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Formation of antibodies against infliximab and adalimumab strongly correlates with functional drug levels and clinical responses in rheumatoid arthritis
  1. T R D J Radstake1,
  2. M Svenson2,
  3. A M Eijsbouts3,
  4. F H J van den Hoogen3,
  5. C Enevold2,
  6. P L C M van Riel1,
  7. K Bendtzen2
  1. 1
    Department of Rheumatology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
  2. 2
    Institute for Inflammation Research (IIR), Rigshospitalet National University Hospital Copenhagen, Denmark, and BioMonitor A/S, Symbion Science Park, Copenhagen, Denmark
  3. 3
    Department of Rheumatology, St Maartenskliniek, Nijmegen, The Netherlands
  1. Correspondence to Dr T R D J Radstake, Department of Rheumatology, Radboud University Nijmegen Medical Centre, Geert Grooteplein 8, 6500 HB Nijmegen, The Netherlands; T.Radstake{at}


Background: Tumour necrosis factor α (TNFα) neutralising antibody constructs are increasingly being used to treat rheumatoid arthritis (RA).

Objective: To determine potential differences in clinical responses, soluble drug levels and antibody formation between patients with RA receiving infliximab and adalimumab.

Methods: 69 patients with RA fulfilling the 1987 American College of Rheumatology criteria and about to start treatment with infliximab or adalimumab, were enrolled consecutively. All patients had active disease (28-joint count Disease Activity Score >3.2). Infliximab was given intravenously at 3 mg/kg at baseline and after 2, 6 and 14 weeks. Adalimumab was administered as 40 mg biweekly subcutaneously. Concomitant drug treatment was monitored and continued at constant dosage during the study. All serum samples were tested for infliximab/adalimumab levels and anti-infliximab/anti-adalimumab antibodies.

Results: 35 patients received infliximab, 34 received adalimumab. At 6 months, 15 (43%), 6 (17%) and 14 (40%) of the infliximab-treated patients fulfilled the EULAR criteria for good, moderate and non-responders, respectively, whereas the corresponding figures for adalimumab-treated patients were 16 (47%), 8 (24%) and 10 (29%). Clinical responses correlated with the levels of S-infliximab/adalimumab and the formation of anti-infliximab/anti-adalimumab antibodies.

Conclusion: The clinical response to two anti-TNFα biological agents closely follows the trough drug levels and the presence of antibodies directed against the drugs. Further studies that focus on the underlying pathways leading to antibody formation are warranted to predict immunogenicity of these expensive biological agents and treatment outcomes.

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  • Funding The study was partly funded by Abbott Immunology Inc, Chicago, USA.

  • Competing interests None.

  • Ethics approval Approval from the local ethics committee.

  • Abbott Inc did not have any influence on the set-up of the study, the interpretation of the data or the writing of the paper.