Aggregation

Aggregation refers to the molecular assembly of protein monomers into larger multimeric structures through non-covalent or covalent interactions, representing one of the most critical quality challenges in therapeutic protein development. Unlike simple particle clustering, aggregation involves specific intermolecular forces that alter protein structure, potentially triggering immunogenic responses, reducing biological activity, and compromising patient safety. This complex phenomenon affects virtually all protein-based therapeutics, from monoclonal antibodies to recombinant enzymes and vaccines.

The biopharmaceutical industry invests extensively in understanding and mitigating aggregation throughout drug substance and drug product lifecycles. Aggregates form through multiple pathways including thermal stress, oxidation, deamidation, and interface-induced perturbations during manufacturing operations like freeze-thaw cycles or vigorous mixing. Regulatory agencies require comprehensive aggregate characterisation using orthogonal analytical methods such as size-exclusion chromatography, field-flow fractionation, and advanced imaging techniques. Formulation scientists optimise buffer systems, pH conditions, and stabilising excipients to minimise aggregation propensity while maintaining long-term stability. The growing biosimilar market intensifies focus on demonstrating aggregate comparability to reference products. As novel formats emerge, including bispecific antibodies, antibody fragments, and multi-specific constructs, aggregation assessment becomes increasingly sophisticated, demanding integrated analytical strategies and predictive modelling approaches that anticipate aggregation behaviour under diverse stress conditions.