Antibody-mediated pure red cell aplasia related with epoetin-beta pegol (C.E.R.A.) as an erythropoietic agent: case report of a dialysis patient.

BACKGROUND: Erythropoietin-stimulating agents (ESAs) are used to treat anemia in patients with chronic kidney disease, enabling maintenance of stable hemoglobin levels and eliminating the need for multiple transfusions. Epoetin-beta pegol (C.E.R.A.) is a continuous erythropoietin receptor activator created by integrating a large methoxy-polyethylene-glycol-polymer chain into the erythropoietin molecule, which provides it with a longer half-life. On rare occasions, cases of antibody-mediated pure red cell aplasia (PRCA) related to ESAs are reported. They are characterized by abrupt onset of severe transfusion-dependent anemia, despite ESA therapy. We herein report a case of antibody-mediated PRCA in a dialysis patient receiving C.E.R.A. CASE PRESENTATION: A 44-year-old man with end-stage renal failure had been receiving continuous ambulatory peritoneal dialysis for 2 years. C.E.R.A. was administered subcutaneously as a sole ESA once a month at the hospital since 4 years ago for the treatment of renal anemia and his hemoglobin level was well controlled at 12 g/dl. From 10 months before diagnosis, however, his hemoglobin level suddenly declined, necessitating frequent transfusions. Based on the results of a bone marrow examination and detection of anti-C.E.R.A. antibodies, the patient was diagnosed with antibody-mediated PRCA. After successful elimination of the antibodies using oral prednisolone plus cyclosporine, the patient was re-administrated C.E.R.A. intravenously, as there are few reports of antibody-mediated PRCA related to ESA using that administration route. He responded to the C.E.R.A., and his anemia dramatically improved, eliminating the need for blood transfusions. CONCLUSIONS: This is the first reported case of recovery from an antibody-mediated PRCA with C.E.R.A. after its re-administration following a reversal of the antibody. It has been suggested that the additional large pegylation chain makes C.E.R.A. less likely to trigger antibody generation than other ESAs. Following successful treatment of antibody-mediated PRCA using immunosuppressive therapy, C.E.R.A. can be re-administered intravenously to treat renal anemia.

Will there still be a role for the originator erythropoiesis-simulating agents after the biosimilars and the hypoxia-inducible factor stabilizers approval?

PURPOSE OF REVIEW: To discuss if there will still be a role for the originator ESAs after the already available biosimilars and the approval of HIF stabilizers in the near future. RECENT FINDINGS: Current treatment with erythropoiesis-simulating agents (ESAs) is effective and generally well tolerated, but requires parenteral injections. It is also surrounded by safety concerns and is still expensive. Functional iron deficiency is the major obstacle for efficient ESA therapy. ESA resistance may develop, calling for high ESA doses, further increasing the side effects associated with ESA use. Biosimilars were introduced for reducing costs. In searching for an ideal antianemic drug, new investigational strategies have been proposed including the attractive alternative hypoxia-inducible factor (HIF) stabilizers, which stimulate endogenous EPO production. However, we should caution in translating the historical results referring to the side effects of ESAs to current clinical practice, considering that hemoglobin targets and ESAs doses are now much lower. We could anticipate that side effects will be much less. SUMMARY: According to preliminary data, orally administered HIF stabilizers could provide pharmacological advantages over the existing ESAs. These will need confirmation by the findings of large, phase-3, clinical trials. Finally, cost will be an important issue determining their future use.

Biosimilar erythropoiesis-stimulating agents and the risk of developing anti-drug antibodies-a systematic review.

PURPOSE: We systematically reviewed published observational studies and randomized controlled trials (RCT) reports of clinical trials on erythropoiesis-stimulating agents (ESA's). Only studies evaluating the risk of developing anti-drug antibodies (ADA) of both original and biosimilar drugs were chosen. METHODS: Databases including PubMed, EMBASE and Cochrane Library were searched up to 17 March 2015. Two reviewers independently assessed the relevant studies for risk of bias. RESULTS: Twenty-one publications were included. The overall prevalence of ADA in the studies was about 0.2 to 0.5 %. Most studies were not designed to monitor the development of ADA and often the study duration was too short (less than 6 months) and the patient population too small. Moreover, in many studies, the assays used only determined the presence of ADA and did not measure therapy failure due to ADA. In one RCT, as many as 13 cases (4 %) of ADA were identified. CONCLUSION: ADA development seems to be low in short-term studies with ESA. None of the efficacy and safety issues for ESA biosimilars were judged to be adequately addressed in the evaluated literature, with respect to ADA formation, due to the study design and the assay method used.

Chronic preclinical safety evaluation of EPO-018B, a pegylated peptidic erythropoiesis-stimulating agent in monkeys and rats.

EPO-018B, a synthetic peptide-based erythropoiesis stimulating agent (ESA), is mainly designed for treatment of anemia caused by chronic renal failure and chemotherapy against cancer. It overcomes the deficiencies of currently approved ESA, including the frequent administration of temperature-sensitive recombinant protein and anti-EPO antibody-mediated pure red cell aplasia (PRCA). This study was designed to evaluate the potential chronic toxicity of EPO-018B. Subcutaneous administration doses were designed as 0, 0.2, 1 and 10mg/kg for six months for 160 rats (20/gender/group) and 0, 0.3, 3 and 20mg/kg for nine months for 32 monkeys (4/gender/group) once every three weeks. The vehicles received the same volume of physiological saline injection. All animals survived to the scheduled necropsies after six weeks (for rats) and fourteen weeks (for monkeys) recovery period, except for the two high-dose female rats and two high-dose male monkeys, which were considered related to the increased RBCs, chronic blood hyperviscosity and chronic cardiac injury. EPO-018B is supposed to be subcutaneously injected once every month and the intended human therapeutic dose is 0.025mg/kg. The study findings at 0.2mg/kg for rats and 0.3mg/kg for monkeys were considered to be the study NOAEL (the no observed adverse effect level), which were more than ten times the intended human therapeutic dose. Higher doses caused adverse effects related to the liver toxicity, cardiotoxicity, appearance of neutralizing antibodies of EPO-018B and the decrease of serum glucose and cholesterol. Most treatment-induced effects were reversible or revealed ongoing recovery upon the discontinuation of treatment. The sequelae occurred in rats and monkeys were considered secondary to exaggerated pharmacology and would less likely occur in the intended patient population. As to the differences between human beings and animals, the safety of EPO-018B need to be further confirmed in the future clinical studies.

[Anaphylaxis after iron dextran administration in a pregnant woman]. / Anafylaxie na ijzerdextraan bij een zwangere vrouw.

BACKGROUND: Iron deficiency is a frequent cause of anaemia in pregnancy and often results in fatigue and malaise. To prevent complications during labour, timely iron suppletion is important. CASE DESCRIPTION: A 30-year-old multiparous female presented at the outpatient clinic in her 38th week of this pregnancy because of fatigue and lightheadedness. She had been prescribed oral iron suppletion a month earlier but had not taken the tablets. Because her haemoglobin level had decreased to 6.3 mmol/l, it was decided to start her on intravenous iron dextran treatment. During administration of the test dose, the patient experienced acute dyspnoea and severe abdominal and back pain. Foetal bradycardia was observed and the patient underwent an emergency caesarean section. She delivered a healthy boy whose arterial pH was 7.05 (base excess: -7.6 mmol/l) and venous pH was 7.18 (base excess: -6.8 mmol/l). CONCLUSION: This case demonstrates that dextran anaphylaxis can occur, with potentially lethal consequences, even when no known underlying risk factors are present.

A detailed examination of the antibody prevalence and characteristics of anti-ESA antibodies.

BACKGROUND: The antibody characteristics in erythropoiesis-stimulating agent (ESA)-treated patients who develop antibody-mediated pure red cell aplasia (PRCA; amPRCA) can be described as high-affinity, neutralizing anti-ESA antibodies with a mixed immunoglobulin G (IgG) subclass. The characteristics of an early-onset anti-ESA antibody response are not well documented, especially in the months prior to the development of amPRCA. Therefore, a detailed characterization of anti-ESA antibodies was performed in patients in both clinical studies and in a post-market setting. Both baseline and post-dose samples were tested and antibody-positive samples were characterized. Antibody characteristics such as concentration, isotype and specificity were evaluated in subjects with non-neutralizing anti-ESA antibodies and subjects that developed neutralizing anti-ESA antibodies associated with amPRCA. METHODS: Serum samples were analyzed for the presence of anti-ESA antibodies, using a validated surface plasmon resonance (SPR)-based immunoassay or SPRIA. RESULTS: Among the clinical studies, pre-existing non-neutralizing anti-ESA antibodies were found in 6% of the subjects from clinical studies in nephrology, oncology and congestive heart failure (CHF). After ESA treatment, 2.3% of the subjects developed binding, non-neutralizing antibodies with 0.1% confirmed as having an IgG isotype and were specific to the ESA protein. IgM antibodies were detected at baseline and post-ESA treatment and reported to be specific to the glycosylation of the ESA. No clinical study subjects progressed to amPRCA. In contrast, anti-ESA antibody-positive subjects from the post-market setting with a confirmed IgG subclass were specific to the ESA protein. Subjects that had progressed to amPRCA were noted to have high antibody concentrations with neutralizing activity and a diverse IgG subtype. CONCLUSIONS: A low prevalence of non-neutralizing anti-ESA IgM specific to glycosylation on the ESA and IgG1 antibodies specific to the ESA protein was detected across all clinical patient populations. Patients with amPRCA were noted to have high IgG antibody concentrations, neutralizing antibodies and the presence of anti-ESA IgG4 antibodies.

Prospective multicenter study of HX575 (biosimilar epoetin-α) in patients with chronic kidney disease applying a target hemoglobin of 10--12 g/dl.

HX575 was approved in the European Union in August 2007 as the first-ever biosimilar epoetin-α product. The present study extended the safety database on HX575 by monitoring adverse events (AEs) in clinical practice. Hemoglobin (Hb) levels and HX575 doses were recorded for the assessment of efficacy. This open, 6-month single-arm study was conducted in 10 European countries with a target enrollment of 1,500 patients with anemia due to chronic kidney disease (CKD). HX575 was intravenously (i.v.) administered aiming at an Hb target of 10 - 12 g/dl. Most patients (92.3%) had already received erythropoiesis stimulating agents (ESAs) treatment before enrolment into this study; the recorded treatments mainly comprised i.v. or subcutaneous (s.c.) administration of epoetin-α, epoetin-ß or darbepoetin. The study period covered 770 patient years. The observed AE profile was in line with expectations for this patient population. Thrombotic vascular events (TVEs) were reported in 11.9% of patients (0.2612 per patient year). Tumor incidence was 1.4% (0.0299 per patient year). No subject developed anti-epoetin antibodies. Mean Hb levels were effectively maintained between 11.2 and 11.3 g/dl following the conversion from a broad spectrum of pre-study ESA treatments with stable overall mean i.v. HX575 doses. The proportion of patients within the Hb target range increased from 57.5% at baseline to 66.8% at study end.

Development and characterization of a human antibody reference panel against erythropoietin suitable for the standardization of ESA immunogenicity testing.

Recombinant human erythropoietin (EPO) has been used therapeutically for more than two decades in the treatment of anemia. Although EPO is generally well tolerated, in rare cases, patients have developed anti-EPO antibodies that can negatively impact safety and efficacy. Therefore, the detection of antibodies against EPO is a regulatory requirement during clinical development and post-approval. Although it is a rare phenomenon, antibody-mediated pure red cell aplasia (PRCA) is a serious complication than can result from antibodies that develop and neutralize EPO as well as endogenous erythropoietin. Currently, there are no universally accepted analytical methods to detect the full repertoire of binding and neutralizing anti-EPO antibodies. A number of different methods that differ in terms of antibodies detected and assay sensitivities are used by different manufacturers. There is also a lack of antibody reference reagents, and therefore no consistent basis for detecting and measuring anti-EPO antibodies. Reference reagents, with established ranges, are essential to monitor the safety and efficacy of all erythropoiesis-stimulating agents (ESAs) structurally related to human erythropoietin. This is the first report of the development and characterization of a panel of fully human antibodies against EPO suitable as reference reagents. The characteristics of antibodies within the panel were selected based on the prevalence of non-neutralizing IgG and IgM antibodies in non-PRCA patients and neutralizing IgG antibodies, including IgG1 and IgG4, in antibody-mediated PRCA subjects. The reference panel includes antibodies of high- and low-affinity with binding specificity to neutralizing and non-neutralizing erythropoietin epitopes. The subclass of human antibodies in this reference panel includes an IgG1, IgG2, and IgG4, as well as an IgM isotype. This antibody panel could help select appropriate immunogenicity assays, guide validation, and monitor assay performance. Further, this human anti-ESA antibody panel may help set the limits of each assay platform in terms of the full repertoire of the anti-ESA antibodies, and may facilitate standardization of ESA immunogenicity reporting across assay platforms.

Antibody-mediated pure red cell aplasia in chronic kidney disease patients receiving erythropoiesis-stimulating agents: new insights.

Antibody-mediated pure red cell aplasia is a very rare but devastating condition affecting patients receiving treatment with erythropoiesis-stimulating agents. New cases continue to emerge, generally in clusters, consistent with an 'environmental' trigger to its pathogenesis. Defining the causes of antibody-mediated pure red cell aplasia is clearly of importance for patients with chronic kidney disease, but any developments in this area may also have relevance to other disease areas as therapeutic delivery of endogenous proteins rapidly increases. This review focuses on the current knowledge regarding the etiology of antibody-mediated pure red cell aplasia and the current approach to therapy.

Detection of anti-ESA antibodies in human samples from PRCA and non-PRCA patients: an immunoassay platform comparison.

BACKGROUND: The immunological methods for detecting antibodies to erythropoiesis-stimulating agents (ESAs) differ in assay sensitivity. However, this parameter, routinely determined in clinical assays using a high-affinity non-human polyclonal antibody, gives a one-dimensional assessment of antibody detection. We compare three widely used immunological methods and evaluate the ability of each to detect mature human antibodies and human antibodies characteristic of an early immune response. METHODS: The detection of anti-ESA antibodies was compared between a radioimmunoprecipitation (RIP) assay, an electrochemiluminescence (ECL) bridging enzyme-linked immunosorbent assay and a surface plasmon resonance (SPR)-based immunoassay. All three methods were validated for sensitivity, specificity and precision. Specimens from clinical studies or post market testing were categorized as pure red cell aplasia (PRCA) or non-PRCA and then analyzed in each method. RESULTS: Among the antibody-mediated PRCA samples, which contain high affinity neutralizing antibodies, there was strong correlation between all methods. The results from non-PRCA sample analysis show high correlation between RIP and ECL methods; however, differences between the SPR immunoassay and the ECL and RIP were demonstrated. The samples that scored positive in the SPR immunoassay and negative by RIP and ECL were characterized to be of low antibody concentration, contained a high percentage of rapidly dissociating antibodies, or were antibodies of the IgM isotype. CONCLUSIONS: All three immunological methods are appropriate for detection of antibodies associated with antibody-mediated PRCA. However, the SPR immunoassay platform detected an early, low affinity IgG and IgM antibody response as well as detected and characterized a pathogenic antibody response associated with antibody-mediated PRCA.

Tungsten-induced denaturation and aggregation of epoetin alfa during primary packaging as a cause of immunogenicity.

PURPOSE: Following two cases of neutralizing antibodies to epoetin alfa in an investigational clinical study, a small number of individual syringes of two drug product batches were found to contain unusually high levels of aggregation at the end of the clinical trial. METHODS: We undertook an extensive analytical approach to determine the root-cause of the increased aggregation in the affected batches. RESULTS: Soluble tungsten was found in the syringes, most likely derived from the pins used to manufacture the syringes. Spiking of epoetin alfa with sodium polytungstate or an extract of tungsten pins used to manufacture the syringes induced the formation of aggregates, both dimers that appeared to be covalently linked by disulphide bonds as well as higher-order aggregates. Sodium polytungstate had also a strong denaturing effect on the protein. CONCLUSIONS: We propose tungsten-mediated unfolding and aggregation of epoetin alfa in pre-filled syringes as a potential root cause for increased immunogenicity. This finding may be more broadly applicable to this and other classes of therapeutic proteins.

Safety, immunogenicity and efficacy of subcutaneous biosimilar epoetin-α (HX575) in non-dialysis patients with renal anemia: a multi-center, randomized, double-blind study.

BACKGROUND: HX575 is a biosimilar version of epoetin-α that is approved for the treatment of anemia associated with chronic kidney disease (CKD) using the intravenous route of administration. Here we report data from a study of anemic pre-dialysis patients to assess the safety, immunogenicity and efficacy of subcutaneous (s.c.) administration of HX575 vs. Erypo®/Eprex® (Ortho Biotech, Neuss, Germany). METHODS: This was a randomized, double-blind study in adult patients (n = 337) with Stage III - V CKD and a hemoglobin (Hb) level of 7.5 - 11.0 g/dl. Eligible patients were randomized to 52 weeks of treatment with HX575 or Erypo®/Eprex® at a starting dose of 25 IU/kg body weight 3 times weekly or 75 IU/kg body weight once weekly during Weeks 1 - 5. This could be adjusted after 5 weeks to maintain Hb levels between 10 and 12 g/dl. The primary objective was to assess the safety and immunogenicity of HX575 compared with Erypo®/Eprex®. Efficacy endpoints were mean absolute change in Hb from baseline to end of Week 13 and mean weekly epoetin dosage in Weeks 11 - 13. RESULTS: HX575 was equivalent to Erypo®/Eprex® in terms of maintaining Hb levels and epoetin dose requirements. Two patients in the HX575 group developed neutralizing antibodies (NAbs) to erythropoietin, which resulted in the study being terminated prematurely. Aside from these two events, reported adverse events were as expected for patients with Stage III - V CKD and similar in both treatment groups. CONCLUSIONS: This study demonstrated the efficacy and therapeutic equivalence of s.c. HX575 compared with the reference epoetin-α, but 2 patients developed NAbs during treatment with s.c. HX575 in this study. Results of a thorough root-cause analysis reported elsewhere indicate that increased tungsten exposure in pre-filled syringes precipitated immunogenic reactions.

Improvement in erythropoieis-stimulating agent-induced pure red-cell aplasia by introduction of darbepoetin-α when the anti-erythropoietin antibody titer declines spontaneously.

Anti-erythropoietin antibodies usually cross-react with all kinds of recombinant erythropoietins; therefore, erythropoiesis-stimulating agent (ESA)-induced pure red-cell aplasia (PRCA) is not rescued by different ESAs. Here, we present a case of ESA-induced PRCA in a 36-yr-old woman with chronic kidney disease, whose anemic condition improved following reintroduction of darbepoetin-α. The patient developed progressive, severe anemia after the use of erythropoietin-α. As the anemia did not improve after the administration of either other erythropoietin-α products or erythropoietin-ß, all ESAs were discontinued. Oxymetholone therapy failed to improve the transfusion-dependent anemia and a rechallenge with ESAs continuously failed to obtain a sustained response. However, her anemia improved following reintroduction of darbepoetin-α at 3 yr after the initial diagnosis. Interestingly, anti-erythropoietin antibodies were still detectable, although their concentration was too low for titration. In conclusion, darbepoetin-α can improve ESA-induced PRCA when the anti-erythropoietin antibody titer declines and its neutralizing capacity is lost.

Antiepoetin antibody-related pure red cell aplasia: successful remission with cessation of recombinant erythropoietin alone.

An elderly patient with pure red cell aplasia (PRCA) with antierythropoietin (anti-EPO) antibodies is described. PRCA due to alloimmunization is a rare and severe complication of recombinant human erythropoietin (rHu-EPO) therapy. Most reported patients with PRCA were cured primarily by immunosuppressive drug therapy. The patient in this case, however, did not want to receive any immunosuppressive drugs. Therefore, rHu-EPO injection was simply discontinued, the severe anemia gradually improved, and the hemoglobin approached normal range. This case is very rare and significant in that there have been few such elderly patients with rHu-EPO-induced PRCA in whom PRCA remission was achieved, with decreasing antibody titers, after cessation of rHu-EPO alone. Further cases are needed to assess how PRCA should be treated in patients with anti-EPO antibodies.

Anti-erythropoietin antibodies followed by endogenous erythropoietin production in a dialysis patient.

We present a case of a young girl with end-stage renal disease secondary to anti-glomerular basement membrane disease who was receiving maintenance peritoneal dialysis and developed pure red cell aplasia secondary to anti-erythropoietin (EPO) antibodies. This occurred 13 months after the initiation of EPO alfa therapy for anemia. Initially, the patient required intermittent red blood cell transfusions. After immunosuppressive therapy had been initiated with corticosteroids and cyclosporine, the EPO antibody levels decreased precipitously, associated with an increased level of endogenous EPO production. For the following 6 months, the patient maintained adequate (>10 g/dL) hemoglobin levels and did not require red cell transfusions.