ysabri is a humanized monoclonal antibody that belongs to a class of potential therapeutics known as alpha-4 integrin inhibitors. Tysabri binds to the cell surface receptors known as alpha-4-beta-1 (VLA-4) and alpha-4-beta-7. The receptors for the a4 family of integrins include vascular cell adhesion molecule-1 (VCAM-1), which is expressed on activated vascular endothelium, and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) present on vascular endothelial cells of the gastrointestinal tract. It is designed to block immune cell adhesion to blood vessel walls; it thus blocks subsequent migration of lymphocytes into tissue.
Tysabri is specifically indicated for inducing and maintaining clinical response and remission in adult patients with moderately to severely active Crohn?s disease with evidence of inflammation who have had an inadequate response to, or are unable to tolerate, conventional CD therapies and inhibitors of TNF-a.
Tysabri is supplied as a 300 mg vial designed for intravenous infusion. This concentrated solution that must be diluted prior to intravenous infusion. The recommended initial dose of the drug is a 300 mg intravenous infusion over one hour every four weeks. Tysabri should not be used with concomitant immunosuppressants or concomitant inhibitors of TNF-a. If the patient with Crohn?s disease has not experienced therapeutic benefit by 12 weeks of induction therapy, discontinue treatment.