Session Information
Date: Tuesday, November 10, 2015
Title: Rheumatoid Arthritis - Small Molecules, Biologics and Gene Therapy Poster III
Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Background/Purpose: The options for treatment of rheumatoid arthritis (RA) with tumour necrosis factor (TNF) inhibitors is constantly growing. As a consequence monitoring of drug levels (DL) and Anti-Drug Antibodies (ADA) in clinical practice is advisable in order to complement clinical assessment and optimize patient treatment. However, a common objection that limits implementation of measurements in medical practice is the claim that assay standardization is lacking. The purpose of this study was to validate new assays to monitor golimumab (GLM) and antibodies to GLM (ATG), and evaluate the correlation and agreement between different commercially available technologies to monitor GLM therapy in patients with rheumatic diseases.
Methods: Trough levels of GLM and ATG were analysed in a retrospective cohort of 48 rheumatic patients (102 serum samples) initiating or under maintenance therapy with GLM for up to three years. Samples were assayed using Promonitor-GLM and Promonitor-Anti-GLM ELISA kits (Progenika, Spain), and in parallel with ELISA and radioimmunoassay (RIA) offered by Sanquin Blood Supply (Amsterdam, The Netherlands) to measure GLM levels and ATG, respectively. Promonitor tests were validated according to Clinical & Laboratory Standards Institute (CLSI) guidelines. Spearman and Mann-Whitney tests were used to study correlation and difference between the two DL tests; the difference (bias) in values obtained with both GLM assays was also assessed with Bland-Altman analysis. Percentage of positive and negative agreement was used to study the association between the ADA methods.
Results: Promonitor tests met performance criteria as recommended in the CLSI guidelines. Both types of ELISA for GLM determination showed a statistically significant relationship (Spearman´s r=0.98, p<0.0001). There was no significant difference between the two assays (median 575 vs 600 ng/mL, IQR 0 – 1614 vs 0 – 1600 ng/mL; t-test p=0.907 for Promonitor-GLM and Sanquin, respectively). Bland-Altman analysis showed a perfect agreement between both assays (bias -33.4 ng/mL 95% CI -92.3 to 25.3; p>0.05). Both tests gave identical results for ATG analysis (positive and negative percentage agreement of 100%). Antibodies were detected in 3 samples (3 patients, 6%) regardless of the test used. ELISA sensitivity proved to be equal to RIA for the detection of ATG in this cohort.
Conclusion: Validation according to CLSI guidelines proved adequate Promonitor ELISA performance for an in vitro diagnostic setting. Despite different reagents and technologies, no significant differences in GLM and ATG levels were observed between assays, suggesting that future development of optimal ranges values is viable and not influenced by the type of assay, and therefore both methods should result in similar correlations with clinical outcomes and comparable therapeutic actions.
To cite this abstract in AMA style:
Martín S, Ruiz del Agua A, Torres N, Pascual-Salcedo D, Plasencia C, Jurado T, Ruiz-Argüello B, Martínez A, Navarro R, Nagore D. Validation and Comparison Study of Immunoassays for the Measurement of Golimumab and Antibodies to Golimumab in Rheumatic Patients [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/validation-and-comparison-study-of-immunoassays-for-the-measurement-of-golimumab-and-antibodies-to-golimumab-in-rheumatic-patients/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/validation-and-comparison-study-of-immunoassays-for-the-measurement-of-golimumab-and-antibodies-to-golimumab-in-rheumatic-patients/