Recommendations on haematological criteria for the diagnosis of epoetin-induced pure red cell aplasia

UK kidney association clinical practice guideline: update of anaemia of chronic kidney disease

Anaemia is common in chronic kidney disease (CKD) encompassing non-dialysis dependent CKD (NDD-CKD) and dialysis dependent CKD (DD-CKD); people on peritoneal dialysis (PD) and haemodialysis (HD); and kidney transplant recipients (KTR). Iron deficiency and erythropoietin deficiency are the most common causes of anaemia in people with CKD, especially those requiring kidney replacement therapy (KRT). The Renal National Service Framework and National Institute for Health and Clinical Excellence in the UK, and Kidney Disease Improving Global Outcomes (KDIGO), all advocate treatment of anaemia in people with CKD. Blood transfusions are infrequently required, and newer therapies such as Hypoxia-Inducible Factor (HIF-PHI) stabilisers are now in current use. This guideline provides evidence based graded practice guidance on the use of iron; comments on iron deficiency without anaemia in people with CKD; provide further information on anaemia management in people with a transplant and provide guidance in the use of the new HIF-PHI drugs. It also provides audit and research recommendations.

Mutational heterogeneities in STAT3 and clonal hematopoiesis-related genes in acquired pure red cell aplasia

Dysregulation of T cell-mediated immunity is considered a major pathophysiological mechanism in acquired pure red cell aplasia (PRCA), including idiopathic PRCA, large granular lymphocytic leukemia-associated PRCA, and thymoma-associated PRCA. Although STAT3 mutations are frequently detected in PRCA patients, the roles of other mutational profiles and their impact on clinical characteristics remain unclear. In this study, whole-exome sequencing and targeted sequencing using a custom-designed panel were performed on 53 PRCA patients. The most frequently mutated genes were STAT3 (36%), PCLO (9%), TET2 (9%), NEB (6%), DNMT3A (6%), and POT1 (6%). Based on genetic profiles, patients were classified into three groups: those with STAT3 variants (group S), those without STAT3 variants but with variants in clonal hematopoiesis (CH)-related genes (group C), and those without variants in either STAT3 or CH-related genes (group O). Patients in group O had a higher median age compared to group S, while group S exhibited milder anemia severity than group C. Additionally, POT1 variants were associated with the idiopathic subtype of PRCA in females, often co-occurring with STAT3 variants. Variants in CH-related genes and other genes, including STAT3 and POT1, may play crucial roles in the pathophysiology of PRCA.

EPO-Mimetic Peptide Pegmolesatide Therapy for Pure Red Cell Aplasia in a Patient with Non-dialysis-dependent Type 1 Diabetic Nephropathy: A Case Report

Pure red cell aplasia (PRCA) is a rare complication of erythropoietin (EPO) therapy, characterized by a severe deficiency in red blood cell production. There is no guideline on the treatment for PRCA because there have been too few cases to perform prospective cohort studies. The main treatments for PRCA include immediate cessation of EPO, restrictive transfusion, and immunosuppressive therapies. A 35-year-old male patient with type 1 diabetic nephropathy was diagnosed with PRCA. Enarodustat and roxadustat were administered successively after discontinuation of EPO, but anemia did not improve, and the patient was maintained with weekly blood transfusions. Subsequently, the EPO-mimetic peptide pegmolesatide was administered, and the patient's hemoglobin started to increase after 1 week and increased from 50 g/L to 92 g/L over approximately 3 months. Based on these findings, we speculate that pegmolesatide can provide a safe, effective, and convenient therapeutic strategy for PRCA in Chinese patients with chronic kidney disease.

Bone Marrow Findings in Renal Patients: A Single Renal Specialist Center Experience

Objective

This study evaluated the importance of bone marrow aspiration and trephine biopsy (BM) for the diagnosis of underlying hematological abnormalities in renal patients.

Methods

This cross-sectional study on BM was carried out between August 2010 and April 2019, in our specialist renal center for various unexplained hematological abnormalities in patients with renal diseases [chronic kidney disease (CKD), end-stage renal disease (ESRD) requiring maintenance hemodialysis (MHD), patients with normal renal function but other nephrology and urology issues like stone disease and nephrotic syndrome].

Results

Out of 176 reported BM examinations, 48 (27.3%) were done on ESRD patients on MHD (CKD-D), and 69 (39.2%) on CKD patients not on MHD (CKD-nD). Fifty-nine (33.5%) BM were done on patients with normal renal function (n-CKD). The indication for BM was pancytopenia 50 (28.4%), unexplained anemia 39 (22.2%), and unexplained thrombocytopenia 43 (24.4%). In 91 (51.7%) patients BM was normal. In 30 (17%) patients multiple myeloma (MM) was diagnosed on BM, out of which 18 (26.1%), nine (18%), three (5.3%) were CKD-nD, CKD-D, and n-CKD patients, respectively. In 11 (6.3%) patients BM was suggestive of myelodysplasia (MD), out of these 11 patients, five (10%) were CKD-D patients.

Conclusion

BM is an underutilized method of diagnosis of hematological abnormalities in renal patients. Our study revealed the importance of BM examination, especially in patients with CKD.

Roxadustat Improves Erythropoietin Antibody-Mediated Pure Red Cell Aplasia in a Patient with Hemodialysis

Anemia is a common complication of chronic kidney disease (CKD). Recombinant human erythropoietin (rHu-EPO) is used extensively in patients with CKD. However, anti-erythropoietin (anti-EPO) antibody has been reported during rHu-EPO treatment, which causes pure red cell aplasia (PRCA). We presented a case of 75-year-old man, who underwent hemodialysis for 2 years. He developed PRCA during rHu-EPO treatment. The rHu-EPO was immediately discontinued, and the patient was given roxadustat treatment. After 6 months of roxadustat treatment, the anti-EPO antibody was disappeared, and hemoglobin recovered normal range. The results suggest that roxadustat can be used to treat patients with anti-EPO antibody-mediated PRCA without immunosuppressive therapy.

Acquired Pure Red Cell Aplasia and Recombinant Erythropoietin

Recombinant erythropoietin (rEPO)-associated immunologically driven acquired pure red cell aplasia (PRCA) is an underreported, potentially worsening clinical syndrome in the setting of treatment of anemia of chronic kidney disease. Most cases reported in world literature are related to different formulations of erythropoiesis-stimulating agents with an implication in diagnosis and management. This brief review highlights the clinical guidelines of rEPO usage in nephrology practice, the pathophysiologic mechanism of PRCA, clinical features, diagnosis, and suggested management protocols.

Management of thymoma associated autoimmune pure red cell aplasia: Case report and systematic review of the literature

Pure red cell aplasia (PRCA) is a rare paraneoplastic syndrome observed in 2-5 % of thymomas. Literature reports great variability in its management. Based on an illustrative clinical case, we present a systematic literature review whose main objective is to evaluate the therapeutic management of PRCA. The literature search was performed based on the PICO method in the Medline and Scopus databases. The reference clinical case concerns a 51-year-old woman with stage IVa thymoma. After initial response to chemotherapy, a locoregional progression occurred with PRCA development that responded favorably under second line chemotherapy. The patient finally died in a context of bicytopenia with febrile neutropenia. The systematic review covers 135 articles published between 1950 and 2019. Thymectomy alone or in combination with other therapies showed a 31 % complete remission (CR) rate for PRCA of, whereas none was reported with anti-tumor treatments without thymectomy. Among immunomodulatory therapies, cyclosporin gave the highest percentage of CR (74 %). Finally, the combination of thymectomy and immunomodulatory treatments showed a CR rate of 45 %. Thymectomy appeared to be the most effective anti-tumor treatment for PRCA. Immunomodulatory therapies, particularly cyclosporine, are shown effective, but the risk of infectious complications must be considered. The optimal place of anti-tumor and immunomodulatory therapies against PRCA has yet to be determined.

Acquired Pure Red Cell Aplasia Following Recombinant Erythropoietin (Darbepoetin-alfa) Therapy

Acquired pure red cell aplasia (PRCA) following use of recombinant erythropoietin (rEPO) is distinctly rare and sporadically reported in the literature. We discuss a case of PRCA following the usage of rEPO (darbepoetin-α) during the management of anemia of chronic kidney disease in an elderly male subject with review of literature and a brief insight into proposed pathophysiologic mechanism, diagnosis, and management.

Frequent STAT3 mutations in CD8+ T cells from patients with pure red cell aplasia

Dysregulation of T-cell-mediated immunity is responsible for acquired pure red cell aplasia (PRCA). Although STAT3 mutations are frequently detected in patients with T-cell large granular lymphocytic leukemia (T-LGLL), which is often complicated by PRCA and which is also reported to be associated with acquired aplastic anemia (AA) and myelodysplastic syndrome (MDS), whether STAT3-mutated T cells are involved in the pathophysiology of PRCA and other types of bone marrow failure remains unknown. We performed STAT3 mutation analyses of the peripheral blood mononuclear cells from PRCA patients (n = 42), AA (n = 54), AA-paroxysmal nocturnal hemoglobinuria (AA-PNH; n = 7), and MDS (n = 21) using an allele-specific polymerase chain reaction and amplicon sequencing. STAT3 mutations were not detected in any of the 82 patients with AA/PNH/MDS but were detected in 43% of the 42 PRCA patients. In all 7 STAT3-mutation-positive patients who were studied, the STAT3 mutations were restricted to sorted CD8⁺ T cells. The prevalence of STAT3 mutation in idiopathic, thymoma-associated, autoimmune disorder-associated, and T-LGLL-associated PRCA was 33% (5 of 15), 29% (2 of 7), 20% (1 of 5), and 77% (10 of 13), respectively. The STAT3-mutation-positive patients were younger (median age, 63 vs 73 years; P= .026) and less responsive to cyclosporine (46% [6 of 13] vs 100% [8 of 8]; P= .0092) in comparison with STAT3-mutation-negative patients. The data suggest that STAT3-mutated CD8⁺ T cells may be closely involved in the selective inhibition of erythroid progenitors in PRCA patients.

Renal association clinical practice guideline on Anaemia of Chronic Kidney Disease

Anaemia is a commonly diagnosed complication among patients suffering with chronic kidney disease. If left untreated, it may affect patient quality of life. There are several causes for anaemia in this patient population. As the kidney function deteriorates, together with medications and dietary restrictions, patients may develop iron deficiency, resulting in reduction of iron supply to the bone marrow (which is the body organ responsible for the production of different blood elements). Chronic kidney disease patients may not be able to utilise their own body's iron stores effectively and hence, many patients, particularly those receiving haemodialysis, may require additional iron treatment, usually provided by infusion.With further weakening of kidney function, patients with chronic kidney disease may need additional treatment with a substance called erythropoietin which drives the bone marrow to produce its own blood. This substance, which is naturally produced by the kidneys, becomes relatively deficient in patients with chronic kidney disease. Any patients will eventually require treatment with erythropoietin or similar products that are given by injection.Over the last few years, several iron and erythropoietin products have been licensed for treating anaemia in chronic kidney disease patients. In addition, several publications discussed the benefits of each treatment and possible risks associated with long term treatment. The current guidelines provide advice to health care professionals on how to screen chronic kidney disease patients for anaemia, which patients to investigate for other causes of anaemia, when and how to treat patients with different medications, how to ensure safe prescribing of treatment and how to diagnose and manage complications associated with anaemia and the drugs used for its treatment.

A cluster of Epoetin-associated pure red cell aplasia: clinical features and the possible association of HLA-DRB1*12:02

Antibody-mediated pure red cell aplasia is a rare but serious complication in chronic kidney disease patients receiving recombinant human erythropoietin (r-HuEpo). Between April 2012 and May 2013, eight such cases were reported in our institution. Their clinical features were reviewed and their HLA alleles were compared with those of healthy controls. All patients were exposed to epoetin alfa (Eprex^®) with polysorbate-80 as stabilizer via subcutaneous route with a mean age of 61.9 years and mean exposure of 11.2 months of r-HuEpo before loss of efficacy. 87.5% of the cases were male and Chinese and received immunosuppression as treatment for pure red cell aplasia. All three of the successfully treated patients are alive compared with only 40% of the transfusion-dependent patients. DRB1*12:02 was more frequently expressed among the cases than healthy controls suggesting a plausible molecular link.

Anti-Erythropoietin Antibody Associated Pure Red Cell Aplasia Resolved after Liver Transplantation

Patients undergoing antiviral therapy for chronic hepatitis C often develop anemia secondary to ribavirin and interferon. Recombinant erythropoietin has been used to improve anemia associated with antiviral therapy and to minimize dose reductions, which are associated with decreased rates of sustained virologic response. A rare potential side effect of recombinant erythropoietin is anti-erythropoietin antibody associated pure red cell aplasia. In chronic kidney disease patients with this entity, there have been good outcomes associated with renal transplant and subsequent immunosuppression. In this case, a chronic liver disease patient developed anti-erythropoietin associated pure red cell aplasia and recovered after liver transplantation and immunosuppression. It is unclear whether it is the transplanted organ, the subsequent immunosuppression, or the combination that contributed to the response. In conclusion, anti-erythropoietin associated pure red cell aplasia is a serious complication of erythropoietin therapy, but this entity should not be considered a contraindication for solid organ transplantation.

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.

Risk of pure red cell aplasia in patients with hepatitis C receiving antiviral therapy and an erythropoiesis-stimulating agent

Antibody-mediated pure red cell aplasia (PRCA) has been primarily observed in patients with chronic kidney disease treated with an erythropoiesis-stimulating agent (ESA); only a few anecdotal cases have been reported in other patient populations. We searched the Amgen Global Safety Adverse Event Database and identified 14 patients with hepatitis C who developed severe anemia, anti-erythropoietin antibodies, and bone marrow biopsy-proven PRCA, while receiving interferon therapy (with or without ribavirin) and an ESA. During the follow-up period and after ESA treatment stopped, 11 patients no longer required transfusions and 3 did. Analysis of antibody isotypes showed that, contrary to reports of patients with chronic kidney disease, immunoglobulin G1 was the predominant isotype rather than immunoglobulin G4 (immunoglobulin G4 was detected in only 1 of 6 patients). Epitope mapping showed the anti-erythropoietin antibodies bound domains required for receptor binding. Therefore, the potential benefits of ESA therapy must be weighed against the risk for PRCA in patients with hepatitis C who are receiving treatment with interferon and ribavirin.

Erythropoietin doping in cycling: lack of evidence for efficacy and a negative risk-benefit

Imagine a medicine that is expected to have very limited effects based upon knowledge of its pharmacology and (patho)physiology and that is studied in the wrong population, with low-quality studies that use a surrogate end-point that relates to the clinical end-point in a partial manner at most. Such a medicine would surely not be recommended. The use of recombinant human erythropoietin (rHuEPO) to enhance performance in cycling is very common. A qualitative systematic review of the available literature was performed to examine the evidence for the ergogenic properties of this drug, which is normally used to treat anaemia in chronic renal failure patients. The results of this literature search show that there is no scientific basis from which to conclude that rHuEPO has performance-enhancing properties in elite cyclists. The reported studies have many shortcomings regarding translation of the results to professional cycling endurance performance. Additionally, the possibly harmful side-effects have not been adequately researched for this population but appear to be worrying, at least. The use of rHuEPO in cycling is rife but scientifically unsupported by evidence, and its use in sports is medical malpractice. What its use would have been, if the involved team physicians had been trained in clinical pharmacology and had investigated this properly, remains a matter of speculation. A single well-controlled trial in athletes in real-life circumstances would give a better indication of the real advantages and risk factors of rHuEPO use, but it would be an oversimplification to suggest that this would eradicate its use.

Measurement of anti-erythropoiesis-stimulating agent IgG4 antibody as an indicator of antibody-mediated pure red cell aplasia

Patients treated with erythropoietin-based erythropoiesis-stimulating agents (ESAs) can develop a rare but life-threatening condition called antibody-mediated pure red cell aplasia (amPRCA). The antibody characteristics in a nephrology patient with amPRCA include high antibody concentrations with neutralizing activity and a mixed IgG subclass including anti-ESA IgG4 antibodies. In contrast, anti-ESA IgG4 antibody is generally not detected in baseline samples and antibody-positive non-PRCA patients. Therefore, we validated a highly sensitive immunoassay on the ImmunoCAP 100 instrument to quantitate anti-ESA IgG4 antibodies using a human recombinant anti-epoetin alfa (EPO) IgG4 antibody as a calibrator. The biotinylated ESA was applied to a streptavidin ImmunoCAP, and bound anti-ESA IgG4 antibodies were detected using a β-galactosidase-conjugated mouse anti-human IgG4 antibody. The validated assay was used to detect anti-ESA IgG4 in amPRCA and non-PRCA patients. The immunoassay detected 15 ng/ml of human anti-EPO IgG4 antibody in the presence of a 200 M excess of human anti-ESA IgG1, IgG2, or IgM antibody and tolerated 2 μg/ml of soluble erythropoietin. All patient samples with confirmed amPRCA had measurable anti-ESA IgG4 antibodies. In addition, 94% (17/18) of non-PRCA patient samples were antibody negative or had below 15 ng/ml of anti-ESA IgG4 antibodies. This novel immunoassay can measure low-nanogram quantities of human anti-ESA IgG4 antibodies in the presence of other anti-ESA antibodies. An increased concentration of anti-ESA IgG4 antibody is associated with the development of amPRCA. We propose that the measurement of anti-ESA specific IgG4 antibodies may facilitate early detection of amPRCA in patients receiving all ESAs structurally related to human erythropoietin.

Pure red cell aplasia in a simultaneous pancreas-kidney transplantation patient: inside the erythroblast

A case of pure red cell aplasia in a simultaneous kidney-pancreas transplant recipient on immunosuppressive therapy is reported here. The patient presented with anemia unresponsive to erythropoietin treatment. Bone marrow cytomorphology was highly suggestive of parvovirus pure red cell aplasia, which was confirmed with serology and polymerase chain reaction positive for parvovirus B19 DNA in peripheral blood. After the administration of intravenous immunoglobulin the anemia improved with a rising number of the reticulocytes.

Clinical implications of initial renal function after deceased donor transplant

The aim of this study was to investigate whether slow graft function (SGF) after transplantation of deceased-donor kidneys affected the prevalence of anemia or the glomerular filtration rate (GFR). We retrospectively evaluated the records of 534 kidney transplant patients who were classified based on their initial renal function, namely, immediate graft function (IGF), slow graft function (SGF), or delayed graft function (DGF). Among the 534 kidney transplant patients studied, the occurrences of each condition were IGF 104, SGF 133, and DGF 297. Six months after transplantation, a greater percentage of DGF patients were anemic compared with the others (P = .028). However, at 12 months after transplantation, SGF patients showed more anemia than the IGF group. DGF and SGF patients displayed similar GFR values at 18 and 24 months after transplantation. However, IGF patients displayed higher GFRs, even when subjects who experienced acute rejection episodes were censored (P = .004). The incidence of acute rejection episodes was similar among SGF and DGF patients. Patients displaying SGF after deceased-donor transplantation showed a greater tendency to be anemic than those displaying IGF. This study also suggested that SGF patients were at risk for acute rejection episodes and/or significantly reduced kidney function as measured by GFR.

High avidity cytokine autoantibodies in health and disease: pathogenesis and mechanisms

Numerous reports have documented the presence of autoantibodies working against naturally occurring cytokines in humans in health and disease. In most instances, their physiological and pathophysiological significance remains unknown. However, recent advances in the methodologies for detecting cytokine autoantibodies and their application in research focused on specific disorders have shown that some cytokine autoantibodies play an important role in the pathogenesis of disease. Additionally, levels of cytokine autoantibodies may also correlate with disease severity and progression in certain infectious and autoimmune diseases but not in others. This suggests that cytokine-specific pathogenic differences exist. While multiple lines of evidence support the notion that high avidity cytokine autoantibodies are present and likely to be ubiquitous in healthy individuals, their potential physiological role, if any, is less clear. It is believed that they may function by scavenging pro-inflammatory cytokines and thereby inhibiting deleterious 'endocrine' effects, or by serving as carrier proteins, providing a 'reservoir' of inactive cytokines and thus modulating cytokine bioactivity. A central hypothesis is that sustained or repeated high-level exposure to cytokines triggers defects in T-cell tolerance, resulting in the expansion of existing cytokine autoantibody-producing B cells.

Therapeutic equivalence of epoetin zeta and alfa, administered subcutaneously, for maintenance treatment of renal anemia

INTRODUCTION

The primary objective of the trial was to prove the therapeutic equivalence of epoetin zeta to epoetin alfa when administered subcutaneously for maintaining target hemoglobin (Hb) in patients with renal anemia on chronic hemodialysis. Additional information was provided on the safety and tolerability of epoetin zeta with particular focus on the formation of anti-erythropoietin antibodies.

METHODS

A total of 462 patients were randomized to either epoetin zeta or alfa for 28 weeks after an open period of dose adjustment of 12-16 weeks with only epoetin zeta. The aim of treatment was to maintain Hb between 10.0-12.0 g/dL with constant epoetin dosage. Primary endpoints were the mean Hb level and the mean weekly epoetin dosage during the last 4 weeks of treatment. Safety endpoints were the occurrence of anti-erythropoietin antibodies, incidence of Hb levels above 13 g/dL, ratings of tolerability, and adverse events (AEs).

RESULTS

The mean Hb level (+/-SD) during the last 4 weeks of treatment was 10.94+/-0.84 g/dL (epoetin zeta) and 11.02+/-0.94 g/dL (epoetin alfa). The 95% confidence interval (CI) (''C0.28 g/dL to 0.12 g/dL) was entirely within the predefined equivalence range (+/-0.5 g/dL). The mean weekly epoetin dosage per body weight over the last 4 weeks of treatment was 97.0+/-94.3 IU/kg/week (epoetin zeta) and 86.0+/-78.0 IU/kg/week (epoetin alfa). The 95% CI (''C8.06 IU/kg/week to 29.96 IU/kg/week) was also within the predefined equivalence range of +/-45 IU/kg/week. The most common AEs were infections and infestations (15.1% of patients on epoetin zeta and 14.8% of patients on epoetin alfa). None of the patients developed anti-erythropoietin antibodies.

CONCLUSIONS

Epoetin zeta, administered subcutaneously, is equivalent to epoetin alfa in respect of its clinical efficacy. The safety profile of both products is similar: no unexpected AEs were observed, no patients developed anti-erythropoietin antibodies, and both epoetin preparations were well tolerated.

Isoniazid-triggered pure red cell aplasia in systemic lupus erythematosus complicated with myasthenia gravis

A 47-year-old woman who had been treated for systemic lupus erythematosus (SLE) with myasthenia gravis (MG) was admitted to our hospital with acute onset of severe anemia after administration of isoniazid. Pure red cell aplasia (PRCA) was confirmed by elevated serum iron levels, reticulocytopenia and bone marrow aspiration showing a remarkable reduction of erythroblasts. Finally, cyclosporine A successfully improved PRCA. Although both SLE and MG have the potential complication of PRCA, we report here a case of isoniazid-triggered PRCA.

Pure red cell aplasia as first manifestation of splenic marginal zone lymphoma-successful treatment with rituximab: a case report

Introduction

Acquired pure red cell aplasia is a rare disorder, usually appearing secondary to various pathologic conditions such as thymoma, systemic autoimmune diseases or in the course of lymphomas. Conventional treatment consists of immunosuppression with corticosteroids, antithymocyte globulin or cyclosporin-A.

Case presentation

8 weekly courses of rituximab were administered to a patient who presented with pure red cell aplasia secondary to newly diagnosed splenic marginal zone lymphoma. Transfusion independence was achieved after the 6^th course, and pure red cell aplasia receded completely with therapy.

Conclusion

Pure red cell aplasia may ensue early in the course of splenic marginal zone lymphoma and other low grade lymphomas. Rituximab is a safe and effective alternative treatment for pure red cell aplasia secondary to lymphoproliferative disorders.

Rituximab therapy for pure red cell aplasia due to anti-epoetin antibodies in a woman treated with epoetin-alfa: a case report

Introduction

Pure red cell aplasia due to anti-epoetin antibodies is a known complication of epoetin therapy for anemia due to chronic kidney disease. This disease has not previously been well described in the setting of therapy for chronic hepatitis C virus infection. While treatment for pure red cell aplasia due to anti-epoetin antibodies is usually with immunosuppressive therapy such as calcineurin inhibition, the safety of this treatment in chronic hepatitis C virus infection is unknown. To date, little has been published on the efficacy of rituximab on pure red cell aplasia due to anti-epoetin antibodies.

Case presentation

This report describes a 65-year-old Asian-American woman who developed pure red cell aplasia from high titer neutralizing anti-epoetin antibodies after epoetin-alfa therapy during ribavirin and peg-interferon treatment for chronic hepatitis C virus infection. We describe the outcome of her treatment with rituximab. The reticulocyte count increased, and anti-epoetin antibody titer decreased with a loss of neutralizing activity in vitro, leading to a reduction in blood transfusions, and eventual resolution of anemia, without reactivation of hepatitis C virus.

Conclusion

The diagnosis of pure red cell aplasia from anti-epoetin antibodies should be considered in patients undergoing therapy for chronic hepatitis C virus infection who develop severe anemia after administration of erythropoietin or darbepoetin. Though it is currently an off-label indication, rituximab is a therapeutic option for patients with pure red cell aplasia due to anti-epoetin antibodies.

Long-term safety and tolerability of epoetin zeta, administered intravenously, for maintenance treatment of renal anemia

INTRODUCTION

The aim of this trial was to gather data on the long-term safety of a new erythropoietin preparation (epoetin zeta), focusing on the formation of anti-erythropoietin antibodies, when administered intravenously for maintenance of target hemoglobin concentration in anemic patients with end-stage renal failure receiving chronic hemodialysis. In addition, we aimed to provide information on the efficacy of epoetin zeta under open, noncontrolled conditions.

METHODS

Patients received epoetin zeta intravenously, 1-3 times/week for 56 weeks (overall patient group, n=745) or 108 weeks (Bulgarian subgroup, n=164). The aim of treatment was to maintain hemoglobin values between 10.5 and 12.5 g/dL with constant epoetin dosage. Primary (safety) endpoints were the occurrence of anti-erythropoietin antibodies and the evaluation of adverse events (AEs). Secondary (efficacy) endpoints included the mean weekly dose of epoetin per kg of body weight and mean hemoglobin concentrations.

RESULTS

No patients developed neutralizing anti-erythropoietin antibodies. The most commonly reported AEs were infections and infestations (34.1%); followed by injury, poisoning, and procedural complications (25.8%); and gastrointestinal disorders (21.9%); 37.3% of patients reported serious AEs. The hemoglobin values remained stable, with mean values after 56 weeks of 11.3-11.6 g/dL for the overall group and 11.1-11.6 g/dL for the Bulgarian subgroup. The dosage of epoetin zeta was stable throughout the course of the trial. No cases of lack of (or loss of ) efficacy were observed in the course of the trial.

CONCLUSIONS

The evaluation of the primary endpoints provided data supporting the intravenous administration of epoetin zeta in patients with chronic renal failure. Neutralizing antibodies against erythropoietin were not detected, and there were no reports of patients with increasing erythropoietin resistance. Our results suggest that intravenous administration of epoetin zeta is effective regarding its ability to maintain stabilized hemoglobin levels within the target range of 10.5-12.5 g/dL.

Development of a chemiluminescent imaging assay for the detection of anti-erythropoietin antibody in human sera

Measuring low amounts of anti-erythropoietin antibodies (anti-EPO Abs) is important to evaluate the therapeutic safety of recombinant human erythropoietin (rhEPO). In this work, a simple, sensitive and high-throughput chemiluminescent (CL) imaging assay was developed for the detection of anti-EPO Abs in human sera. The influence of several physicochemical parameters, such as coating conditions, incubation time, detergent concentration and exposure time, were investigated. A calibration curve was established and the range of quantitative detection was 0.12-13.91 ng/mL. The limit of detection (LOD, 3sigma) for the CL-imaging assay was 0.033 ng/mL. Compared to conventional colorimetric enzyme-linked immunosorbent assay (ELISA), the LOD of the CL-imaging assay is 50-fold lower. The recoveries of anti-EPO Abs in the fortified serum were in the range 87.1-116.9% using the present method, which highlighted the validity of the CL-imaging assay system to accurately determine the anti-EPO Abs in serum samples. CL-imaging assay was used to evaluate the presence of anti-EPO Abs in serum samples obtained from chronic renal failure (CRF) patients treated with rhEPO. Contrary to what was expected, the sera from CRF patients did not contain anti-EPO Abs.

Case–control study of the association between select HLA genes and anti-erythropoietin antibody-positive pure red-cell aplasia

Aims: Antibody (Ab)-positive pure red-cell aplasia (PRCA) is a very rare but serious adverse event associated with recombinant human erythropoietin treatment (4.1 reports per 100,000 patient-years) in which patients produce antibodies to recombinant and endogenous erythropoietin, halting red blood cell production. In a previous case series, four Thai subjects with chronic kidney disease and Ab-positive PRCA were reported to have the HLA-DRB1*9 allele. To confirm a possible association of HLA-DRB1*9 and Ab-positive PRCA, we performed a pharmacogenomic analysis using subjects from an earlier case–control study of risk factors associated with Ab-positive PRCA, which had been performed using subjects from Europe or Canada. The primary goal of the analysis was to test the association between HLA-DRB1*9 and Ab-positive PRCA. A secondary goal was to perform an exploratory analysis in order to identify additional HLA alleles potentially associated with Ab-positive PRCA. Patients & Methods: Subjects were taken from a case–control study of Ab-positive PRCA in chronic kidney disease patients treated in Europe or Canada. Ab-positive PRCA cases (n = 24) were matched to controls (n = 81) by timing of treatment exposure and, when possible, by location. Results: The allele frequency of HLA-DRB1*9 was 12.5% in cases vs 1.2% in controls (p = 0.002). The frequency of the HLA-DRB1*9/other genotype was 25.0% in cases vs 2.5% in controls (p = 0.004; OR: 10.8 [95% CI: 2.2–53.7]). Within the exploratory analysis, six additional HLA alleles (HLA-A*25, HLA-B*53, HLA-C*12, HLA-DQB1*3, HLA-DQB1*6 and HLA-DRB1*4) were also found to be associated with Ab-positive PRCA. Conclusion: This study confirmed that HLA-DRB1*9 occurs at a significantly higher frequency in Ab-positive PRCA cases than in controls; however, within this sample set, carrying the *9 allele was neither necessary nor sufficient to cause Ab-positive PRCA.

Anti-erythropoietin antibody-mediated pure red cell aplasia in a living donor liver transplant recipient treated for hepatitis C virus

After liver transplantation, reinfection of the newly engrafted liver with hepatitis C virus is essentially universal in patients who are viremic at the time of transplantation. Treatment with interferon preparations with or without ribavirin is recommended in patients with marked histologic injury; however, hematologic toxicity associated with therapy has been reported, which is usually treated with growth factor support, including erythropoietin analogues. We present the first reported case of anti-erythropoietin antibody-mediated pure red cell aplasia arising in the setting of hepatitis C virus therapy in a patient who underwent living donor liver transplantation.

Thirty-nine cases of pure red cell aplasia: a single center experience from India

Pure red cell aplasia (PRCA) is an uncommon disorder, characterized by transfusion dependent anemia, reticulocytopenia with selective aplasia or paucity of erythroid cells in bone marrow. There are only a few large series of PRCA reported in literature. This is the largest single center series of PRCA from India.

OBJECTIVE

To evaluate the utility of Immunohistochemistry with Glycophorin A on bone marrow biopsies in quantitating the cut-off percentage of erythroid blasts required for diagnosis, as the upper cut-off percentage of erythroblasts for establishing a diagnosis of PRCA is still not clear.

METHODS

The clinical data were obtained from patients' case files. Immunohistochemistry with Glycophorin A was performed using an immunoperoxidase technique and percentage of Glycophorin A positive cells of all nucleated cells was calculated by two independent observers.

RESULTS

In our study, bone marrow aspirates showed a variable percentage of erythroblasts ranging from 2 to 12% (mean 6.3%) in children and from 1 to 8% (mean 4.6%) in adults on Giemsa smears. Immunohistochemistry (IHC) with Glycophorin A showed a mean positive cell % of 8.2 (range 2-16%) and 6.8 (1-9%) in pediatric and adult respectively against a mean of 28% (range 21-39%) in idiopathic thrombocytopenia (ITP) cases. Treatment with prednisone showed good response in a majority of both adults and childhood PRCA. Cyclosporine was found to be a good alternative in prednisone non-responders. Thymectomy was beneficial in patients with thymoma.

CONCLUSION

A higher percentage of erythroid cells (>5%) does not exclude a diagnosis of PRCA in an appropriate clinical setting and therefore can be managed as PRCA.

Biochemistry, physiology, and complications of blood doping: facts and speculation

Competition is a natural part of human nature. Techniques and substances employed to enhance athletic performance and to achieve unfair success in sport have a long history, and there has been little knowledge or acceptance of potential harmful effects. Among doping practices, blood doping has become an integral part of endurance sport disciplines over the past decade. The definition of blood doping includes methods or substances administered for non-medical reasons to healthy athletes for improving aerobic performance. It includes all means aimed at producing an increased or more efficient mechanism of oxygen transport and delivery to peripheral tissues and muscles. The aim of this review is to discuss the biochemistry, physiology, and complications of blood doping and to provide an update on current antidoping policies.

Detection of anti-EPO antibodies in human sera by a bridging ELISA is much more sensitive when coating biotinylated rhEPO to streptavidin rather than using direct coating of rhEPO

Sensitive and efficient methods for detecting anti-erythropoietin (anti-EPO) antibodies are needed for analysis and, above all, for large scale screening of human serum samples. ELISA is an attractive alternative to labor-intensive radioimmunoprecipitation assays but apparently conflicting reports question its sensitivity. We sought to resolve this issue by directly comparing different reported ELISA approaches to determine whether rhEPO-coating methods affect detection of anti-EPO antibodies. Investigators reporting low sensitivity had used ELISAs in which rhEPO was directly coated to microtiter plates while the high sensitivity ELISA used plate-bound streptavidin to bind biotinylated rhEPO. Using anti-EPO positive human sera, our results confirmed a large (100- to 300-fold) difference in sensitivity between the ELISAs and suggested that the inferiority of the low sensitivity ELISA was caused by the direct coating of rhEPO which may disrupt epitopes by masking recognition sites or introducing conformational changes. Thus, a bridging ELISA can be an appropriate and effective system for antibody analysis and screening of human sera with high sensitivity and specificity but only if performed with streptavidin binding of biotinylated antigen. This finding may also be more generally applicable to the detection of antibodies against other protein antigens.

A cluster of parvovirus B19 infections in renal transplant recipients: a prospective case series and review of the literature

Up to 9% of renal transplant recipients have severe multifactorial erythropoietin-resistant anemia. Human parvovirus B19 (PVB19) infection can cause severe anemia and is likely underreported. Sparse information on epidemiology and management in this population exists. To address these issues, after our first index case, we modified our clinical practice to prospectively screen patients with persistent hemoglobin (Hb) <10 mg/dL for PVB19 infection after excluding common causes of anemia including erythropoietin resistance. Potentially infected patients were further evaluated by serology, qualitative polymerase chain reaction (quPCR) and bone marrow biopsy (BMB) for cytomegalovirus, Epstein-Barr virus, PVB19 and other etiologies. Over 3 months, 212 kidney recipients visited outpatient clinics. Of 52 recipients with anemia, 8 had an Hb <10 mg/dL with erythropoietin resistance and were screened for PVB19 infection. Three cases had PVB19 infection by quPCR and often-inconclusive serology/BMB results. Cases had immunosuppression reduced and received IVIG (0.5 gm/kg x 4 doses) with recovery from anemia, viral clearance in two cases and one recurrence. PVB19-mediated anemia occurred in up to three out of eight (38%) screened kidney recipients with Hb <10 mg/dL resistant to erythrypoietin. We recommend prospective risk stratification for this population, high indices of suspicion using at least qualitative techniques for diagnosis and treatment goal for viral eradication.

Long-term outcome of individuals with pure red cell aplasia and antierythropoietin antibodies in patients treated with recombinant epoetin: a follow-up report from the Research on Adverse Drug Events and Reports (RADAR) Project

Since its introduction in 1988, recombinant human erythropoietin (epoetin) has been standard treatment for patients with anemia due to chronic kidney disease. From 1998 to 2004, nearly 200 epoetin-treated persons with chronic kidney disease developed antibodies to epoetin, resulting in pure red cell aplasia (PRCA). The majority of these patients received Eprex, an epoetin alfa product marketed exclusively outside the United States. Herein, we report on the long-term outcome of these individuals. For 170 chronic kidney disease patients who developed epoetin-associated PRCA and had 3 months or more follow-up information available, case reports from the Food and Drug Administration and epoetin manufacturers were reviewed for information on clinical characteristics of the patients, immunosuppressive treatments, epoetin responsiveness, and hematologic recovery. Overall, 64% of the PRCA patients received immunosuppressive therapy, including 19 who also underwent a renal transplantation. Thirty-seven percent experienced a hematologic recovery, with higher hematologic recovery rates among PRCA patients who received immunosuppressive therapy (57% vs 2%, P < .001). Among 34 patients who received epoetin after the onset of PRCA, 56% regained epoetin responsiveness. The highest rates of epoetin responsiveness were observed among persons whose antierythropoietin antibodies were undetectable when epoetin was administered (89%). Among chronic kidney disease patients with epoetin-associated PRCA, epoetin discontinuation and immunosuppressive therapy or renal transplantation is necessary for hematologic recovery. Reinitiation of epoetin therapy among individuals could be considered if antierythropoietin antibodies are undetectable.