PandA (PEG and acid) assay

The administration of biological therapeutics has the potential to induce undesirable immunogenicity, resulting in anti-drug antibodies (ADA) which may lead to allergic reactions, altered pharmacokinetics (PK) and reduced efficacy. The biotherapeutics with long half-life or high dosing or the targets may interfere with the detection of ADAs causing false negative (from drug) or false positive results (from target). To overcome these limitations, a precipitation and acid dissociation assay, also called PEG and acid (PandA) assay has been developed. The method aims to detect total ADA (free ADA and drug bound ADA) in the presence of drug in samples. 

First, the samples are incubated with excess drug to saturate ADA to form drug-ADA complexes. The complexes are then precipitated using polyethylene glycol (PEG) and then subjected to an acid solution for dissociation. Free ADA (and free drug) are captured on plates and incubated with the sulfo-tagged drug for the specific detection of the ADA.