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Decreased clinical response to infliximab in ankylosing spondylitis is correlated with anti-infliximab formation
  1. Mirjam K de Vries1,
  2. Gerrit Jan Wolbink2,
  3. Steven O Stapel2,
  4. Henk de Vrieze2,
  5. J Christiaan van Denderen3,
  6. Ben A C Dijkmans1,
  7. Lucien A Aarden2,
  8. Irene E van der Horst-Bruinsma1
  1. 1VU University Medical Center, Amsterdam, the Netherlands
  2. 2Sanquin Research, Amsterdam, the Netherlands
  3. 3Jan van Breemen Institute, Amsterdam, the Netherlands
  1. Correspondence to:
    Mirjam K de Vries
    MD, VU University Medical Centre, Rheumatology department, room 4A-42, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands; mk.devries{at}


Objectives: Correlation of serum trough infliximab levels and antibodies to infliximab (anti-infliximab) with clinical response in ankylosing spondylitis.

Methods: In accordance with the international ASsessment in Ankylosing Spondylitis (ASAS) consensus statement, patients were treated with infliximab (5 mg/kg) every 6 weeks after a starting regimen. Preinfusion sera were collected at baseline, 24 and 54 weeks. At every visit, the 20% improvement response (ASAS-20) was assessed and laboratory tests performed.

Results: 24 of the 38 (63%) patients fulfilled ASAS-20 response criteria after 24 weeks of treatment and 21 (53%) after 54 weeks. After 54 weeks, 11 (29%) patients showed undetectable serum trough infliximab levels and detectable anti-infliximab; six of these patients developed an infusion reaction. Anti-infliximab was found significantly more often (p = 0.04) in ASAS-20 non-responders compared with responders at week 54. Serum trough infliximab levels were significantly (p<0.0001) lower in patients with (mean 0.02 mg/l) than in those without (12.7 mg/l) anti-infliximab.

Conclusions: In ankylosing spondylitis, high levels of serum trough infliximab correlated with a good clinical response. Detection of anti-infliximab within 54 weeks is associated with undetectable serum trough infliximab levels, reduced response to treatment and increased risk of developing an infusion reaction.

  • AU, arbitrary unit
  • ASAS, ASsessment in Ankylosing Spondylitis
  • BASDAI, Bath Ankylosing Spondylitis Disease Activity Index
  • HLA, human leucocyte antigen
  • Spondylitis
  • ankylosing
  • tumor necrosis factor-alpha
  • infliximab
  • antibodies to infliximab

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  • Published Online First 27 April 2007