidney disease. In fact, abnormalities of kidney function and/or structure are common in the general population, reaching an overall prevalence of about 10%. More importantly, the onset of kidney damage is related to a strikingly high risk of cardiovascular events, mortality, and progression to kidney failure which, in turn, compromises quality and duration of life. Attempts to comprehend the pathogenesis and molecular mechanisms involved in kidney disease occurrence have prompted the development and implementation of novel drugs in clinical practice with the aim of treating the 'specific cause' of kidney disease (including chronic kidney disease, glomerular disease, and genetic kidney disorders) and the main immunological complications following kidney transplantation. Herein, we provide an overview of the principal emerging drug classes with proved efficacy in the context of the aforementioned clinical conditions. This can represent a simplified guide for clinical nephrologists to remind them of the vast and heterogeneous armamentarium of drugs that should be used in the present and the future to improve the management of patients suffering from kidney disease.

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.

Use of SGLT2 Inhibitors vs GLP-1 RAs and Anemia in Patients With Diabetes and CKD

Importance

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are associated with lower anemia risk, based on findings from post hoc analyses of the CREDENCE and DAPA-CKD trials; however, the effectiveness of SGLT2 inhibitors in a more generalizable type 2 diabetes (T2D) and chronic kidney disease (CKD) population, with active comparisons pertinent to current practice, is unknown.

Objective

To evaluate and compare anemia incidence between SGLT2 inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1 RAs) among patients with T2D and CKD stages 1 to 3.

Design, Setting, and Participants

This retrospective cohort study used target trial emulation of an expanded CREDENCE and DAPA-CKD study framework. The study was conducted among adults with T2D and CKD initiating SGLT2 inhibitors or GLP-1 RAs between January 1, 2016, and December 31, 2021, with follow-up until December 31, 2022. The study was conducted at the Chang Gung Medical Foundation, the largest multi-institutional hospital system in Taiwan.

Exposures

Initiation of SGLT2 inhibitors or GLP-1 RAs.

Main Outcomes and Measures

The primary outcome was a composite of anemia outcomes, including anemia event occurrence (hemoglobin level <12-13 g/dL or International Statistical Classification of Diseases, Tenth Revision, Clinical Modification diagnosis codes) or anemia treatment initiation. Changes in hematological parameters, including hemoglobin level, hematocrit level, and red blood cell count, were evaluated during the follow-up period for as long as 3 years.

Results

The cohort included a total of 13 799 patients with T2D and CKD, initiating SGLT2 inhibitors (12 331 patients; mean [SD] age, 62.4 [12.3] years; 7548 [61.2%] male) or GLP-1 RAs (1468 patients; mean [SD] age, 61.5 [13.3] years; 900 [61.3%] male). After the median follow-up period of 2.5 years, patients receiving SGLT2 inhibitors had lower incidence of composite anemia outcomes (hazard ratio [HR], 0.81; 95% CI, 0.73-0.90) compared with those receiving GLP-1 RAs. SGLT2 inhibitors were associated with a lower incidence of anemia events (HR, 0.79; 95% CI, 0.71-0.87) but not with a lower rate of anemia treatment initiation (HR, 0.99; 95% CI, 0.83-1.19). Changes in hematological parameters for SGLT2 inhibitors and GLP-1 RAs throughout the 3-year follow-up period supported the primary analyses.

Conclusions and Relevance

In this multi-institutional cohort study with target trial emulation, SGLT2 inhibitors were associated with a decreased risk of composite anemia outcomes, especially anemia event occurrences. SGLT2 inhibitors may be considered as an adjunct therapy to reduce anemia incidence in patients with T2D and CKD.

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.

Effect of SGLT2 inhibitors on anemia and their possible clinical implications

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have demonstrated cardiovascular and renal benefits in patients with type 2 diabetes mellitus, heart failure, or chronic kidney disease. Since the first studies with these drugs, an initial increase in hemoglobin/hematocrit levels was observed, which was attributed to an increase in hemoconcentration associated with its diuretic effect, although it was early appearent that these drugs increased erythropoietin levels and erythropoiesis, and improved iron metabolism. Mediation studies found that the increase in hemoglobin was strongly associated with the cardiorenal benefits of these drugs. In this review, we discuss the mechanisms for improving erythropoiesis and the implication of the increase in hemoglobin on the cardiorenal prognostic benefit of these drugs.

Sodium-Glucose Transporter 2 (SGLT2) Inhibitors and Iron Deficiency in Heart Failure and Chronic Kidney Disease: A Literature Review

Heart failure (HF) and chronic kidney disease (CKD) are associated with high mortality. In both disorders, impaired iron homeostasis, mostly in the form of a functional iron deficiency, is a frequent co-morbidity. In HF, functional iron deficiency and management by i.v. iron supplementation have been proven to affect both prognosis and functional capacity. In the same context, iron supplementation is routine for the adequate management of renal anemia in CKD. In numerous recent studies in HF and in CKD, sodium-glucose transporter 2 (SGLT2) inhibitor treatment has been proven to significantly reduce mortality. Furthermore, the same trials showed that these drugs alleviate iron deficiency and anemia. These effects of SGLT2 inhibitors may be due to an amelioration of inflammation with reduced interleukin-6 (IL-6) and to an enhancement of autophagy with increased sirtuin 1 (SIRT1), both associated with modified production of hepcidin and enhanced ferritinophagy. However, the exact pathogenic basis of the beneficial SGLT2 inhibitor action is not fully elucidated. Nevertheless, effects on iron homeostasis might be a potential explanatory mechanism for the powerful SGLT2 inhibitors' cardiovascular and renal outcome benefits. In addition, the interaction between iron supplementation and SGLT2 inhibitors and its potential impact on prognosis remains to be clarified by future studies. This review represents a significant effort to explore the complex relationships involved, seeking to elucidate the intricate mechanisms by which SGLT2 inhibitors influence iron homeostasis.

Bone Disorders in Pediatric Chronic Kidney Disease: A Literature Review

Intense changes in mineral and bone metabolism are frequent in chronic kidney disease (CKD) and represent an important cause of morbidity and reduced quality of life. These disorders have conventionally been defined as renal osteodystrophy and classified based on bone biopsy, but due to a lack of bone biopsy data and validated radiological methods to evaluate bone morphology in children, it has been challenging to effectively assess renal osteodystrophy in pediatric CKD; the consequence has been the suboptimal management of bone disorders in children. CKD-mineral and bone disorder (CKD-MBD) is a new expression used to describe a systemic disorder of mineral and bone metabolism as a result of CKD. CKD-MBD is a triad of biochemical imbalances in calcium, phosphate, parathyroid hormone, and vitamin D; bone deformities and soft tissue calcification. This literature review aims to explore the pathogenesis, diagnostic approach, and treatment of CKD-MBD in children and the effects of renal osteodystrophy on growing skeleton, with a specific focus on the biological basis of this peculiar condition.

Cardiovascular safety of current and emerging drugs to treat anaemia in chronic kidney disease: a safety review

INTRODUCTION

Erythropoiesis-stimulating agents (ESAs) are the standard of treatment for anemia in chronic kidney disease. Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHI) are small molecules that stimulate endogenous erythropoietin synthesis.

AREAS COVERED

The cardiovascular safety of ESAs and HIF-PHIs. We performed a PubMed search using several key words, including anemia, chronic kidney disease, safety, erythropoiesis stimulating agents, HIF-PH inhibitors.

EXPERT OPINION

ESAs are well-tolerated drugs with a long history of use; there are safety concerns, especially when targeting high hemoglobin levels. HIF-PHIs have comparable efficacy to ESAs in correcting anemia. Contrary to expectations, randomized phase 3 clinical trials have shown that overall HIF-PHIs were non-inferior to ESA or placebo with respect to the risk of cardiovascular endpoints. In addition, some phase 3 trials raised potential safety concerns regarding cardiovascular and thrombotic events, particularly in non-dialysis patients.Today, HIF-PHIs represent an additional treatment option for anemia in patients with chronic kidney disease. This has made the management of anemia in CKD more complex and heterogeneous. A better understanding of the mechanisms causing hypo-responsiveness to ESAs, combined with an individualized approach that balances ESAs, HIF-PHIs and iron doses, could increase the benefits while reducing the risks.