Product losses through the formation of aggregates are still a major problem at each stage of a therapeutic protein’s life, from its effects on expression within the cell through to the shelf life of the packaged product. These aggregates are typically undesirable since they are a manifestation of the target molecules physical instability and result in both reduced activity and increased immunogenic potential. Aggregates can form both in liquid and solid states via numerous reaction pathways driven by both intrinsic factors, principally the polypeptide sequence, as well as external factors including ionic strength, pH and temperature to name but a few. The resultant agglomerates can develop over highly variable timescales, exhibiting a multitude of final morphologies with varying degrees of reversibility. Though mechanisms behind this transformation have been a research topic for over fifty years, little is still known about how the initial conditions of the protein system governs the molecules propensity to aggregate. The aim of this study is to characterise the aggregation behaviour of a previously unstudied commercial therapeutic protein, a Fab’ antibody fragment, and investigate whether this can be correlated with empirical data collected under comparable conditions. By combining analyses of local changes to the molecule, for instance alterations in the conformational stability or structure, with bulk measurements such as the net colloidal interaction, one can begin to describe the competing aggregation mechanisms occurring and their relative importance depending upon the initial conditions of the system. Through gaining a better understanding of the molecular processes occurring, combined with quantitative data relating changes in both a protein and its environment to measurable features of the system and its subsequent aggregation propensity, it ought to be possible to begin using this information as a flexible parameter when optimising bioprocessing conditions or designing longer term pharmaceutical formulations.

Can aggregation prone states of an antibody fragment be predicted through biophysical analysis?

249th National Meeting (2015)

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