Therapeutic Drug Monitoring of Infliximab in Jordanian Patients

Background: Infliximab is a critical biologic therapy for severe inflammatory diseases, but its efficacy can be compromised by the development of anti-drug antibodies (ADAs). Therapeutic drug monitoring (TDM) is a recommended strategy to optimize treatment, but its implementation in Jordan has been limited. This study is the first to evaluate infliximab TDM in a Jordanian patient cohort.Methods: Seventy-three Jordanian patients with inflammatory bowel disease (IBD) were recruited for this study. Trough levels of infliximab and ADAs were measured using enzyme-linked immunosorbent assay (ELISA). Clinical and demographic data, including Erythrocyte Sedimentation Rate (ESR) and smoking status, were collected and analyzed.Results: A significant negative correlation was observed between infliximab trough levels and ADA levels (r = -0.69, p < 0.001). A notable 33.8% of patients developed high ADA titers (>100 ng/mL). ESR and smoking were significantly associated with lower infliximab levels and higher ADA levels. Other factors, such as hormones (Free T4, TSH), vitamins, and kidney and liver function tests, did not show significant correlations.Conclusion: This study provides the first evidence from Jordan supporting the utility of TDM for infliximab. The high prevalence of ADAs and their correlation with negative clinical outcomes underscore the need for routine TDM to guide dosing strategies and improve patient outcomes in Jordan. The findings also highlight ESR and smoking as potential risk factors for treatment failure.