Focus of the Report: This Health Technology Assessment focuses on anti-infliximab (IFX) antibody (ATI) testing in patients who are undergoing IFX treatment for Crohn disease (CD). This testing is a type of therapeutic drug monitoring (TDM) that is performed to help determine whether ongoing treatment is safe and effective and whether changes are needed.
Technology Description: ATI levels are usually measured with an enzyme-linked immunosorbent assay (ELISA), which involves capturing the antibodies in wells of plastic dishes that are coated with IFX and using a chemical reaction to determine the level of ATI present. In patients who are undergoing treatment with IFX, detecting ATI with a conventional enzyme-linked immunoassay is often not possible because of interference by the IFX in the blood sample. This interference can be overcome, but it requires specialized sample processing or a more complex assay technique.
Controversy: Although ATI formation can block the therapeutic effect of IFX, ATI testing may not improve patient management relative to strategies based on monitoring patient symptoms, biochemical markers, such as C-reactive protein levels and fecal calprotectin, and/or circulating levels of IFX.
How accurate are tests for ATI as part of TDM for detecting and predicting loss of response to IFX in patients with CD?
Does monitoring of ATI levels improve management of patients who have CD?
What safety issues are associated with TDM using ATI?
Have definitive patient selection criteria been established for TDM using ATI in patients with CD?
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