Infliximab trough levels and persistent vs transient antibodies measured early after induction predict long-term clinical remission in patients with inflammatory bowel disease

Abstract Background The use of therapeutic drug monitoring has been proposed as a useful tool in the management of patients with loss of response to biological therapy in patients with inflammatory bowel disease. Aims To evaluate whether early, post-induction anti-tumor necrosis factor trough levels and the presence of different types of anti-drug antibodies may impact long-term clinical remission in patients with inflammatory bowel disease. Methods We prospectively assessed anti-tumor necrosis factor trough levels and both persistent and transient anti-drug antibodies. The Harvey–Bradshaw Index and the partial Mayo score were evaluated at each visit or in case of relapse. Results At week 14, median infliximab trough levels were significantly lower in patients who experienced loss of response at week 48 as compared to patients in stable remission (1.3 mcg/mL [range 0–10.2 mcg/mL] vs . 10.1 mcg/mL[range 0–42.8 mcg/mL], P   0.0004). ROC curve identified an infliximab trough levels of 6.2 mcg/mL as the cut-off value with the highest accuracy ( c -index = 0.864) for loss of response at week 48. At week 14 we observed a correlation between anti-drug antibodies concentration and infliximab trough levels ( r s  = −0.513, P  = 0.04). Conclusions The results highlight the usefulness of assessing early biological TL in order to predict patients’ long-term outcome.