A humanized monoclonal antibody targeting the β7 integrin selectively blocks intestinal homing of T lymphocytes

BACKGROUND AND PURPOSE rhuMAb Beta7 is a humanized anti-human beta 7 monoclonal antibody currently in phase I in inflammatory bowel disease. rhuMAb Beta7 binds the beta 7 subunit of the integrins alpha 4 beta 7 and alpha E beta 7, blocking interaction with their ligands. These integrins play key roles in immune cell homing to and retention in mucosal sites, and are associated with chronic inflammatory diseases of the gastrointestinal tract. The goal of this study was to evaluate the mucosal specificity of rhuMAb Beta7. EXPERIMENTAL APPROACH We assessed the effect of murine anti-Beta7 on lymphocyte homing in mouse models of autoimmune disease. We also compared the effect of rhuMAb Beta7 on circulating mucosal-homing versus peripheral-homing T cells in nave non-human primates. KEY RESULTS In cynomolgus monkeys, occupancy of beta 7 integrin receptors by rhuMAb Beta7 correlated with an increase in circulating beta(7+) mucosal-homing lymphocytes, with no apparent effect on levels of circulating beta 7-peripheral-homing lymphocytes. rhuMAb Beta7 also inhibited lymphocyte homing to the inflamed colons of severe combined immunodeficient mice in CD45RB(high) CD4+ T-cell transfer models. Consistent with a lack of effect on peripheral homing, in a mouse model of experimental autoimmune encephalomyelitis, anti-beta 7 treatment resulted in no amelioration of CNS inflammation. CONCLUSIONS AND IMPLICATIONS The results presented here suggest that rhuMAb Beta7 selectively blocks lymphocyte homing to the gastrointestinal tract without affecting lymphocyte trafficking to non-mucosal tissues. rhuMAb Beta7 provides a targeted therapeutic approach with the potential for a more attractive benefit : risk ratio than currently available inflammatory bowel disease therapies.