Detection of anti-adalimumab antibodies in a RA responsive cohort of patients using three different techniques

Reliable monitoring of clinical relevant anti-drug antibodies is fundamental in the follow-up of patients under adalimumab treatment. The aim of this study is to compare anti-adalimumab antibodies by using three methods based on different technologies. A cross-sectional study was performed in 50 patients with rheumatoid arthritis (RA) treated with adalimumab. Anti-adalimumab antibodies were detected in patients' sera by different techniques: bridging ELISA, reporter gene assay (RGA), and surface plasmon resonance (SPR). Results showed that all methods recognized anti-adalimumab antibodies and the percentage of positives fluctuated among the assays. Five (10%) of the 50 patients were positive in ELISA, 4(8%) in RGA, and 6(12%) in SPR. Among positive patients, 4 were positive in the three assays, one patient uniquely in ELISA, and two in SPR. Spearman correlation between ELISA and RGA showed good agreement (Spearman r = 0.800). No correlation between RGA and SPR was observed (Spearman r = 0.108). Similar results were obtained between ELISA and SPR (Spearman r = -0.241). Summarizing, ELISA, RGA and SPR recognized anti-adalimumab antibodies in few RA patients, showing good agreement among the methodology employed. On the other hand, differences observed between SPR and ELISA or RGA highlight the relevance of the employed technologies in anti-drug antibody identification.