CDP323 is a small-molecule prodrug antagonist of the vascular cell adhesion molecule 1 (VCAM-1) binding to α4-integrins.

Vascular cell adhesion protein 1 also known as vascular cell adhesion molecule 1 (VCAM-1) or cluster of differentiation 106 (CD106) is a protein that in humans is encoded by the VCAM1 gene.

Most of them also express common markers of stromal cells such as desmin, laminin, various subunits of integrins, vascular cell adhesion molecule 1 (VCAM1) and mucosal vascular addressin cell adhesion molecule 1 (MAdCAM1).

The products of the early phase reaction include chemokines and molecules that act on endothelial cells and cause them to express Intercellular adhesion molecule (such as vascular cell adhesion molecule and selectins), which together result in the recruitment and activation of leukocytes from the blood into the site of the allergic reaction.