Antibody Affinity

Antibody Affinity designates the strength of the non-covalent binding interaction between an antibody's antigen-binding site and its specific epitope, quantified by equilibrium dissociation constants reflecting the ratio of dissociation to association rate constants. Higher affinity antibodies bind more tightly and may demonstrate superior therapeutic potency and selectivity.

The biopharmaceutical industry characterises antibody affinity extensively during discovery, development, and quality control using techniques including surface plasmon resonance, bio-layer interferometry, and isothermal titration calorimetry providing association rates, dissociation rates, and equilibrium constants. Affinity requirements vary by application, with receptor-blocking antibodies potentially requiring picomolar affinities while tumour antigen-targeting antibodies balance affinity with appropriate dissociation enabling cellular uptake of antibody-drug conjugate payloads. Affinity maturation campaigns routinely improve initial antibody affinities by several orders of magnitude. Regulatory submissions include affinity characterisation as part of product identity and potency documentation. As novel therapeutic formats emerge, affinity engineering continues enabling optimised target engagement.