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.

Key Questions:

  • 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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