Therapeutic drug monitoring of adalimumab for dose optimization during maintenance therapy in patients with ulcerative colitis: real-world data

Introduction : Ulcerative colitis (UC) is a chronic inflammatory disease that primarily affects the colon. Tumor necrosis factor-α inhibitors (like adalimumab) are effective agents for UC. However, loss of response may occur. Proactive therapeutic drug monitoring involves measuring drug levels at regular intervals in patients in remission to maintain therapeutic concentrations and potentially prevent loss of response. Aim : This study aims to evaluate adalimumab trough level (TL), the development of anti-drug antibodies (ADAs), and their relationships with clinical and laboratory variables in Iraqi patients with ulcerative colitis receiving adalimumab therapy. Patients and methods : The present study was cross-sectional and conducted from April 2024 to November 2024. It included 44 UC patients allocated into 2 groups: group 1 (patients with TL within or above the therapeutic range) and group 2 (patients with TL below the therapeutic range). Results : Out of 44 patients, 23 patients reached target TL, while 21 patients did not. Based on the TL, developments of ADAs, and clinical state of patients, recommendations were made to escalate the dose for 13 patients, switch therapy for 16 patients, de-escalate the dose for 10 patients, and continue therapy for 5 patients. Additionally, it was found that neutrophil count, erythrocyte sedimentation rate, and C-reactive protein were higher, and hemoglobin and packed cell volume were lower in patients who did not reach the target adalimumab TL ( p <0.05). Conclusions : Therapeutic drug monitoring for adalimumab can be an important tool for optimizing UC treatment and explaining the potential causes of non-responsiveness to this medicine.