Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Immunology, NECROSIS-FACTOR-ALPHA, ANTI-INFLIXIMAB ANTIBODY, ANKYLOSING-SPONDYLITIS, RHEUMATOID-ARTHRITIS, DISEASE-ACTIVITY, IMMUNOGENICITY, HARMONIZATION, PHARMACOKINETICS, BIOAVAILABILITY, ANTAGONISTS, Antibodies, Blocking, Antibodies, Monoclonal, Enzyme-Linked Immunosorbent Assay, Etanercept, Humans, Hybridomas, Monitoring, Physiologic, Observer Variation, Severity of Illness Index, Spondylitis, Ankylosing, Tumor Necrosis Factor-alpha, 1107 Immunology, 3101 Biochemistry and cell biology, 3204 Immunology

Abstract:

The clinical response in ankylosing spondylitis (AS) patients treated with biologic agents can be influenced by pharmacokinetic variability among and within these patients. Therapeutic drug monitoring is seen as a valuable tool to improve patient care. The aim of this study was to generate a panel of mAbs toward etanercept (ETN) and to determine ETN and anti-ETN concentrations in AS patients. mAbs against ETN (MA-ETN) were generated using hybridoma technology. For quantification of ETN concentrations, a mAb-based TNF-coated ELISA and a mAb/mAb-based sandwich-type ELISA were developed. For evaluation of the anti-ETN Ab response, a bridging ELISA, as well as a functional cell-based assay, were constructed. Disease activity of the AS patients was measured with the AS Disease Activity Score (ASDAS). Active disease was defined as ASDAS >= 2.1. A total of 59 of 76 generated mAbs were ETN specific and were characterized further. Fifty-one mAbs revealed inhibitory properties in a cell-based assay. Analysis of serum concentrations of 21 ETN-treated AS patients with the TNF/MA-ETN68C5-HRP ELISA and the MA-ETN63C8/MA-ETN61C1-HRP ELISA revealed a good Pearson’s r (+0.974) but a poor intraclass correlation coefficient (+0.528) as the result of underestimation of the values in the former ELISA. At 24 wk, ETN concentrations were similar in patients with ASDAS < / 2.1 and >= 2.1. Anti-ETN Abs were not detected in any of the patient samples tested. In conclusion, highly sensitive mAb-based immunoassays were developed for quantification of ETN and anti-ETN concentrations. The impact of these methods needs to be evaluated further in clinical practice.