Early drug and anti-infliximab antibody levels for prediction of primary nonresponse to infliximab therapy

H. Bar-Yoseph, N. Levhar, L. Selinger, U. Manor, M. Yavzori, O. Picard, E. Fudim, U. Kopylov, R. Eliakim, S. Ben-Horin, Y. Chowers, B. Ungar*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Background: Primary nonresponse, defined as lack of clinical benefit during the induction phase, occurs in up to 30% of IBD patients treated with infliximab. The mechanisms underlying primary nonresponse have not yet been clearly defined. Aim: To evaluate the association of early (week 2 and week 6) induction infliximab and anti-infliximab antibody levels with primary nonresponse. Methods: A retrospective observational case-control study of inflammatory bowel disease patients treated with infliximab and followed at Sheba Medical Center between 2009 and 2016 was performed. Pre-infusion infliximab and antibodies to infliximab (ATI) levels were measured by our previously described drug-tolerant ELISA assay. Results: Thirty-five primary nonresponders have been identified and matched with 105 primary responders (1:3 ratios). Both week 2 and week 6 infliximab levels were significantly lower among primary nonresponders compared to responders (week 2, 6: median level 7.2, 2.2 μg/mL vs 13.5, 9.5 μg/mL, P =.0019, P <.0001 respectively). Antibodies to infliximab appeared more frequently (either week 2 or 6, 68% vs 28% prevalence, P =.0004) and at higher levels in nonresponders compared to responders (week 2, 6: median ATI 7.3, 10.8 μg/mL-eq vs 3.8, 4.4 μg/mL-eq, P =.005, P =.008 respectively). Moreover, week 2 infliximab levels <6.8 μg/mL (AUC = 0.68, P =.002, sensitivity 50%, specificity 86%) and antibodies to infliximab levels >4.3 μg/mL-eq (AUC = 0.78, P =.0004, sensitivity 77%, specificity 71%) were predictive of primary nonresponse. Among the other clinical and demographic variables, higher baseline ulcerative colitis clinical score, infliximab monotherapy, prior adalimumab therapy and previous Crohn's disease-related surgeries were also associated with an increased risk of primary nonresponse. Conclusions: Infliximab levels below 6.8 μg/mL and antibodies to infliximab levels above 4.3 μg/mL-eq before the second infusion are associated with primary nonresponse, especially among Crohn's disease patients.

Original languageEnglish
Pages (from-to)212-218
Number of pages7
JournalAlimentary Pharmacology and Therapeutics
Issue number2
StatePublished - Jan 2018


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