Evaluation of the pattern and kinetics of degradation of adalimumab using a stability-indicating orthogonal testing protocol.

Forced degradation studies are crucial for the evaluation of the stability and biosimilarity. Here, adalimumab was subjected to oxidation, pH, temperature, agitation and repeated freeze-thaw in order to generate all possible degradation products. An orthogonal stability-indicating testing protocol comprising SE-HPLC, RP-HPLC, TapeStation gel electrophoresis, dynamic light scattering (DLS), and functional receptor binding assay was developed and validated. The assay protocol was used for the assessment of the pattern and kinetics of aggregation/degradation of adalimumab. SE-HPLC and DLS were used to show the formation of aggregates/fragments of adalimumab under nondenaturing conditions. TapeStation electrophoresis was performed under denaturing conditions to reveal the nature of aggregates. Results of the receptor binding assay agreed to those of SE-HPLC and DLS which indicated that it can be used as an activity-indicating assay for adalimumab. RP-HPLC demonstrated excellent selectivity for adalimumab in the presence of its oxidized forms. The kinetics of degradation was studied in each case and the results showed that it followed the first-order reaction kinetics. Correlation between the results supported the quality assessment of the tested product in industrial and clinical settings. This orthogonal protocol is a useful tool in stability assessment of monoclonal antibodies and a key criterion for the biosimilarity assessment.