Gonczi L, et al. – The physicians assessed the frequency and predictive factors of loss of response (LOR) to adalimumab using therapeutic drug monitoring (TDM) in inflammatory bowel disease (IBD) patients. During adalimumab therapy, anti–drug antibodies (ADA) development, low trough levels (TL) and the need for dose intensification were frequent and supported the selective use of TDM in IBD patients treated with adalimumab. Predictors of LOR were ADA positivity and gender.

• The physicians enrolled 112 IBD patients (with 214 TDM measurements, CD/UC 84/28, male/female 50/62, mean age CD/UC: 36/35 years) in this consecutive cohort from two referral centres in Hungary.
• They comprehensively collected demographic data and applied harmonized monitoring strategy.
• They recorded previous and current therapy, laboratory data and clinical activity at the time of TDM.
• They evaluated patients either at the time of suspected LOR or during follow-up.
• They determined TDM measurements by commercial ELISA (LISA TRACKER, Theradiag, France).

• LOR/drug persistence was 25.9%/74.1% among 112 IBD patients.
• After 1 year, the cumulative ADA positivity (>10 ng/mL) and low TL (<5.0 μg/mL) was 12.1% and 17.8% and 17.3% and 29.5% after 2 years of adalimumab therapy.
• In this study, dose intensification was required in 29.5% of the patientss.
• Factors associated with LOR were female gender and ADA positivity (female gender: p < 0.001, OR:7.8 CI 95%: 2.5-24.3, ADA positivity: p = 0.007 OR:3.6 CI 95%: 1.4-9.5).