Assessment of methods for determination of glycan composition of erythropoietin.

Erythropoietin (EPO) is a monomeric, highly glycosylated, protein hormone (molecular size around 30-35 kD), produced mainly in adult kidneys, which acts principally on red blood cell progenitors and precursors to promote red cell production. Therapeutic EPO products are widely used biotherapeutics. They are mainly produced by recombinant DNA technology in mammalian cells and their biological activity is closely linked to the degree of N-glycan sialylation. Determination of the sialic acids' content and complexity by glycan mapping therefore appears critical to ensure the quality and efficacy of the EPO therapeutic products. The European Directorate for the Quality of Medicines & HealthCare organised a study (BSP144) under the aegis of the Biological Standardisation Programme to assess N-glycan mapping tests with the aim of incorporating a standard method into the European Pharmacopoeia monograph 'Erythropoietin concentrated solution' (1316). The use of a 'reagent panel' consisting of six EPO preparations with a range of iso-electric properties facilitated comparison between laboratories and methodologies. Based on the study results, a robust and repeatable HPAEC-PAD chromatographic method was identified and work to introduce it in the monograph as an example method has been initiated.

Quality and Batch-to-Batch Consistency of Original and Biosimilar Epoetin Products.

Comprehensive physicochemical characterization and biological assays are essential parts in assessing quality attributes of biologicals. Here, we compared the quality of different marketed recombinant human erythropoietin (epoetin) products: originators, Eprex and NeoRecormon as well as 2 biosimilars, Retacrit and Binocrit. In addition, assessment of batch-to-batch variability was included by collecting 2 or more batches of each product. Common assays which included sodium dodecyl sulfate-polyacrylamide gel electrophoresis, high-performance size-exclusion chromatography, asymmetrical flow field-flow fractionation, capillary zone electrophoresis, and potency testing were used. Of the tested products and among batches of single products, variations in epoetin content, isoform profiles, and potency were found. Ultimately, this study demonstrated the high quality of epoetin products with some degree of variation among products and batches, confirming the "similar but not identical" paradigm of biologicals.

An Integrated Approach for a Structural and Functional Evaluation of Biosimilars: Implications for Erythropoietin.

BACKGROUND: Authorization to market a biosimilar product by the appropriate institutions is expected based on biosimilarity with its originator product. The analogy between the originator and its biosimilar(s) is assessed through safety, purity, and potency analyses. OBJECTIVE: In this study, we proposed a useful quality control system for rapid and economic primary screening of potential biosimilar drugs. For this purpose, chemical and functional characterization of the originator rhEPO alfa and two of its biosimilars was discussed. METHODS: Qualitative and quantitative analyses of the originator rhEPO alfa and its biosimilars were performed using reversed-phase high-performance liquid chromatography (RP-HPLC). The identification of proteins and the separation of isoforms were studied using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and two-dimensional gel electrophoresis (2D-PAGE), respectively. Furthermore, the biological activity of these drugs was measured both in vitro, evaluating the TF-1 cell proliferation rate, and in vivo, using the innovative experimental animal model of the zebrafish embryos. RESULTS: Chemical analyses showed that the quantitative concentrations of rhEPO alfa were in agreement with the labeled claims by the corresponding manufacturers. The qualitative analyses performed demonstrated that the three drugs were pure and that they had the same amino acid sequence. Chemical differences were found only at the level of isoforms containing N-glycosylation; however, functional in vitro and in vivo studies did not show any significant differences from a biosimilar point of view. CONCLUSION: These rapid and economic structural and functional analyses were effective in the evaluation of the biosimilarity between the originator rhEPO alfa and the biosimilars analyzed.