Monoclonal antibody aggregates: physicochemical characteristics, stability in biological fluids and immunogenicity

Therapeutic proteins have become invaluable in treating a wide range of serious and life-threatening diseases. However, repeated administration of these drugs to patients often induces the formation of undesirable anti-drug antibodies, also known as immunogenicity. Among the factors that are known to play a role in immunogenicity of therapeutic proteins, the presence of protein aggregates has been indicated as one of the main product-related risk factors. Even though several studies have shown that protein aggregates have the propensity to trigger an antibody response against the monomeric form of the protein, little is known about the particularities that make them immunogenic. The work presented in this thesis focuses mainly on aggregate characterization and aggregate-related immunogenicity of monoclonal antibody formulations, using a monoclonal human IgG1 with k light chains as a model. The use of emerging analytical techniques for the characterization of IgG aggregates is evaluated; non-native aggregation mechanisms of IgG are studied; the fate of fluorescently labeled IgG aggregates upon contact with human biological fluids in vitro and upon injection in mice is investigated; and the correlation between type and amount of IgG aggregates with their immunogenic potential is studied in transgenic mice (containing the human genes for Ig heavy and light chains) and their nontransgenic counterpart