Background: Adalimumab is an effective treatment in patients with Crohn's disease; as it is a humanized anti-tumour necrosis factor monoclonal antibody, immunogenicity is thought not to be of any significance.
Aim: To assess whether antibodies to adalimumab (ATAs) affect adalimumab treatment outcome in patients with Crohn's disease previously treated with infliximab.
Methods: A retrospective study was performed. Patients with active Crohn's disease and who had lost response or were intolerant to infliximab were treated with adalimumab. Clinical response and side effects were assessed as were serum ATAs and antibodies to infliximab (ATIs).
Results: In total 30 patients [M/F (7/23)], median age 36 years (range 21-73) were treated with adalimumab for 318 days (median range 83-632). Clinical response was 77% (23/30), a dose escalation was necessary in eight (27%) patients and side effects were observed in 47% (14/30). In five patients (17%) ATAs were detected; of these patients, four were nonresponders. The presence of ATAs was related to nonresponse to adalimumab (P = 0.006). ATIs were positive in 57% of patients (17/30) and serum levels were significantly increased in adalimumab nonresponders (P = 0.01).
Conclusion: Immunogenicity plays a role in adalimumab treatment because of the development of ATAs.