Switching epoetin alfa and epoetin zeta in patients with renal anemia on dialysis: Posthoc analysis

Safety of Biologics, Including Biosimilars: Perspectives on Current Status and Future Direction

In recent years, marketing of highly innovative and costly biologics improved the management of high-burden diseases such as autoimmune diseases, cancers, and chronic renal failure. Several widely prescribed biologics have recently lost or will shortly lose their patents, thus opening avenues to the marketing of a growing number of biosimilars worldwide, which are products similar in terms of quality, safety, and efficacy to already licensed reference products, thus allowing for potential savings in pharmaceutical expenditure. Numerous debates about the interchangeability between biosimilars and reference products are still ongoing, owing to concerns about potential immunogenicity raised by switching, which may cause a lack of effect and toxicity. Patients successfully treated with biologic therapy may theoretically receive biosimilars to contain costs, if reference product and related biosimilar are judged as interchangeable. However, the positions of regulatory agencies on the interchangeability and automatic substitution of biologics with biosimilars are very different. The benefit-risk profile of biosimilars has been often questioned by clinicians owing to the limited amount of pre-marketing information on clinical efficacy and safety, despite biosimilarity being based on a comparability exercise with the reference product to gain the biosimilar approval. Nevertheless, after more than 10 years of marketing from the first biosimilar approval in Europe, no proof of differences in terms of the safety profile of biosimilars and originators has been reported. In this context, post-marketing evaluation of both biologics and biosimilars safety profiles through analyses from spontaneous reporting databases and claims databases is crucial. An important issue for the pharmacovigilance of biologics concerns the traceability, indicating the brand name and batch number in spontaneous adverse drug reaction reports, but this requirement is not frequently addressed. This review aims to provide an overview of the characteristics and potential challenges in the safety profile assessment of biologics with a focus on the post-marketing setting.

Switching from an originator anti-TNF to a biosimilar in patients with inflammatory bowel disease: Can it be recommended? A systematic review

AIM

To review the effectiveness and safety of switching from an originator anti-TNF (Remicade^®) to a biosimilar (CT-P13) in patients with inflammatory bowel disease (IBD).

METHODS

Electronic and manual search up to September 2017.

RESULTS

We identified 24 studies evaluating switching between Remicade^® and CT-P13 in 1326 patients. Disease control (no worsening after switching) was confirmed in most of the patients (weighted mean, 88%; 95% CI=86-89%). No unexpected adverse effects were reported in any of the studies.

CONCLUSION

The risks of switching from Remicade^® to a biosimilar seem to be purely theoretical and are not supported by the (still limited) real-world clinical practice experience. On the contrary, a steadily increasing number of publications have shown that there seem to be no safety or efficacy concerns about switching. Therefore, switching from originator to biosimilar infliximab in patients with IBD may be considered acceptable.

Comparative risk/benefit profile of biosimilar and originator erythropoiesis-stimulating agents (ESAs): data from an Italian observational study in nephrology

PURPOSE

The aim of this multicenter prospective study was to evaluate efficacy and safety of biosimilar erythropoiesis-stimulating agents (ESAs) vs originator, based on data from clinical practice in patients with chronic kidney disease (CKD).

METHODS

We collected data of the patients with diagnosis of CKD on conservative treatment from nine Italian structures. Patients were enrolled applying different exclusion criteria, and various individual parameters were registered at the beginning for descriptive analysis. Patients were treated with epoetin alfa, beta, and darbepoetin as originator and epoetin zeta as biosimilar. Hemoglobin levels have been analyzed at baseline and after 3, 6, and 12 months. Descriptive statistics were used to analyze the results.

RESULTS

At baseline, 47 patients were in the biosimilar group and 57 in the originator; the basal level of hemoglobin was similar between the groups (mean Hb 9.4 and 9.3 g/dL, respectively). Median age, weight, and comorbidities were almost comparable. After 3 months, 44 patients remained in the biosimilar group and 48 in the originator; hemoglobin increase was significantly greater in patients treated with biosimilar [absolute increase 1.6 vs 1.0 g/dL, p < 0.001]. After 6 and 12 months, number of patients fall furthermore. Hemoglobin levels increased more in the biosimilar group after 6 months (2.1 vs 1.1 g/dL, p < 0.001) and 12 months (2.0 vs 1.0 g/dL, p < 0.001).

CONCLUSIONS

Biosimilar ESAs have similar risk/benefit profile compared to originators. Our data are in agreement with relevant scientific literature and, on the other hand, they are in contrast with common thought that considers biosimilar less efficacious and less safe than originators.

Biosimilarity and Interchangeability: Principles and Evidence: A Systematic Review

BACKGROUND

The efficacy, safety and immunogenicity risk of switching between an originator biologic and a biosimilar or from one biosimilar to another are of potential concern.

OBJECTIVES

The aim was to conduct a systematic literature review of the outcomes of switching between biologics and their biosimilars and identify any evidence gaps.

METHODS

A systematic literature search was conducted in PubMed, EMBASE and Cochrane Library from inception to June 2017. Relevant societal meetings were also checked. Peer-reviewed studies reporting efficacy and/or safety data on switching between originator and biosimilar products or from one biosimilar to another were selected. Studies with fewer than 20 switched patients were excluded. Data were extracted on interventions, study population, reason for treatment switching, efficacy outcomes, safety and anti-drug antibodies.

RESULTS

The systematic literature search identified 63 primary publications covering 57 switching studies. The reason for switching was reported as non-medical in 50 studies (23 clinical, 27 observational). Seven studies (all observational) did not report whether the reasons for switching were medical or non-medical. In 38 of the 57 studies, fewer than 100 patients were switched. Follow-up after switching went beyond 1 year in eight of the 57 studies. Of the 57 studies, 33 included statistical analysis of disease activity or patient outcomes; the majority of these studies found no statistically significant differences between groups for main efficacy parameters (based on P < 0.05 or predefined acceptance ranges), although some studies observed changes for some parameters. Most studies reported similar safety profiles between groups.

CONCLUSIONS

There are important evidence gaps around the safety of switching between biologics and their biosimilars. Sufficiently powered and appropriately statistically analysed clinical trials and pharmacovigilance studies, with long-term follow-ups and multiple switches, are needed to support decision-making around biosimilar switching.

Is there a reason for concern or is it just hype? - A systematic literature review of the clinical consequences of switching from originator biologics to biosimilars

INTRODUCTION

While prescribing biosimilars to patients naive to a biologic treatment is a well-accepted practice, switching clinically stable patients from an originator to a biosimilar is an issue for clinicians. Well-designed clinical trials and real-world data which study the consequences of switching from an originator biologic treatment to its biosimilar alternative are limited, especially for monoclonal antibodies. Areas covered: A systematic literature review was conducted on PubMed to identify evidence of the consequences of switching from original biologics to biosimilars. References of included papers were also scrutinized. After a title-, abstract- and full text screening, out of the 153 original hits and 77 additional ones from screening the references, 58 papers (12 empirical papers, 5 systematic reviews and 41 non-empirical papers) were included. Expert opinion: Preventing patients on biologic medicines from switching to biosimilars due to anticipated risks seems to be disproportional compared to the expected cost savings and/or improved patient access. Indeed, it is the opinion of the authors that the concern of switching to biosimilars is overhyped.

Switching Between Epoetins: A Practice in Support of Biosimilar Use

Background

The acceptability of switching between reference drugs and their biosimilars is often disputed. It is unclear whether this concern is specific to the use of biosimilars or is relevant to the practice of switching between any biological drugs.

Objective

The objective of this study was to quantify the occurrence of switching between different erythropoiesis-stimulating agents.

Methods

A retrospective drug utilization study was conducted in the Umbria region (Italy). The study population included all residents who received their first epoetin prescription between 1 July 2011 and 31 December 2014. The Umbria drug prescription database and the regional archive of residents were used to gather information. Switching was defined as any transition between different epoetins (different substances and/or different products of the same substance) in a series of two prescriptions. The probability of switching was described in relationship to the duration of treatment in a survival analysis.

Results

Overall, 3258 subjects received prescriptions of epoetins. Among the 2896 patients with at least two prescriptions, 354 (12.2 %) experienced one or more switches. The probability of switching depended on the duration of treatment: approximately 15 % of users switched within 12 months of observation and 25 % switched within 2 years. Switching was not limited to reference and biosimilar epoetins and it affected patent and off-patent epoetins equally.

Conclusions

Switching between different epoetins was related to the duration of use and most episodes of switching involved epoetins that have never been contrasted in a comparability exercise. The present level of switching may provide reassurance to physicians when taken together with other sources of comparative evidence.

Electronic supplementary material

The online version of this article (doi:10.1007/s40259-015-0155-0) contains supplementary material, which is available to authorized users.

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.

How Much Are Biosimilars Used in Clinical Practice? A Retrospective Italian Population-Based Study of Erythropoiesis-Stimulating Agents in the Years 2009-2013

Purpose

To explore the prescription patterns of erythropoiesis-stimulating agents (ESAs) in four large Italian geographic areas, where different health policy interventions to promote biosimilar use in routine care are undertaken.

Methods

A retrospective drug utilization study was conducted during the years 2009–2013. The data sources were the administrative databases of the Tuscany region and of the Caserta, Palermo, and Treviso Local Health Units (LHUs). The characteristics, prevalence, and switching patterns of different ESAs (biosimilars and reference products), stratified by indication for use, were calculated over time and across centers.

Results

Overall, 49,491 patients were treated with ESAs during the years 2009–2013 in the four centers. Of these, 41,286 patients (83.4 %) were naive users. The prevalence of ESA use increased from 2.9 to 3.4 per 1000 inhabitants in the years 2009–2011 but decreased thereafter (3.0 per 1000 in 2013). Moreover, the proportion of biosimilar users increased overall from 1.8 % in 2010 to 33.6 % in 2013, with larger increase in Treviso (from 0.0 to 45.0 %) and Tuscany (from 0.7 to 37.6 %) than in Caserta (from 7.5 to 22.9 %) and Palermo (from 0.0 to 27.7 %). Switching between different ESAs during the first year of therapy was frequent (17.0 %), much more toward reference products than toward biosimilars.

Conclusion

Overall, the prevalence of ESA use decreased slightly, while use of biosimilar ESAs, especially in naive patients, increased significantly but to different extents in these four large Italian geographic areas. Switching between different ESAs during the first year of treatment was very frequent, which may affect pharmacovigilance monitoring. New strategies are necessary to further improve market penetration of low-cost medicines, such as biosimilars, and also to harmonize effective health policy interventions that aim to reduce pharmaceutical expenses and optimize patient benefit across all regions.

Electronic supplementary material

The online version of this article (doi:10.1007/s40259-015-0132-7) contains supplementary material, which is available to authorized users.

Efficacy and safety of CT-P13 (biosimilar infliximab) in patients with rheumatoid arthritis: comparison between switching from reference infliximab to CT-P13 and continuing CT-P13 in the PLANETRA extension study

OBJECTIVES

To assess the efficacy and safety of switching from the infliximab reference product (RP; Remicade) to its biosimilar CT-P13 (Remsima, Inflectra) or continuing CT-P13 in patients with rheumatoid arthritis (RA) for an additional six infusions.

METHODS

This open-label extension study recruited patients with RA who had completed the 54-week, randomised, parallel-group study comparing CT-P13 with RP (PLANETRA; NCT01217086). CT-P13 (3 mg/kg) was administered intravenously every 8 weeks from weeks 62 to 102. All patients received concomitant methotrexate. Endpoints included American College of Rheumatology 20% (ACR20) response, ACR50, ACR70, immunogenicity and safety. Data were analysed for patients who received CT-P13 for 102 weeks (maintenance group) and for those who received RP for 54 weeks and then switched to CT-P13 (switch group).

RESULTS

Overall, 302 of 455 patients who completed the PLANETRA study enrolled into the extension. Of these, 158 had received CT-P13 (maintenance group) and 144 RP (switch group). Response rates at week 102 for maintenance versus switch groups, respectively, were 71.7% vs 71.8% for ACR20, 48.0% vs 51.4% for ACR50 and 24.3% vs 26.1% for ACR70. The proportion of patients with antidrug antibodies was comparable between groups (week 102: 40.3% vs 44.8%, respectively). Treatment-emergent adverse events occurred in similar proportions of patients in the two groups during the extension study (53.5% and 53.8%, respectively).

CONCLUSIONS

Comparable efficacy and tolerability were observed in patients who switched from RP to its biosimilar CT-P13 for an additional year and in those who had long-term CT-P13 treatment for 2 years.

TRIAL REGISTRATION NUMBER

NCT01571219; Results.

Efficacy and safety of switching from reference infliximab to CT-P13 compared with maintenance of CT-P13 in ankylosing spondylitis: 102-week data from the PLANETAS extension study

OBJECTIVES

To investigate the efficacy and safety of switching from infliximab reference product (RP) to its biosimilar or maintaining biosimilar treatment in patients with ankylosing spondylitis (AS).

METHODS

This open-label extension study recruited patients with AS who completed a 54-week, randomised controlled study comparing CT-P13 with RP (PLANETAS). CT-P13 (5 mg/kg) was administered intravenously every 8 weeks from week 62 to week 102. Efficacy end points included the proportion of patients achieving Assessment of SpondyloArthritis international Society (ASAS)20. Antidrug antibodies (ADAs) were measured using an electrochemiluminescent method. Data were analysed for patients treated with CT-P13 in the main PLANETAS study and the extension (maintenance group) and those who were switched to CT-P13 during the extension study (switch group).

RESULTS

Overall, 174 (82.9%) of 210 patients who completed the first 54 weeks of PLANETAS and agreed to participate in the extension were enrolled. Among these, 88 were maintained on CT-P13 and 86 were switched to CT-P13 from RP. In these maintenance and switch groups, respectively, ASAS20 response rates at week 102 were 80.7% and 76.9%. ASAS40 and ASAS partial remission were also similar between groups. ADA positivity rates were comparable (week 102: 23.3% vs 27.4%). Adverse events led to treatment discontinuation during the extension study in 3 (3.3%) and 4 (4.8%) patients, respectively.

CONCLUSIONS

This is the first study to show that switching from RP to its biosimilar CT-P13 is possible without negative effects on safety or efficacy in patients with AS. In the maintenance group, CT-P13 was effective and well tolerated over 2 years of treatment.

TRIAL REGISTRATION NUMBER

NCT01571206; Results.

Biosimilars Are Here: A Hospital Pharmacist's Guide to Educating Health Care Professionals on Biosimilars

BACKGROUND

Pharmacists are the recognized experts in pharmacotherapy. With the recent introduction of biosimilar agents into the US market, pharmacists are poised to play a pivotal role in evaluating their risks versus benefits within the framework of cost containment.

PURPOSE

This article provides hospital pharmacists with the necessary information on the principles surrounding the development, approval process, and use of biosimilars.

METHODS

Information contained in this article enables hospital pharmacists to identify concerns relating to biosimilars, implement educational components, and successfully evaluate biosimilars for the addition to the formulary. Additionally, this article reviews the European experience with biosimilars, the US Food and Drug Administration approval process, and postauthorization safety and pharmacovigilance programs.

CONCLUSION

It is important to educate health care providers about the differences between biosimilars and their reference biologics. The adoption of biosimilars is necessary to control long-term costs of biologics, increase patient access to care, and encourage innovation.

Biosimilar ESAs: a comparative review

BACKGROUND

The management of anaemia in patients with chronic kidney disease has been transformed by development of erythropoiesis-stimulating agents (ESAs). Following expiry of the patent of the originator epoetin alfa in Europe, a number of biosimilar ESAs have been licensed for use in the nephrology setting. Biosimilars are biological medicines that are approved via stringently defined regulatory pathways on the basis that they have demonstrated comparable safety, efficacy and quality to their reference product.

OBJECTIVES

As nurses have a pivotal role in patient care, not only administering medications but also educating patients about their treatment options, it is important that nurses understand the differences between biosimilar medicines and their reference products and appreciate the stringent regulatory requirements for approval of biosimilars.

METHODS

In this review, we use epoetin zeta as a case study to highlight practical considerations of using biosimilar ESAs in the management of patients with kidney disease.

RESULTS AND CONCLUSION

Biosimilar products, such as epoetin zeta, may offer a range of features to patients, nurses and physicians, such as greater flexibility over dose and route of administration, in addition to greater access to biological medicines through cost savings.

APPLICATION TO PRACTICE

Renal nurses play a significant role in the management of patients with kidney disease and anaemia, not only having an important role in the delivery of medicine but also in the education of patients. This review discusses some of the practical aspects associated with the use of biosimilar medicines to assist nurses in making informed decisions over their use.

Efficacy of subcutaneous epoetin-zeta on anemia in renal transplant recipients: a single-center experience

BACKGROUND

Persistent or "de novo" anemia (plasma hemoglobin<11 g/dL) may complicate the graft outcome in a significant number of renal transplant recipients. We describe a single-center experience with epoetin-zeta (EPO-Z), the biosimilar form for epoetin-alfa.

METHODS

Twenty patients were included in the study, 10 in treatment with different erythropoiesis-stimulating agents (ESA) and shifted to EPO-Z (shift group) and 10 who started EPO-Z treatment for anemia (naive group). All the patients had stable renal function and normal values of main inflammation markers and were prospectively followed up for 12 months. Iron supplements were administered during the study, as needed.

RESULTS

In the shift group, mean plasma hemoglobin levels>11 g/dL were maintained for the entire 1-year follow-up period, with average EPO-Z doses 3.4% higher than the corresponding doses of previous ESA; in the naive group, the target value was reached between the first and third months and remained stable throughout the study. Mean corpuscular volume did not vary in either group. No change was observed in glomerular filtration rate, nor in proteinuria or in main laboratory data. No drug-related side effect was reported.

CONCLUSIONS

EPO-Z may be considered a valid alternative to different ESAs in renal transplant recipients, with an interesting pharmaco-economic profile, considering its lower cost.

The approval process for biosimilar erythropoiesis-stimulating agents

A biosimilar drug or follow-on biologic drug is defined by the Public Health Service Act as a product that is "highly similar to the reference product notwithstanding minor differences in clinically active components and there are no clinically meaningful differences between the biologic product and the reference product in terms of the safety, purity and potency of the product." The advantage of biosimilar drugs is that they are significantly less expensive than the reference products, allowing for increased accessibility and cost savings. Recognizing these advantages, the US Congress passed the Biologics Price Competition and Innovation Act in 2009 as part of health care reform. The Biologics Price Competition and Innovation Act allows sponsors of biosimilar agents to seek approval by showing structural and functional similarity to the reference agent, with the extent of required clinical studies to be determined on the basis of the degree of biosimilarity with the reference product. The goal is to bring biosimilar agents to the market more efficiently while still protecting the safety of the public. The European Union has had such a process in place for a number of years. Two biosimilar epoetin agents have been approved in the European Union since 2007, and their companies are conducting trials to seek approval in the United States, because Amgen's patent protection for epoetin alfa expires in 2014. Trials completed for European Union approval of both agents showed similar efficacy and safety to the reference epoetin alfa. As with all biologics, immunogenicity concerns may persist because of the fragility of the manufacturing process and the worldwide experience with pure red cell aplasia as a result of epoetin therapy. The uptake of biosimilar epoetins after approval in the United States will depend on the balance of cost advantage against safety concerns. Competition in the marketplace will likely decrease the cost of the reference agent as well.

Biosimilars in the therapy of inflammatory bowel diseases

A biosimilar is a copy of an approved biological medicine whose patent protections have expired. Biosimilars of antibodies to tumour necrosis factor α (TNFα) are becoming important in the treatment of inflammatory bowel diseases (IBD). The first one introduced commercially is an infliximab biosimilar. The aim of this study was to provide an overview of anti-TNFα biosimilars. The literature on biosimilars of monoclonal anti-TNFα antibodies was reviewed, including their manufacture and approval pathways, concerns about efficacy, safety, immunogenicity, extrapolation, switching and labelling. Previous experience with biosimilars of epoetin and other growth factors was also reviewed. The infliximab biosimilar CT-P13 was the first biosimilar monoclonal antibody registered for the treatment of IBD. The major advantage of biosimilars is the reduced cost of therapy. Concerns have arisen, however, about the efficacy and safety of CT-P13 in IBD, the extrapolation of results from rheumatologic trials to IBD and the free interchangeability of CT-P13 with infliximab. Experience with simple peptide biosimilars, such as epoetins and growth factors, has generally been positive, with these biosimilars having similar efficacy and safety as the original products, although immunogenicity remains a major concern. Upcoming postregistration studies will address concerns on biosimilars in IBD, including their efficacy, safety, immunogenicity, switching and interchangeability. Biosimilars active against the same epitopes, but with improved pharmacokinetic properties that enhance their efficacy and/or safety, may be the next stage in the development of biosimilars. Anti-TNFα biosimilars represent promising new treatment options for patients with IBD. However, data on their efficacy and safety in IBD are needed.

Epoetin zeta in the management of anemia associated with chronic kidney disease, differential pharmacology and clinical utility

Epoetin zeta was granted marketing authorization in October 2007 by the European Medicines Agency as a recombinant human erythropoietin erythropoiesis-stimulating agent to treat symptomatic anemia of renal origin in adult and pediatric patients on hemodialysis and adults on peritoneal dialysis, as well as for symptomatic renal anemia in adult patients with renal insufficiency not yet on dialysis. Currently, epoetin zeta can be administered either subcutaneously or intravenously to correct for hemoglobin concentrations ≤10 g/dL (6.2 mmol/L) or with dose adjustment to maintain hemoglobin levels at desired levels not in excess of 12 g/dL (7.5 mmol/L). This review article focuses on epoetin zeta indications in chronic kidney disease, its use in managing anemia of renal origin, and discusses its pharmacology and clinical utility.

Efficacy and safety data of subsequent entry biologics pertinent to nephrology practice: a systematic review

Background

Subsequent entry biologics (SEBs) may soon be a reality in Canadian nephrology practice. Understanding the worldwide experience with these agents will be valuable to Canadian clinicians.

Objectives

To compare the efficacy and safety data between SEBs used in nephrology practice and their reference biologic.

Design

Systematic review.

Sources of information

Ovid MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Review of Effects, Cochrane Central Register of Controlled Trials.

Patients

Adult patients with chronic kidney disease (CKD).

Methods

Our systematic review follows the process outlined by Cochrane Reviews. For efficacy data, all randomized controlled trials (RCTs), quasi-RCTs and observational trials in nephrology practice were included. For safety data, case series, case reports, review articles in nephrology practice and pharmacovigilance programs were included as well.

Results

Only epoetin SEBs trials were published in the literature. Ten studies involving three different epoetin SEBs (epoetin zeta, HX575 and epoetin theta) were included. The mean epoetin dose used did not differ significantly between the SEBs and the reference product. For epoetin zeta and epoetin theta, the mean hemoglobin levels achieved in the studies were similar between the SEBs and the reference epoetin. The HX 575 studies reported a mean absolute change in hemoglobin within the predefined equivalence margin, when compared with the reference biologic. In terms of safety data, 2 cases of pure-red-cell aplasia were linked to the subcutaneous administration of HX 575. Otherwise, the rate of adverse drug reactions was similar when epoetin SEBs were compared with the reference biologic.

Limitations

Our analysis is limited by the paucity of information available on SEB use in nephrology with the exception of epoetin SEBs. Methodological flaw was found in one of the epoetin zeta studies which accounted for 45% of pooled results.

Conclusions

Little clinical difference was found between epoetin SEBs and the reference product. Although not deemed clinically important, the financial implication of a possible dose difference between epoetin zeta and reference product should be considered in pharmacoeconomic studies. Ongoing trials are expected to address the risk of pure-red-cell aplasia with HX 575.

Epoetin biosimilars in Europe: five years on

Biosimilars have been developed for several biologic therapeutic agents, including erythropoiesis-stimulating agents (ESAs). However, biosimilars cannot be assumed to be completely identical to the reference product, nor can two different biosimilars of the same reference product be considered equivalent. Accordingly, standards for approving biosimilars are distinct from those for generic versions of conventional pharmaceuticals.By late 2007, two biosimilar epoetins (HX575 and SB309) had been approved by the European Medicines Agency (EMA), following a series of pharmacokinetic and pharmacodynamic equivalence studies, as well as phase 3 clinical comparability evaluations. Additionally, the results of a limited number of postauthorization interventional or observational studies and quality comparisons were published subsequently on both products.The reported differences in glycosylation profiles between these epoetin biosimilars and their reference product, as well as the lack of long-term safety and efficacy evaluation, could indicate a need to develop a more comprehensive analysis of the available data, and to evaluate the post-authorization real-life data, in order to gain a better understanding of any potential implications of molecular structural or formulation differences on longterm safety and effectiveness.Switching between an original reference ESA and a biosimilar (and possibly also switching between biosimilar versions of the same product) should be regarded as a change in clinical management. Clinicians need to be fully involved in such decisions. Prescribing by brand name will prevent unintentional substitution by pharmacists and allow for effective pharmacovigilance, in accordance with recent EU directives. In this review, the authors have analyzed most of the published information on the two epoetin biosimilars, HX575 and SB309, to highlight the points that healthcare providers may need to consider when assessing an epoetin biosimilar.