Therapeutic Drug Monitoring (TDM) of Vedolizumab

Vedolizumab (Entyvio) is a humanized monoclonal antibody against α4β7 integrin and used for the treatment of inflammatory bowel diseases such as ulcerative colitis (UC) and Crohn´s disease (CD). Therapeutic cut-off (minimum serum concentration of Vedolizumab that gives a positive response to treatment) is still not known.

α4β7 integrin is a glycoprotein on the surface of T- and B- cells and plays an important role for the cells passage from the blood across the endothelium to the intestinal mucosa. Treatment with Vedolizumab blocks cell passage and thereby down-regulate inflammation in the intestinal mucosa. During treatment, some patients may develop antibodies to Vedolizumab (anti-drug antibodies or ADA). Data and interpretation of Vedolizumab ADA and its serum levels are still very limited.

Testing Vedolizumab concentration:

The assay is performed using an ELISA assay. The lowest detectable concentration of Vedolizumab in serum is 2 µg/mL.

Testing Vedolizumab anti-drug antibodies (ADA):

The assay is performed using ELISA.  ADA can only be detected if the Vedolizumab concentration in serum is < 2 µg/mL. The lowest detectable concentration of these ADA is 35 ng/mL.