Ng et al., 2019. “Itolizumab As a Potential Therapeutic for the Prevention and Treatment of Graft Vs Host Disease.” Blood. 134: 5603
Background: CD6 is a co-stimulatory receptor, predominantly expressed on T cells, that binds to activated leukocyte cell adhesion molecule (ALCAM), a ligand expressed on antigen presentation cells and various epithelial and endothelial tissues. The CD6-ALCAM pathway plays an integral role in modulating T cell activation, proliferation, differentiation and trafficking and is central to inflammation. While effector T cell (Teff) are CD6hi and upregulate expression upon activation, regulatory T cells (Treg) remain CD6lo/-, making this an attractive target to modulate Teff activity while preserving Treg activity. Early studies by Soiffer and colleagues demonstrated using T12, an anti-CD6 monoclonal antibody (mAb) that ex-vivo depletion of CD6+ donor cells prior to transplantation decreased the incidence of both acute and chronic GVHD, highlighting the importance of CD6+ cells in GVHD pathogenesis and validating it as a therapeutic target. However, it remains to be shown whether modulating the CD6-ALCAM pathway in vivo can attenuate GVHD. We investigated the use of itolizumab, a humanized anti-CD6 mAb that has demonstrated clinical efficacy in other autoimmune diseases, as both a preventive and therapeutic treatment for GVHD, using a humanized xenograft mouse model.