Understanding the Relationship Between Infliximab Levels to Clinical Response of Remicade in Crohn's Disease

The efficacy of infliximab to maintain remission in Crohn's disease has been confirmed by
randomized, controlled trials, however the utility of serum infliximab and ATI titers is
less clearly described in the clinical practice setting to manage dose and interval levels.

The primary objective of this study is to evaluate the clinical responsiveness of active
(HBI >10) Crohn's disease to infliximab as it relates to serum infliximab levels. Though
the assay for an infliximab level is commercially available, current dosing practices rely
on the assessment of clinical data (laboratory data, symptoms, colonoscopy, etc). In order
to understand this relationship, serum infliximab and ATI titers will be collected over the
course of 8 (approximately 1 year) infusions. The results of these levels will be
retrospectively correlated to the patient's clinical response to treatment.

The secondary objective is to identify predictors of poor response to infliximab by
evaluating the efficacy of a dose escalation strategy in patients classified as primary or
secondary non-responders.

Understanding the association of serum infliximab levels to disease response may be a useful
objective tool to optimize and individualize dosing amount and frequency especially in
patients with incomplete or loss of response to therapy.

Inclusion Criteria:

- Patients with active (HBI >10) refractory inflammatory and/or perianal fistulizing
Crohn's disease who are prescribed infliximab as standard of care by their
gastroenterologist.

Exclusion Criteria:

- Pregnant women.

- Patients with a prior history of receiving infliximab.