Balsa A, et al. - The bi-fold aim of this trial was to examine the prevalence of anti-drug antibodies (ADA) in patients with rheumatoid arthritis (RA) or SpA experiencing secondary failure to anti-tumour necrosis factor (anti-TNF) therapy and to associate the ADA presence with anti-TNF concentration and clinical response. Excluding etanercept (ETN), the development of ADA against adalimumab (ADL) or infliximab (INF) served as one of the primary reasons for secondary treatment failure but not the only one, in patients with RA or SpA and secondary failure.

Methods

• The scheme of this trial was a cross-sectional, observational study.
• Eligible candidates included patients with active RA or SpA experiencing secondary failure to etanercept (ETN), infliximab (INF) or adalimumab (ADL).
• During this study, concomitant non-biologic DMARDs were permitted.
• Researchers computed serum anti-TNF and ADA levels, with the aid of the two-site ELISA.

Results

• Individuals with RA (n = 276) were mostly female (80 vs 39%), older (56 vs 48 years), received concomitant DMARDs (83 vs 47%) and had maintained good clinical disease control for longer (202 vs 170 weeks) compared to patients with SpA (n = 294), among 570 evaluable patients.
• Data illustrated the presence of ADA in 114/570 (20.0%) patients; 51/188 (27.1%) against INF and 63/217 (29.0%) against ADL; none against ETN.
• Among these 114 patients, 92 (81%) enrollees did not report any detectable serum drug concentrations.
• The presence of anti-INF antibodies was detected in proportionately more patients with SpA (31.3%) than those with RA (21.1%; P=0.014).
• The development of ADA was disclosed in a substantially lower proportion of patients receiving concomitant DMARDs (16.5%) when compared to those on monotherapy (26.4%; P < 0.05).