Preexisting antibodies to an F(ab′)2 Antibody therapeutic and novel method for immunogenicity assessment

Anti-therapeutic antibodies (atas) may impact drug exposure and activity and induce immune complex mediated toxicity; therefore the accurate measurement of ata is important for the analysis of drug safety and efficacy. preexisting atas to the hinge region of anti-delta like ligand 4 (anti-dll4) f(ab′)2,a potential antitumor therapeutic,were detected in cynomolgus monkey serum,which presented a challenge in developing assays for detecting treatment induced ata. a total ata assay was developed using a bridging elisa that detected both anti-cdr and anti-framework ata including anti-hinge reactivity. a competition assay that could detect 500 ng/ml of anti-cdr ata in the presence of preexisting ata was also developed to determine ata specific to the anti-dll4 f(ab′)2 cdr using anti-dll4 f(ab′)2 and a control f(ab′)2. we used these assay methods in a cynomolgus monkey in vivo study to successfully evaluate total and anti-cdr ata. the preexisting anti-hinge reactivity was also observed to a lesser extent in human serum,and a similar approach could be applied for specific immunogenicity assessment in clinical trials. © 2016 jane ruppel et al.