Andrea Ferrante, MD, Principal Research Scientist, Eli Lilly and Company
Presence of pre-existing antibodies (PRA) to biotherapeutic proteins in drug-naïve individuals is a known phenomenon, of which clinical consequence ranges from no impact to serious adverse effect depending on multiple factors, including but not limited to, drug modality, indication, and subject-specific background. Although evidence for the presence of pre-existing antibody has been initially identified during anti-drug antibody assay development, quantification of PRA incidence in drug-naïve population has become one of the components of preclinical immunogenicity risk assessment strategies. The routine approach to PRA measurement is usually in the form of an ELISA-based assay, in which drug-naïve donors’ diluted serum is co-incubated with the drug in a bridge or sandwich modality. Here we report a novel method, which is based on a surface plasmon resonance (SPR)-measurement of the test molecule binding to immunoglobulins (Ig) purified from drug-naïve subjects’ sera. Isolation of the Ig and concentration normalization eliminates matrix effect and enables comparison across subjects. By using a high-density surface, PRA of a wide range of affinity to the test molecule can be identified, making this approach a sensitive alternative to the ELISA-based methods, and enabling definition of their Ig isotype. The procedure can be performed in a semi-automated fashion to increase efficiency and throughput, and an extensive qualification of the platform shows that this approach is a viable option for including assessment of PRA in a pre-clinical immunogenicity assessment plan.