Drug Levels Associated with Optimal Discrimination between Remission and Nonremission and Comparison of Antibody Assays during First Year of Stable Infliximab Maintenance Therapy in Inflammatory Bowel Disease
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Background:To implement therapeutic drug monitoring-based strategies for infliximab (IFX) in inflammatory bowel disease, the authors assessed IFX levels for optimal discrimination between remission and nonremission and compared assays for anti-IFX antibodies (Abs).Methods:The retrospective cohort comprised 163 bionaive patients with inflammatory bowel disease who received stable IFX maintenance therapy (5 mg/kg every 8 weeks [q8w]) for 1 year. The clinical and biochemical remission status was assessed at all infusions (weeks 14-22-30-38-46-54), and IFX and anti-IFX Abs were estimated using a time-resolved fluorometric assay (n = 690; 88% of infusions). Samples positive for anti-IFX Abs or IFX levels < limit of detection (n = 102) were analyzed by 2 binding assays [enzyme-linked immunosorbent assay (ELISA)] and functional reporter gene assay/drug-tolerant enzyme immunoassay.Results:At all assessed time points, IFX levels were more than double in patients presenting clinical or biochemical remission. An IFX concentration of 4.5 mcg/mL was associated with clinical remission during the entire first year of therapy [sensitivity 54% (49-59), specificity 73% (67-78), AUCROC0.65 (0.60-0.69), P < 0.0001]; these values were comparable with biochemical remission. Exploratory assessments for endoscopic remission (n = 131) were performed at the discretion of the treating physician. Anti-IFX Abs were associated with undetectable IFX and treatment failure [OR 2.9 (1.4-6.0), P < 0.01], irrespective of persistency or transiency. All performed assays detected anti-IFX Abs were picked up by all assays in ∼2/3 of samples. Binding assays demonstrated a higher sensitivity to anti-IFX Abs.Conclusions:IFX at ∼5 mcg/mL was associated with clinical and biochemical remission during the first year of maintenance therapy. During this phase of therapy, standard binding assays are appropriate for therapeutic drug monitoring.
Original language | English |
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Journal | Therapeutic Drug Monitoring |
Volume | 44 |
Issue number | 2 |
Pages (from-to) | 290-300 |
Number of pages | 11 |
ISSN | 0163-4356 |
DOIs | |
Publication status | Published - 2022 |
Bibliographical note
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© 2022 Lippincott Williams and Wilkins. All rights reserved.
- antibodies, antidrug antibodies, inflammatory bowel disease, infliximab, therapeutic drug monitoring, therapeutic thresholds
Research areas
ID: 345020891