Monoclonal antibodies (mAbs) are invaluable in the treatment of cancers, auto-immune and inflammatory conditions. Since their advent, approximately 80 mAbs and antibody-based therapeutic products have gained marketing approval, quickly earning their positions in the list of top ten selling prescription products worldwide. One of the major challenges associated with the development of mAbs, is protein aggregation - a degradation phenomenon which results in ‘clumping’ of proteins together, and subsequent loss of protein activity. Furthermore, antibody aggregates have been associated with immunogenicity experienced by patients undergoing antibody therapy. Preventing antibody aggregation has major implications for biopharmaceutical development; not only are immunogenic reactions minimised, the shelf-life of therapeutic antibodies is significantly increased, there is increased flexibility in the type of antibody formulations that can be manufactured, and the half-life of antibodies may be increased.
We tackled the challenge of protein aggregation via two main approaches – 1) investigating novel additives and formulation approaches to suppress protein aggregation; 2) engineering structural changes to antibodies to enhance their stability and resistance to aggregation. Protein aggregation was characterised using intrinsic and extrinsic fluorescence, size-exclusion-HPLC and light scattering techniques. This orthogonal approach allowed us to probe the conformational and colloidal stability of the protein at every step in the aggregation process.
Successful approaches discovered include the use of ionic liquids as stabilizers, and engineering antibodies with additional glycosylation to improve their conformational stability. The work described in this thesis paves the way for the development of next-generation therapeutic antibodies, or biobetters, which are resistant to aggregation.