Restricted immune activation and internalisation of anti-idiotype complexes between drug and antidrug antibodies

Abstract

<jats:sec><jats:title>Objectives</jats:title><jats:p>Therapeutic antibodies can provoke an antidrug antibody (ADA) response, which can form soluble immune complexes with the drug in potentially high amounts. Nevertheless, ADA-associated adverse events are usually rare, although with notable exceptions including infliximab. The immune activating effects and the eventual fate of these ‘anti-idiotype’ complexes are poorly studied, hampering assessment of ADA-associated risk of adverse events. We investigated the in vitro formation and biological activities of ADA-drug anti-idiotype immune complexes using patient-derived monoclonal anti-infliximab antibodies.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Size distribution and conformation of ADA-drug complexes were characterised by size-exclusion chromatography and electron microscopy. Internalisation of and immune activation by complexes of defined size was visualised with flow imaging, whole blood cell assay and C4b/c ELISA.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Size and conformation of immune complexes depended on the concentrations and ratio of drug and ADA; large complexes (&gt;6 IgGs) formed only with high ADA titres. Macrophages efficiently internalised tetrameric and bigger complexes in vitro, but not dimers. Corroborating these results, ex vivo analysis of patient sera demonstrated only dimeric complexes in circulation.</jats:p><jats:p>No activation of immune cells by anti-idiotype complexes was observed, and only very large complexes activated complement. Unlike Fc-linked hexamers, anti-idiotype hexamers did not activate complement, demonstrating that besides size, conformation governs immune complex potential for triggering effector functions.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Anti-idiotype ADA-drug complexes generally have restricted immune activation capacity. Large, irregularly shaped complexes only form at high concentrations of both drug and ADA, as may be achieved during intravenous infusion of infliximab, explaining the rarity of serious ADA-associated adverse events.</jats:p></jats:sec>

The Molecular Mechanisms That Underlie the Immune Biology of Anti-drug Antibody Formation Following Treatment With Monoclonal Antibodies

“…Another possible explanation is that a strong T cellindependent immune response in the MZ may be induced by a drug/ADA/TNFα immunocomplex (IC). As a trimer, TNFα may form "super complexes" upon engagement with TNFα antagonistic antibodies (98)(99)(100).…”

2020 White Paper on Recent Issues in Bioanalysis: Vaccine Assay Validation, qPCR Assay Validation, QC for CAR-T Flow Cytometry, NAb Assay Harmonization and ELISpot Validation ( Part 3 –Recommendations on Immunogenicity Assay Strategies, NAb Assays, Biosimilars and FDA/EMA Immunogenicity Guidance/Guideline, Gene & Cell Therapy and Vaccine Assays)

“…SEC and asymmetric flow field flow fractionation (A4F) can detect CICs but provide no actual size information if not coupled to specific detectors such as Multi Angle Light Scattering (MALS). Furthermore, application of these technologies to analyze biological samples is challenging with regard to sensitivity and specificity [87,88]. There is a need to develop methods to better characterize CIC, particularly in biological samples, in terms of their size and to better understand their time of onset, structure, and their impact on PK.…”

The potential value of blood monitoring of biologic drugs used in the treatment of rheumatoid arthritis

“…It is these large complexes that produce the infusion reactions that we associate with immunogenicity: irregular-shaped large complexes trigger the complement cascade, whereas small complexes appear unable to activate complement. 6 Assay development Over the past decade, the number of available drug-monitoring and ADA-monitoring assays has grown almost proportionally to the number of TNF-alpha targeting agents. The main principle underlying TDM is the reliable measurement of available drug in the serum and, if this is proven uncharacteristically low, to assess if antibodies towards the drug have developed.…”