Early infliximab antibody testing does not prevent infusion reactions when reinitiating infliximab

Infliximab drug level checking has started to revolutionize the treatment of inflammatory bowel disease, allowing for more accurate dosing. Recently, Brandse and colleagues and Gagniere and colleagues both noted the potential benefit of a re-introduction of infliximab after prior failure in patients with Crohn’s disease. Unfortunately though, approximately 1/3 of patients stopped the drug due to side effects of the attempted retreatment from infusion reactions. In their study, they also noted that concomitant usage of a thiopurine did not provide any additional benefit. Presumably, majority of these reactions are secondary to antibody formation to infliximab. In order to reduce the risk of infusion reactions, we present a case of a patient with Crohn’s disease who was retried on infliximab and had antibody testing after the first dose to assess if it would be safe to continue the drug, as most infusion reactions occur at the second dose.