Study Reports on Analytical Characterization of Biosimilar Adalimumab SB5

Newly published research reports on an analytical characterization of Samsung Bioepis’ biosimilar adalimumab, SB5 (licensed in the European Union as Imraldi and in the Republic of Korea as Hadlim), in comparison with the reference, Humira, using 3 different guidelines, showed that the 2 products are largely similar, and any of the minor differences are not clinically meaningful. These data were part of regulatory submissions that led to the product’s approval.

The researchers said they followed the FDA, International Conference on Harmonization, and European Medicines Agency guidelines in their analysis.

Structural, physicochemical, and biological quality attributes critical to adalimumab’s mechanism of action and with a potential to affect potency, efficacy, and safety were selected.

SB5 and Humira were then analyzed using more than 55 methods. Researchers used all available batches of SB5 and more than 100 EU- and US-sourced lots of Humira and compared the 2 sets of data. The structural properties comprised primary and higher-order structures and N-glycosylation. The physicochemical characteristics were categorized into liquid chromatographic patterns and electrophoretic pattern concerning size and charge heterogeneity. The biological properties were examined by in vitro functional assays.

No notable differences were found between the 2 products when examining the primary structure, disulfide linkage, higher-order structure, carbohydrate structure and composition, size heterogeneity, charge heterogeneity, and biological activities.

A structure-activity relationship study (SAR) was performed for 2 types of variation, NGHC and charge variants. The variants present in the fractions of different charged species were identified and studied for biological activity as part of the SAR studies. For identification of the charged variants, samples can be fractionated using liquid phase isoelectric focusing (IEF) and CEX-HPLC.

CEX-HPLC was conducted to fractionate and investigate the charge heterogeneity of SB5 and of the reference product. Each fraction was analyzed using intact mass and peptide mapping analysis. Intact mass analysis was performed to determine glycation, C-terminal lysine variant, and other PTMs including fragmentation.

Peptide mapping was performed to determine sialylation, oxidation, deamidation, α-amidation, N-terminal pyro-E, and C-terminal lysine variant. Results from intact mass analysis showed that identical molecular weight of the intact form was observed in all fractions of SB5 and the reference product, considering assay variability.

Results from peptide mapping showed that similar levels of oxidation, deamidation, and N-terminal pyro-E form were observed in all fractions of SB5 and the reference product, considering assay variability. There is no significant difference between fractions of SB5 and reference products in terms of the level of those PTMs.

Lysine on C-terminus of the heavy chain was identified as the main difference in the basic fractions. SAR study results for the lysine variants showed that the basic variants have no effect on the biological activities of both SB5 and the reference product.

In the acidic fraction, samples were identified as containing sialylated N-glycan peptides using liquid chromatography with tandem mass spectrometry. In alignment with SAR study results for acidic charge variant, percentage of charged glycan (percentage of sialylation) level by 2-AB labelled N-glycan analysis in SB5 (2.3%-3.5%) was slightly higher than that in the reference product (0.2%-0.7%). It was concluded that this result was caused by the terminal sialic acid on N-glycan species.

In addition, a SAR study was performed to rule out any negative effects of the difference in charged on the efficacy of adalimumab. The results demonstrated that there was no difference in neonatal Fc receptor binding, tumor necrosis factor (TNF) binding, and antibody-dependent cellular toxicity activity between sialylated and non-sialylated adalimumab.

In summary, the minor differences in acidic variants and basic variants would not be expected to affect the efficacy and safety of SB5 and the reference product.

Finally, SB5 showed similar efficacy in terms of TNF binding and neutralizing potency. The main mechanisms of action of adalimumab, binding to TNF, as well as TNF-neutralizing potency, were found to be highly similar between SB5 and the reference product.

Overall, SB5 and Humira were shown to be similar to each other in terms of quality attributes. The differences in some physicochemical attributes, such as the charge variants, are not considered to have a significant role in the biological function of the antibody based on SAR studies.

SB5 safety, purity, and potency are not affected by minor differences, the researchers said.

Reference

Lee N, Lee, JJ, Yang H, et el. Evaluation of similar quality attribute characteristics in SB5 and reference product of adalimumab [published online October 19, 2018]. mAbs. doi: 10.1080/19420862.2018.1530920.