FRI0193 Effect of valency of anti-tnfs on elimination mediated by anti-drug antibodies

Abstract

BackgroundThere are five different anti-TNF biologics: three are bivalent full length (FL) antibodies (adalimumab, golimumab, and infliximab), one a bivalent fusion protein (etanercept), and one a univalent PEGylated Fab' (PF) (certolizumab pegol [CZP]). Administration of such protein biologics can induce anti-drug antibodies (ADAbs), of which the majority are anti-idiotypic antibodies (anti-ID).1 The potential cross-linking of bivalent anti-IDs with bivalent biologics can result in the formation of large immune complexes (ICs), which are subsequently cleared by mechanisms using the multiple Fc domains, thereby resulting in a decrease in the efficacy of the biologic. Since univalent biologics, such as CZP, only have one binding Fab' arm, such large cross-linked anti-ID-mediated ICs are unlikely to form. Therefore, anti-IDs may have a different effect on the elimination and bioavailability of univalent and bivalent biologics in vivo.ObjectivesTo determine if the valency of a biologic will affect the in vitro size and in vivo elimination from the plasma of ICs formed with an anti-ID following intravenous (IV) administration to BALB/c mice.MethodsAn anti-ID antibody to CZP was generated and used for subsequent studies to mimic an ADAb response. Univalent PF CZP was reengineered as a bivalent FL humanized IgG1 antibody (similar to adalimumab) to directly compare the effect of valency on IC-mediated clearance. This FL antibody showed very similar TNF neutralization compared to the conventional PF molecule in a bioassay. To generate ICs, the anti-ID was incubated overnight with either PF or FL CZP, and the size of the resultant ICs determined by analytical ultracentrifugation (AU). The anti-ID complexes and PF and FL CZP alone were then administered IV to the mice, and the elimination of the anti-TNFs from the circulation was monitored by quantitative liquid chromatography-mass spectrometry (LC-MS) in serial plasma samples.ResultsAU analysis of the immune complexes formed between PF CZP and the anti-ID showed the presence of one peak corresponding in size to one anti-ID molecule bound to two PF molecules (∼3.5x105 Da). In contrast, the FL CZP/anti-ID mixture showed ICs of various sizes up to very large molecular weights (>1x106 Da), with the predominant species corresponding to a complex of two anti-IDs bound to two FL CZP molecules (∼6x105 Da). The in vivo studies showed that the FL CZP/anti-ID ICs were eliminated much faster (t1/2=0.3 hours) than the FL CZP alone (t1/2=44.5 hours), whereas the PF CZP/anti-ID ICs were eliminated more slowly (t1/2=60.5 hours) than the PF CZP alone (t1/2=19.7 hours).ConclusionsThe FL CZP molecule formed large ICs with the anti-ID, which led to much faster elimination than the FL molecule alone. This result suggests that an ADAb response to a FL antibody could lead to rapid elimination and loss of efficacy of the drug in patients. In contrast, the PF CZP/anti-ID complex had a longer half-life than the PF CZP alone, presumably because this molecule was not seen as an IC due to the presence...