Objectives. In this biosimilar research, we compare the monoclonal antibody eculizumab obtained from different drugs [original Soliris^® (Alexion Pharmaceuticals) and candidate Elizaria^® (Generium)] by intact mass measurement and middle-up mass spectrometry analysis to enhance the role of mass spectrometry methods in biopharmaceutical development processes.Methods. The intact mass measurement is performed using a high-resolution ESI-MS. The middle-up analysis is performed by reversed-phase high-performance liquid chromatography with ESI-MS detection, subsequent IdeS treatment of antibodies, and disulfide bond reduction.Results. We have shown some small differences between the original and candidate drugs in the minor glycans level. Man5 glycan is only found in the original Soliris, and G0 is only found in the Elizaria. Glycation sites are also found in the light chain and Fd subunits of the original Soliris. The glycation level does not exceed 4.4%. The non-clipped C-end lysine level and G0F glycan levels are slightly lower in the original Soliris. All registered differences are not crucial for eculizumab’s quality and do not affect its effectiveness and preclinical safety. Generally, the results show a high level of similarity between the original and candidate drugs.Conclusions. The comparative mass spectrometry analysis of eculizumab in the original Soliris and Elizaria allows us to estimate their high degree of similarity by molecular masses and major modification profiles.

The disfunction or deficiency of the C1 esterase inhibitor (C1INH) is associated with hereditary or acquired angioedema (HAE/AAE), a rare life-threatening condition characterized by swelling in the skin, respiratory and gastrointestinal tracts. The current treatment options may carry the risks of either viral infection (plasma-derived Berinert^®) or immune reaction (human recombinant C1INH from rabbit milk, Ruconest^®). This study describes the physicochemical and biological characterization of a novel recombinant human C1 esterase inhibitor (rhC1INH) from Chinese hamster ovary (CHO) cells for the treatment of hereditary angioedema compared to the marketed products Berinert^® and Ruconest^®. The mass spectrometry results of total deglycosylated rhC1INH revealed a protein with a molecular mass of 52,846 Da. Almost full sequence coverage (98.6%) by nanoLC-MS/MS peptide mapping was achieved. The purity and C1s inhibitory activity of rhC1INH from CHO cells are comparable with Ruconest^®, although we found differences in charge isoforms distribution, intact mass values, and N-glycans profile. Comparison of the specific activity (IC₅₀ value) of the rhC1INH with human C1 esterase inhibitor from blood serum showed similar inhibitory properties. These data allow us to conclude that the novel rhC1INH molecule could become a potential therapeutic option for patients with HAE/AAE.

Peptide mapping is a key method for studying the primary structure of proteins. With its sensitivity to the slightest changes in the covalent structure of a protein, this method is applicable both to medicinal product identification at the control stage and to production process stability monitoring.The aim of the study was to develop and validate a peptide-mapping procedure for the identification of a novel highly glycosylated recombinant C1 esterase inhibitor.Materials and methods. The authors studied recombinant human C1 esterase inhibitor products and trypsin. The study involved peptide mapping using reverse-phase high-performance liquid chromatography and high-resolution mass spectrometry. The following statistics were calculated to evaluate the results: mean, standard deviation, and coefficient of variation. The validation parameters included specificity, precision, and robustness.Results. The authors tested several variants of sample preparation for tryptic digests, including additional N-glycanase treatment and complete deglycosylation, and established the optimal conditions for sample preparation and chromatographic separation of C1 esterase inhibitor peptides to obtain consistent chromatographic profiles (peptide maps). The authors identified characteristic peaks and the corresponding relative retention time and area ranges. The absolute retention time of the second (characteristic) peak was approximately 16.5–16.9 minutes. The relative retention times were 2.14–2.21 for peak 9, 2.55–2.64 for peak 12, 2.97–3.14 for peak 14, 3.11–3.29 for peak 15, and 6.20–6.63 for peak 28.Conclusions. The authors developed a peptide-mapping procedure for C1 esterase inhibitors and optimised the conditions to achieve an over 18-hour reduction in sample preparation time. This procedure met the established acceptance criteria for specificity, precision, and robustness.

Medicines based on recombinant human interferons (rhIFNs) beta-1a and beta-1b are used as first-line treatment of multiple sclerosis. Meanwhile, rhIFN beta-1a and beta-1b have structural differences associated with the eukaryotic or prokaryotic expression systems, respectively. Pharmacopoeias require identification of the primary structure of recombinant proteins by peptide mapping, which involves the use of reference material. Currently, there is no international reference standard available for rhIFN beta-1b structural identification. The aim of the study was development and certification of a pharmacopoeial reference standard for identification of the amino acid sequence of purified rhIFN beta-1b by peptide mapping. Materials and methods: rhIFN beta-1b produced by GENERIUM and endoproteinase Glu-C from Staphylococcus aureus V8 were used in the study. The peptide mapping was performed using reverse-phase high-performance liquid chromatography (RP HPLC) and high-resolution mass spectrometry. Statistical evaluation of the results included calculation of the arithmetic mean, standard deviation, and coefficient of variation. Results: the authors developed and certified a Russian Pharmacopoeia reference standard for structural identification of rhIFN beta-1b (PhRS 3.2.00447). The certified characteristic is the range of retention times of characteristic peaks: the absolute retention time was 42.0–43.2 for the third (reference) peak, the relative retention time was 0.61–0.66 for the first peak, 0.68–0.73 for the second peak, 1.04–1.06 for the fourth peak, 1.14–1.15 for the fifth peak, 1.22–1.24 for the sixth peak, and 1.29–1.30 for the seventh peak. Conclusions: the authors developed requirements for the rhIFN beta-1b pharmacopoeial reference standard. The material chosen as the candidate reference standard was an intermediate rhIFN beta-1b product sampled before addition of human serum albumin. The quality control was carried out in accordance with the developed specification. The authors analysed the amino acid sequence of the molecule, confirmed the presence of the disulfi e bond, and obtained the certifi d characteristic of the reference standard. Comparative analysis of the peptide maps of the certified rhIFN beta-1b pharmacopoeial reference standard and the rhIFN beta-1a reference standard revealed differences between the maps, and, therefore, confirmed the relevance of the developed reference standard.