Nonhematologic complications of erythropoietin therapy

Rubrometabolic Syndrome

Metabolic syndrome (MS), a conglomeration of several conditions including obesity, type 2 diabetes mellitus (T2DM), insulin resistance, elevated blood pressure, and dyslipidemia is reaching epidemic proportions. Anemia is caused by iron deficiency or dysregulation of iron homeostasis, leading to tissue hypoxia. Coexistence of anemia and MS or its components has been reported in the literature. The term "rubrometabolic syndrome" acts as a unifying entity linking the importance of blood in health and anemia in MS; it justifies two principles - redness of blood and low-grade inflammation. Chronic low-grade inflammation in MS affects iron metabolism leading to anemia. Tissue hypoxia that results from the anemic condition seems to be a major causative factor for the exacerbation of several microvascular and macrovascular components of T2DM, which include diabetic neuropathy, nephropathy, retinopathy, and cardiovascular complications. In obesity, anemia leads to malabsorption of micronutrients and can complicate the management of the condition by bariatric surgery. Anemia interferes with the diagnosis and management of T2DM, obesity, dyslipidemia, or hypertension due to its effect on pathological tests as well as medications. Since anemia in MS is multifaceted, the management of anemia is challenging as overcorrection of anemia with erythropoietin-stimulating agents can cause detrimental effects. These limitations necessitate availability of an effective and safe therapy that can maintain and elevate the hemoglobin levels along with maintaining the physiological balance of other systems. This review discusses the physiological links between anemia and MS along with diagnosis and management strategies in patients with coexistence of anemia and MS.

Fibroblast heterogeneity and tertiary lymphoid tissues in the kidney

Fibroblasts reside in various organs and support tissue structure and homeostasis under physiological conditions. Phenotypic alterations of fibroblasts underlie the development of diverse pathological conditions, including organ fibrosis. Recent advances in single‐cell biology have revealed that fibroblasts comprise heterogeneous subpopulations with distinct phenotypes, which exert both beneficial and detrimental effects on the host organs in a context‐dependent manner. In the kidney, phenotypic alterations of resident fibroblasts provoke common pathological conditions of chronic kidney disease (CKD), such as renal anemia and peritubular capillary loss. Additionally, in aged injured kidneys, fibroblasts provide functional and structural supports for tertiary lymphoid tissues (TLTs), which serve as the ectopic site of acquired immune reactions in various clinical contexts. TLTs are closely associated with aging and CKD progression, and the developmental stages of TLTs reflect the severity of renal injury. In this review, we describe the current understanding of fibroblast heterogeneity both under physiological and pathological conditions, with special emphasis on fibroblast contribution to TLT formation in the kidney. Dissecting the heterogeneous characteristics of fibroblasts will provide a promising therapeutic option for fibroblast‐related pathological conditions, including TLT formation.

Visual Outcomes of Adding Erythropoietin to Methylprednisolone for Treatment of Retrobulbar Optic Neuritis

PURPOSE

To compare the short-term visual function results and safety of erythropoietin as an add-on to the standard corticosteroid therapy in retrobulbar optic neuritis (RON).

METHODS

In this prospective pilot study, adult patients with isolated RON with less than 10 days of onset were enrolled. Patients were consecutively assigned to standard intravenous methylprednisolone treatment either in combination with intravenous erythropoietin (20,000 units/day for three days) (group-1) or intravenous methylprednisolone alone (group-2). Primary outcome measure was best-corrected visual acuity (BCVA), which was assessed up to 120 days from the day the treatment was begun. Systemic evaluations were performed during and after treatment.

RESULTS

Sixty-two patients with RON (mean age = 26.6 ± 5.77 years; range = 18-40 years) were enrolled into the study (group-1, n = 35; group-2, n = 27). BCVA three months after the treatment was 0.19 ± 0.55 logMAR and 0.11 ± 0.32 logMAR in group-1 and group-2, respectively (95% CI: - 0.61 - 0.16; P = 0.62). Change in BCVA after three months was 2.84 ± 3.49 logMAR in group-1 and 2.46 ± 1.40 logMAR in group-2 (95% CI: - 0.93 - 1.91; P = 0.57). Pace of recovery was not significantly different between the groups. No complications were detected among patients.

CONCLUSION

Intravenous erythropoietin as an add-on did not significantly improve the visual outcome in terms of visual acuity, visual field, and contrast sensitivity compared to traditional intravenous corticosteroid. This pilot study supports the safety profile of intravenous human recombinant erythropoietin, and it may help formulate future investigations with a larger sample size.

Effect of Moderate Hepatic Impairment on the Pharmacokinetics and Pharmacodynamics of Roxadustat, an Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor

BACKGROUND AND OBJECTIVE

Roxadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor in phase III development for the treatment of anaemia associated with chronic kidney disease. This study evaluated the effects of moderate hepatic impairment on roxadustat pharmacokinetics, pharmacodynamics and tolerability.

METHODS

This was an open-label study in which eight subjects with moderate hepatic impairment (liver cirrhosis Child-Pugh score 7-9) and eight subjects with normal hepatic function (matched for body mass index, age and sex) received a single oral 100 mg roxadustat dose under fasted conditions. Blood samples were collected until 144 h post-dose in subjects with moderate hepatic impairment and until 96 h post-dose in subjects with normal hepatic function.

RESULTS

In subjects with moderate hepatic impairment, area under the concentration-time curve (AUC) from the time of drug administration to infinity (AUC∞) and observed maximum concentration (C max) were 23 % higher [geometric least-squares mean ratio (GMR) 123 %; 90 % CI 86.1-175] and 16 % lower (GMR 83.6 %; 90 % CI 67.5-104), respectively, than in subjects with normal hepatic function. Mean terminal half-life (t ½) appeared to be longer (17.7 vs. 12.8 h) in subjects with moderate hepatic impairment, however intersubject variability on apparent total systemic clearance after single oral dosing (CL/F), apparent volume of distribution at equilibrium after oral administration (V z/F) and t ½ was approximately twofold higher. Erythropoietin (EPO) baseline-corrected AUC from administration to the last measurable EPO concentration (AUCE,last) and maximum effect (E max) were 31 % (GMR 68.95 %; 90 % CI 29.29-162.29) and 48 % (GMR 52.29 %; 90 % CI 28.95-94.46) lower, respectively, than in subjects with normal hepatic function. The single oral roxadustat dose was generally well tolerated.

CONCLUSIONS

This study demonstrated the effect of moderate hepatic impairment on the pharmacokinetics and pharmacodynamics of roxadustat relative to subjects with normal hepatic function. These differences are not expected to be of clinical significance.

Carbamylated Erythropoietin Outperforms Erythropoietin in the Treatment of AKI-on-CKD and Other AKI Models

Erythropoietin (EPO) may be a beneficial tissue-protective cytokine. However, high doses of EPO are associate with adverse effects, including thrombosis, tumor growth, and hypertension. Carbamylated erythropoietin (CEPO) lacks both erythropoietic and vasoconstrictive actions. In this study, we compared the renoprotective, hemodynamic, and hematologic activities and survival effects of identical EPO and CEPO doses in rat models of clinically relevant AKI presentations, including ischemia-reperfusion-induced AKI superimposed on CKD (5000 U/kg EPO or CEPO; three subcutaneous injections) and ischemia-reperfusion-induced AKI in old versus young animals and male versus female animals (1000 U/kg EPO or CEPO; three subcutaneous injections). Compared with EPO therapy, CEPO therapy induced greater improvements in renal function and body weight in AKI on CKD animals, with smaller increases in hematocrit levels and similarly improved survival. Compared with EPO therapy in the other AKI groups, CEPO therapy induced greater improvements in protection and recovery of renal function and survival, with smaller increases in systolic BP and hematocrit levels. Overall, old or male animals had more severe loss in kidney function and higher mortality rates than young or female animals, respectively. Notably, mRNA and protein expression analyses confirmed the renal expression of the heterodimeric EPO receptor/CD131 complex, which is required for the tissue-protective effects of CEPO signaling. In conclusion, CEPO improves renal function, body and kidney weight, and survival in AKI models without raising hematocrit levels and BP as substantially as EPO. Thus, CEPO therapy may be superior to EPO in improving outcomes in common forms of clinical AKI.

Early versus delayed erythropoietin for the anaemia of end-stage kidney disease

BACKGROUND

Anaemia is a common complication in people with chronic kidney disease (CKD) and mainly develops as a consequence of relative erythropoietin (EPO) deficiency. Anaemia develops early in the course of disease and peaks among people with end-stage kidney disease (ESKD). Many types of EPO - also called erythropoiesis-stimulating agents (ESAs) - are used to treat anaemia in people with ESKD.ESAs have changed treatment of severe anaemia among people with CKD by relieving symptoms and avoiding complications associated with blood transfusion. However, no benefits have been found in relation to mortality rates and non-cardiac fatal events, except quality of life. Moreover, a relationship between ESA use and increased cardiovascular morbidity and mortality in patients with CKD has been reported in studies with fully correcting anaemia comparing with partial anaemia correction. Until 2012, guidelines recommended commencing ESA treatment when haemoglobin was less than 11 g/dL; the current recommendation is EPO commencement when haemoglobin is between 9 and 10 g/dL. However, advantages in commencing therapy when haemoglobin levels are greater than 10 g/dL but less than 11 g/dL remain unknown, especially among older people whose life expectancy is limited, but in whom EPO therapy may improve quality of life.

OBJECTIVES

To assess the clinical benefits and harms of early versus delayed EPO for anaemia in patients with ESKD undergoing haemodialysis or peritoneal dialysis

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 8 July 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) and quasi-RCTs evaluating at the clinical benefits and harms of early versus delayed EPO for anaemia in patients with ESKD undergoing haemodialysis or peritoneal dialysis. Studies comparing EPO with another EPO, placebo or no treatment were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

It was planned that two authors would independently extract data from included studies and assess risk of bias using the Cochrane risk of bias tool. For dichotomous outcomes (all-cause mortality, cardiovascular mortality, overall myocardial infarction, overall stroke, vascular access thrombosis, adverse effects of treatment, transfusion), we planned to use the risk ratio (RR) with 95% confidence intervals (CI). We planned to calculate the mean difference (MD) and CI 95% for continuous data (haemoglobin level) and the standardised mean difference (SMD) with CI 95% for quality of life if different scales had been used.

MAIN RESULTS

Literature searches yielded 1910 records, of these 1534 were screened after duplicates removed, of which 1376 were excluded following title and abstract assessment. We assessed 158 full text records and identified 18 studies (66 records) that were potentially eligible for inclusion. However, none matched our inclusion criteria and were excluded.

AUTHORS' CONCLUSIONS

We found no evidence to assess the benefits and harms of early versus delayed EPO for the anaemia of ESKD.

Benefits and risks of erythrocyte-stimulating agents

Chronic kidney disease (CKD) is a common and serious clinical problem. Anemia in patients with advanced CKD, frequently called renal anemia, causes disabling fatigue and diminishes patients’ quality of life. Frequent and excess transfusions or iron supplementation are potentially hazardous. Although it remains unclear whether the main factor in the development of renal anemia is the failure of erythropoietin (EPO) production in the kidney or a dysfunction in oxygen sensing exogenous EPO administration is considered a rational treatment. The advent of recombinant human erythropoietin (rHu-EPO) products has dramatically changed the therapeutic strategy for renal anemia. Although rHu-EPO therapy has improved patients’ quality of life and decreased the need for blood transfusions, some potential adverse effects have been reported till date. This brief review discusses the treatment of renal anemia with regard to the following: (1) historical background; (2) effectiveness of rHu-EPO; (3) some topics regarding the treatment of anemia, including EPO resistance, hemoglobin (Hb) cycling, and adequate Hb levels; (4) major adverse effects of rHu-EPO, including hypertension, thrombotic complications, and pure red cell aplasia; and (5) future problems to be resolved.

Renal anemia: from incurable to curable

Renal anemia has been recognized as a characteristic complication of chronic kidney disease. Although many factors are involved in renal anemia, the predominant cause of renal anemia is a relative deficiency in erythropoietin (EPO) production. To date, exogenous recombinant human (rh)EPO has been widely used as a powerful drug for the treatment of patients with renal anemia. Despite its clinical effectiveness, a potential risk for increased mortality has been suggested in patients who receive rhEPO, in addition to the economic burden of rhEPO administration. The induction of endogenous EPO is another therapeutic approach that might have advantages over rhEPO administration. However, the physiological and pathophysiological regulation of EPO are not fully understood, and this lack of understanding has hindered the development of an endogenous EPO inducer. In this review, we will discuss the current treatment for renal anemia and its drawbacks, provide an overview of EPO regulation in healthy and diseased conditions, and propose future directions for therapeutic trials that more directly target the underlying pathophysiology of renal anemia.

Targeting erythropoietin for chronic neurodegenerative diseases

INTRODUCTION

Since erythropoietin (EPO) and EPO receptor (EPOR) are expressed in the central nervous system (CNS) beyond hematopoietic system, EPO illustrates a robust biological function in maintaining neuronal survival and regulating neurogenesis and may play a crucial role in neurodegenerative diseases.

AREAS COVERED

EPO is capable of modulating multiple cellular signal transduction pathways to promote neuronal survival and enhance the proliferation and differentiation of neuronal progenitor cells. Initially, EPO binds to EPOR to activate the Janus-tyrosine kinase 2 (Jak2) protein followed by modulation of protein kinase B (Akt), mammalian target of rapamycin, signal transducer and activators of transcription 5, mitogen-activated protein kinases, protein tyrosine phosphatases, Wnt1 and nuclear factor κB. As a result, EPO may actively prevent the progression of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis and motor neuron diseases.

EXPERT OPINION

Novel knowledge of the cell signaling pathways regulated by EPO in the CNS will allow us to establish the foundation for the development of therapeutic strategies against neurodegenerative diseases. Further investigation of the role of EPO in neurodegenerative diseases can not only formulate EPO as a therapeutic candidate, but also further identify novel therapeutic targets for these disorders.

Arterial hypertension induced by erythropoietin and erythropoiesis-stimulating agents (ESA)

This review summarizes the evidence for a hypertensinogenic effect of Erythropoietin (Epo) in normal human subjects and predialysis, hemodialysis, and continuous ambulatory peritoneal dialysis (CAPD) patients. The possible mechanisms of Epo-induced hypertension are examined with in vivo animal and in vitro data, as well as pathophysiological human studies in both normal subjects and CKD patients. The evidence for a hypertensinogenic effect of erythropoiesis-stimulating agents (ESAs) in normal subjects, predialysis CKD, hemodialysis, and CAPD patients is compelling. Epo increases BP directly and notably independently of its erythropoietic effect and its effect on blood rheology. The potential for the development of future agents that might act as specific stimulators of erythropoiesis, devoid of direct hemodynamic side effects is underscored.

Low testosterone and anaemia in men with type 2 diabetes

OBJECTIVE

Anaemia is frequently found in patients with diabetes, in whom it is associated with increased morbidity and mortality. Low testosterone levels are also common in men with type 2 diabetes. We hypothesized that low testosterone levels are also associated with anaemia in men with type 2 diabetes, over the effects of chronic kidney disease.

DESIGN

Cross-sectional cohort study, performed in 2005 in a tertiary diabetes clinic. Patients 464 men with type 2 diabetes.

MAIN OUTCOME MEASURE

Anaemia (haemoglobin (Hb) < 13.7 g/dl in men aged < 60, or < 13.2 g/dl in men aged 60 and older).

RESULTS

About 24% of study participants had anaemia, which was associated with the presence and severity of chronic kidney disease, systemic inflammation, increased age, and reduced iron availability. In addition, testosterone levels were independently associated with reduced Hb levels, determining between 6 and 8% of the total variability in raw Hb levels in this population after adjusting for these other factors. Individuals with total testosterone level < 10 nmol/l (43% of the cohort) were more likely to have anaemia (adjusted odds ratio 1.7; 95% CI 1.1-2.8). Similarly, anaemia was twice as common in individuals with a calculated free testosterone of < 0.23 nmol/l (adjusted odds ratio 2.0, 95% CI 1.2-3.1).

CONCLUSIONS

These findings suggest that testosterone deficiency may contribute to the increased frequency of anaemia in men with type 2 diabetes. However, the appropriate clinical response to testosterone deficiency in anaemic patients remains to be established by prospective clinical trials.

Anemia and anemia correction: surrogate markers or causes of morbidity in chronic kidney disease?

Observational studies have shown a strong positive correlation between the severity of anemia and the risk of poor outcomes in patients with chronic kidney disease (CKD). This observation was initially taken to imply that adverse outcomes in CKD are caused by anemia. However, the assumption of causality ignores the possibility that anemia and adverse outcomes might be unrelated and that both are caused by underlying inflammation, oxidative stress and comorbid conditions. Randomized clinical trials of anemia correction have revealed an increased risk of adverse cardiovascular outcomes in patients assigned to normal, rather than subnormal, hemoglobin targets. As a result, correction of anemia is now considered potentially hazardous in patients with CKD. Notably, individuals who did not reach the target hemoglobin level in the clinical trials, despite receiving high doses of erythropoietin and iron, experienced a disproportionately large share of the adverse outcomes. These observations point to overdose of erythropoietin and iron, rather than anemia correction per se, as the likely culprit. This Review explores the reasons for the apparent contradiction between the findings of observational studies and randomized clinical trials of anemia treatment in CKD. I have focused on data from basic and translational studies, which are often overlooked in the design and interpretation of clinical studies and in the formulation of clinical guidelines.

Anemia of Chronic Kidney Disease

Chronic kidney disease may result in complete kidney failure and contribute to many other health issues. Anemia is a logical consequence of the disease because the kidneys are the primary source of erythropoietin, the hormone that acts to stimulate red blood cell production in the bone marrow. All patients with chronic kidney disease are at risk for anemia, and treating anemia is extremely important to their health and well-being. Preventing or reversing the effects of anemia on the heart may decrease morbidity and mortality and improve quality of life. Many patients fail to receive treatment for anemia before requiring renal replacement therapy for end-stage renal disease. Pharmacists can play a vital role in screening, evaluating, designing proper treatment regimens, and monitoring patients with anemia of chronic kidney disease. Current recommendations regarding anemia are reviewed, including evaluation, pharmacotherapeutic agents, monitoring parameters, and goals of therapy.

Erythropoietin pharmacology

Anaemia is a frequent complication in cancer patients and may be multifactorial in origin. Treatment with recombinant human erythropoietin (rHuEPO) is an alternative to red blood cell transfusion. The evidence from clinical trials has established that patients with chemotherapy-induced anaemia with a haemoglobin concentration below 10 g/dl benefit from epoetin therapy. The native glycoprotein hormone consists of 165 amino acids with three N-glycosylation and one O-glycosylation sites. Epoetin and darbepoetin bind to the EPO receptor to induce intracellular signalling by the same intracellular molecules as native EPO. There are some differences in the glycosylation pattern which lead to variations in the pharmacokinetics and pharmacodynamics profiles. Pharmacokinetic and therapeutic studies have examined the use of rHuEPO administered intravenously and subcutaneously and there is accumulating evidence that the latter route has several advantages in cancer patients. After subcutaneous administration, the bioavailability of epoetin is about 20-30% and has a plasma half-life of >24 h. Darbepoetin has a longer half-life after subcutaneous administration of 48 h. The general recommendations are based on evidence from trials in which epoetin was administered 150 U/kg thrice weekly. The recommended initial dose for darbepoetin alpha is 2.25 mug/kg per week. The most serious adverse effects are hypertension, bleeding and increased risk of thrombotic complications. Caution is advised when used in patients who are at high risk for thromboembolic events. In the management of anaemic cancer patients, physicians should closely follow the National Comprehensive Cancer Network (NCCN) and American Society of Clinical Oncology (ASCO)/American Society of Hematology (ASH) guidelines.

Oxygen delivery enhancers: past, present, and future

In endurance sport the delivery of oxygen to muscles plays a critical role. Indeed, muscle performance declines during prolonged and intense activity as a consequence of the shift from the aerobic to the anaerobic metabolism with an increase of lactate. To enhance the aerobic capacity 2 alternatives may be used: increasing either the transport or the delivery of oxygen. In this setting, blood doping is the practice of illicitly using a drug or blood product to improve athletic performance. Based on this definition, blood doping techniques may include: 1) blood transfusion (autologous or omologous); 2) erythropoiesis-stimulating substances [recombinant human erythropoietin (alpha, beta, omega), darbepoietin-alpha, continuous erythropoiesis receptor activator, hematide]; 3) blood substitutes (hemoglobin-based oxygen carriers, perfluorocarbon emulsions); 4) allosteric modulators of hemoglobin (RSR-13 and RSR-4); 5) gene doping (human erythropoietin gene transfection); 6) gene regulation (hypoxia-inducible transcription factors pathway). In the present overview we will briefly describe the above-mentioned techniques with the aim of underlining potential hematological alternatives to gene doping for increasing aerobic capacity in sport.

Reducing versus discontinuing erythropoietin at high hemoglobin levels

A 2006 change in Medicare policy allowed reimbursement for erythropoietin (EPO) in dialysis patients whose most recent hemoglobin exceeded 13 g/dl. We investigated the effects of a change in dosing algorithm implemented in response to this policy, in which EPO dosages were reduced instead of temporarily discontinued for hemoglobin levels > or =13 g/dl. Among 1688 individuals in 18 hemodialysis units, the reduction protocol resulted in more hemoglobin levels > or =13 g/dl (P < 0.0001), fewer levels between 11 and 12.9 g/dl (P < or = 0.004), no difference in the proportion of levels <11 g/dl, and more EPO administered per session (P < 0.0001) than the discontinuation protocol. In view of the expense of erythropoiesis stimulating agents and the uncertainty of the safety of using EPO to achieve high hemoglobin targets, this study suggests that discontinuation, rather than reduction, of EPO treatment is appropriate when hemoglobin reaches 13 g/dl in hemodialysis patients.

Anemia in diabetes: marker or mediator of microvascular disease?

Anemia is a common finding in patients with diabetes due to the high burden of chronic kidney disease in this population. Anemia is more prevalent and is found earlier in patients with diabetes than in those with kidney disease from other causes. The increased risk of anemia in diabetes probably reflects changes in the renal tubulointerstitium associated with diabetic kidney disease, which disrupt the delicate interaction between interstitial fibroblasts, capillaries and tubular cells required for normal hemopoietic function. In particular, the uncoupling of the hemoglobin concentration from renal erythropoietin synthesis seems to be the key factor underlying the development of anemia. Systemic inflammation, functional hematinic deficiencies, erythropoietin resistance and reduced red cell survival also drive anemia in the setting of impaired renal compensation. Although anemia can be considered a marker of kidney damage, reduced hemoglobin levels independently identify diabetic patients with an increased risk of microvascular complications, cardiovascular disease and mortality. Nevertheless, a direct role in the development or progression of diabetic complications remains to be clearly established and the clinical utility of correcting anemia in diabetic patients has yet to be demonstrated in randomized controlled trials. Correction of anemia certainly improves performance and quality of life in diabetic patients. In the absence of additional data, treatment should be considered palliative, and any functional benefits must be matched against costs to the patient and the health system.