Anti-infliximab Antibodies with Neutralizing Capacity in Patients with Inflammatory Bowel Disease: Distinct Clinical Implications Revealed by a Novel Assay.
About 60% of infliximab (IFX)-treated patients develop antidrug antibodies (ADA), although their clinical significance remains disputed. The aim of this study was to develop an assay for assessing ADA-neutralizing potential, and clinical significance.



An immune assay was devised in which the inhibition of IFX binding to plated-tumor necrosis factor in the presence of patient sera or controls, was assessed and defined as IFX-tumor necrosis factor binding reduction ratio (ITBR). The assay was compared to a bioassay in which tumor necrosis factor-α-induced interleukin-8 secretion from HT-29 cells was assessed after addition of IFX to ADA-containing sera or control sera.



Both assays detected neutralizing antibodies in 39 of 44 ADA-positive sera. The median ITBR was 3.66 (mean 4.9 ± 3.2) in 29 ADA-positive patients with loss of response (LOR), and 1.3 (mean 1.9 ± 1.3) in 15 patients without LOR (P = 0.001). ADA titers in both groups were similar (median 9.5 and 10.2 μg/mL, respectively P = 0.74). Using an ITBR of 1.65, the sensitivity for LOR detection was 86.2% and the specificity was 66.7%. (positive predictive value 83%; negative predictive value 71.4%; P = 0.001). When early ADA-IFX-sera from IFX-treated patients with or without subsequent LOR were compared, the median ITBRs were 1.1 and 0.57, respectively (P = 0.028).



Detection of neutralizing antibody activity was superior to antibody quantization by enzyme-linked immunosorbent assay with respect to correlation with clinical LOR, and for prediction of subsequent LOR. These findings may assist in optimizing infliximab therapy in patients with inflammatory bowel disease.
*Gastroenterology Department, Rambam Health Care Campus, Haifa, Israel; †Bruce Rappaport School of Medicine, Technion-Israel Institute of Technology, Haifa, Israel; ‡Gastroenterology department, Sheba Medical Center Tel Hashomer, Ramat Gan, Israel; and §Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Roni
R
Weisshof
Bella
B
Ungar
Alexandra
A
Blatt
Aviva
A
Dahan
Sigal
S
Pressman
Matti
M
Waterman
Uri
U
Kopylov
Shomron
S
Ben-Horin
Yehuda
Y
Chowers
D000293:Adolescent; D000328:Adult; D057134:Antibodies, Neutralizing / Q000097:blood*; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D001681:Biological Assay / Q000379:methods*; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019073:HT29 Cells; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000097:blood* / Q000188:drug therapy; D000069285:Infliximab / Q000737:chemistry / Q000276:immunology* / Q000627:therapeutic use; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000494:pharmacology; D055815:Young Adult
D057134:Antibodies, Neutralizing; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab