Abstract:

Objective It is not clear that some patients with crohn′s disease do not respond to treatmentwith anti⁃umor necrosis factor（anti⁃TNF）agents，such as infliximab. We investigated whether loss of anti⁃TNFagents through intestinal mucosa reduces the efficacy of infliximab in patients with CD. Methods We collectedfecal samples from 32 consecutive patients with moderate to severely active CD during the first 2 weeks of infliximabtherapy. Infliximab concentrations were measured in serum and supernatants of fecal samples using an ELISA. Clinicaland endoscopic responses were assessed 2 and 8 weeks and 3 months after treatment began. Results Infliximabwas detected in 135 of 179 fecal samples（75.4%）. The highest concentrations were measured in the first days afterthe first infusion. Patients that were clinical non⁃responses at week 2 had significantly higher fecal concentrationsof infliximab after the first day of treatment than patients with clinical responses（median concentration，7.01 ±0.71 mg/mL in nonresponders vs. 1.04 ± 0.58 mg/mL in responders，P = 0.031）. We did not observe a correlationbetween fecal and serum concentrations of infliximab. Conclusions Infliximab is lost into stools of patientswith CD. High fecal concentrations of infliximab in the first days after therapy begins are associated with primarynonresponse.

Key words: infliximab, lack of response, crohn′s disease, mucosal injury