IMPORTANCE There are conflicting data on the association of antidrug antibodies with response tobiologic disease–modifying antirheumatic drugs (bDMARDs) in rheumatoid arthritis (RA).OBJECTIVE To analyze the association of antidrug antibodies with response to treatment for RA.DESIGN, SETTING, AND PARTICIPANTS This cohort study analyzed data from the ABI-RA (Anti-Biopharmaceutical Immunization: Prediction and Analysis of Clinical Relevance to Minimize the Riskof Immunization in Rheumatoid Arthritis Patients) multicentric, open, prospective study of patientswith RA from 27 recruiting centers in 4 European countries (France, Italy, the Netherlands, and theUK). Eligible patients were 18 years or older, had RA diagnosis, and were initiating a new bDMARD.Recruitment spanned from March 3, 2014, to June 21, 2016. The study was completed in June 2018,and data were analyzed in June 2022.EXPOSURES Patients were treated with a new bDMARD: adalimumab, infliximab (grouped as anti–tumor necrosis factor [TNF] monoclonal antibodies [mAbs]), etanercept, tocilizumab, and rituximabaccording to the choice of the treating physician.MAIN OUTCOMES AND MEASURES The primary outcome was the association of antidrug antibodypositivity with EULAR (European Alliance of Associations for Rheumatology; formerly, EuropeanLeague Against Rheumatism) response to treatment at month 12 assessed through univariate logisticregression. The secondary end points were the EULAR response at month 6 and at visits from month6 to months 15 to 18 using generalized estimating equation models. Detection of antidrug antibodyserum levels was performed at months 1, 3, 6, 12, and 15 to 18 using electrochemiluminescence (MesoScale Discovery) and drug concentration for anti-TNF mAbs, and etanercept in the serum wasmeasured using enzyme-linked immunosorbent assay.RESULTS Of the 254 patients recruited, 230 (mean [SD] age, 54.3 [13.7] years; 177 females [77.0%])were analyzed. At month 12, antidrug antibody positivity was 38.2% in patients who were treatedwith anti-TNF mAbs, 6.1% with etanercept, 50.0% with rituximab, and 20.0% with tocilizumab.There was an inverse association between antidrug antibody positivity (odds ratio [OR], 0.19; 95% CI,0.09-0.38; P all the visits starting at month 6 using generalized estimating equation models confirmed the inverseassociation between antidrug antibody positivity and EULAR response (OR, 0.35; 95% CI, 0.18-0.65;P P = .03). In the multivariable analysis, antidrug antibodies, body mass index, and rheumatoid factorwere independently inversely associated with response to treatment. There was a significantly higher drug concentration of anti-TNF mAbs in patients with antidrug antibody–negative vs antidrugantibody–positive status (mean difference, −9.6 [95% CI, −12.4 to −6.9] mg/L; P concentrations of etanercept (mean difference, 0.70 [95% CI, 0.2-1.2] mg/L; P = .005) andadalimumab (mean difference, 1.8 [95% CI, 0.4-3.2] mg/L; P = .01) were lower in nonresponders vsresponders. Methotrexate comedication at baseline was inversely associated with antidrugantibodies (OR, 0.50; 95% CI, 0.25-1.00; P = .05).CONCLUSIONS AND RELEVANCE Results of this prospective cohort study suggest an associationbetween antidrug antibodies and nonresponse to bDMARDs in patients with RA. Monitoring antidrugantibodies could be considered in the treatment of these patients, particularly nonresponders tobiologic RA drugs.Pathophysiology and treatment of rheumatic disease
