Automation Of A Homogeneous Proximity Assay For Detection Of Residual Protein A In Biological Therapeutics

By Peter J. Brescia and Peter Banks, Applications Department, BioTek Instruments, Inc.

Protein A is used in affinity chromatography for therapeutic antibody purification and has been shown to leach from columns during purification of antibodies resulting in contamination. Residual Protein A in therapeutic drugs could elicit mitogenic or immunological reactions in patients. Therefore, there are strict FDA guidelines regarding acceptable levels of Protein A in antibody preparations intended for use as therapeutics. Given the prevalence of biologics in the current drug development pipeline, highly sensitive and robust quantification methods amenable to HTS are desirable. Here we demonstrate automation of a HTS compatible homogenous proximity assay for the presence of residual Protein A in biological therapeutics using AlphaLISA technology. The demonstration includes evaluation of the lower detection limit (LDL) of Protein A as well as screening results for detection of residual Protein A in a panel of ten human IgG antibodies including the therapeutic antibodies Herceptin®, Rituxan®, and Erbitux®.