CPT® Code 80280

The CPT® Code 80280 refers to a laboratory test specifically designed to monitor therapeutic drug levels of vedolizumab (VDZ). Vedolizumab is a recombinant humanized immunoglobulin G1 (IgG1) monoclonal antibody that plays a crucial role in the treatment of inflammatory bowel diseases, including Crohn's disease and ulcerative colitis. The mechanism of action for VDZ involves its binding to the a4b7 integrin glycoprotein found on the surface of T and B lymphocytes. This binding action effectively prevents these immune cells from migrating through the vascular endothelium into the intestinal mucosa, thereby exerting an anti-inflammatory effect. Monitoring the levels of VDZ is essential, as therapeutic activity may be compromised in a significant portion of patients. Specifically, 10-30% of patients may experience inadequate dosing during the induction phase of treatment, leading to what is termed primary non-response. Additionally, about 50% of patients who initially respond to therapy may later exhibit a lack of sustained clinical improvement, known as secondary non-response. Both primary and secondary non-responses have been associated with low serum trough concentrations of VDZ. Factors contributing to low drug levels can include low serum albumin levels, elevated body weight, and the development of antibodies against VDZ. To perform this test, a blood sample is collected, which is a separate procedure from the testing itself. The serum obtained from the blood sample is then analyzed for quantitative levels of VDZ and the presence of anti-VDZ antibodies using an enzyme-linked immunosorbent assay (ELISA), providing critical information for the management of patients undergoing treatment with this medication.