Reactive Immunomodulator Addition to Infliximab Monotherapy Restores Clinical Response in Inflammatory Bowel Disease: A Meta-Analysis.

Background and aims: Patients with inflammatory bowel disease (IBD) receiving infliximab (IFX) commonly experience immunogenic loss of response (LOR) by formation of anti-drug antibodies (ADAs). An immunomodulator (IMM) used in combination with initial IFX induction is known to reduce ADA development and improve clinical outcomes. We aimed to assess the impact of reactively adding an IMM to patients on IFX monotherapy.

Methods: We conducted a retrospective cohort study and systematic review with meta-analysis of patients with IBD demonstrating immunologic LOR, with or without clinical LOR, that had an IMM (azathioprine, 6-mercaptopurine, or methotrexate) reactively added (reactive combination therapy; rCT) to combat elevated ADAs and raise IFX level. Data were extracted for pooled effect size estimation using random-effects models, and ADA and IFX trough levels were compared pre- and post-IMM initiation.

Results: We identified 6 patients who received rCT due to rising ADA titers and low IFX levels. Median ADA titer decreased from 506 ng/mL (interquartile range (IQR) [416-750]) to 76.5 ng/mL (IQR [25.8-232]), an 85% decrease (p = 0.031). Median IFX trough increased from 0.4 µg/mL (IQR [0.4-0.48]) to 8.25 µg/mL (IQR [3.7-9.6]), a 20.6-fold increase (p = 0.038). Meta-analysis pooled effect size of 7 studies with 89 patients showed an 87% ADA titer reduction [95% confidence interval (CI) = 72-94%], 6.7-fold increased IFX trough (95% CI = 2.4-18.7), and 76% clinical remission rescue rate (95% CI = 59-93%).

Conclusions: These results suggest rCT is a valid rescue strategy in patients with immunogenic LOR to IFX to reduce ADA titers, restore therapeutic IFX levels, and recapture clinical remission of IBD.