Adverse Reactions against Biologicals – Identification and Characterization of Immunogenic Epitopes and Potential Biomarkers

Background: Today there is an increase in the indication for biologicals for the treatment of various inflammatory diseases. For example, TNF-alpha blockers are used for the treatment of rheumatic disease, which also affects the lung by pulmonary hypertension and fibrosis. However, during treatment, several clinically relevant side effects occur: loss of drug efficacy, hypersensitivity and anaphylactic reactions which are mediated by IgE antibodies. These conditions lead to a discontinuation of the treatment or a switch to a different therapeutic antibody. Yet there is no existing guideline which specific therapeutic antibody should be prescribed for which patient.

Materials and Methods: In order to identify and analyze carbohydrate and peptide epitopes of biologicals, a blot-based test system for anti-biological antibodies was developed facilitating the parallel analysis of intact and processed therapeutic antibodies. Two patient cohorts with antibodies against the biologicals cetuximab and infliximab were used to prove the validity of the test system for anti-biological IgE. For the identification of peptide epitopes, a peptide microarray screening system was established for infliximab.

Results: Combined blot tests and ImmunoCAP analyses of serum from meat allergic patients reveal anti-cetuximab IgE associated with the glycosylation of cetuximab. Sera from a group of infliximab-treated patients were screened for anti-infliximab IgE. The developed test system with native and processed cetuximab/infliximab was used for the detection and characterization of anti-infliximab IgE and potential cross-reactions between the therapeutic antibodies. Furthermore, the peptide microarray screen led to the identification of six IgG epitopes on infliximab, partly located in the TNF-alpha binding region.

Conclusion: The development of versatile diagnostic platforms for the detection and characterization of peptide- and carbohydrate-specific IgE is a prerequisite for the prediction of clinically relevant IgE-mediated patient reactions against biologicals. These results shall lead to a more secure suggestion of a safer and more effective therapeutic antibody therapy.