Comparison Of Assay Methods For The Detection Of Residual Protein A In Biological Therapeutics

Protein A is used in affinity chromatography for therapeutic antibody purification. Protein A 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 provide a comparison of several suitable detection methods for the presence of residual Protein A in therapeutic biological agents including a homogenous proximity assay and conventional ELISA assay. The comparison 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 nine human IgG antibodies including the therapeutic antibodies trastuzumab, rituximab, and cetuximab for each method.