In a retrospective study, we found significant association between serum levels of anti-tumor necrosis factor agents and level of mucosal healing. We propose that serum levels of 6-10 μg/mL for infliximab and 8-12 μg/mL for adalimumab are required to achieve mucosal healing in 80%-90% of patients with IBD, and that this could be considered as a "therapeutic window." Exceeding these levels produces only a negligible gain in proportion of patients with mucosal healing.

When followed prospectively, most patients who develop ATI do so within the first 12 months of therapy. This incidence is reduced by concomitant immunomodulator even in scheduled-therapy patients. In contrast, transient ATI, which are of little clinical significance, can appear haphazardly at any time during treatment. The onset of clinical loss of response may lag behind the appearance of anti-infliximab antibodies.

No abstract

F(ab')(2) is the immunogenic fragment of infliximab. However, ATI level in serum--combined with measurement of trough infliximab level--is better correlated with the clinical response to infliximab or with its loss.

No abstract

Anti-Remicade antibodies in patients with IBD recognise and functionally inhibit Remsima to a similar degree, suggesting similar immunogenicity and shared immunodominant epitopes on these two infliximab agents. In contrast, anti-adalimumab antibodies do not cross-react with Remsima or Remicade.

No abstract

High IFX trough levels during induction are associated with favorable fistula response to anti-TNF treatment. If validated in a larger prospective study, our findings may help guide anti-TNF treatment in patients with perianal CD, and suggest serum level-guided treatment escalation in non-responders or prompt changing of biologic treatment in non-responders.