Vedolizumab directly blocks integrin α4ß7 on circulating immune cells preventing their egress from the blood, while etanercept blocks the TNFα signaling necessary for the α4ß7 cognate addressin MAdCAM-1 to be expressed in pancreatic endothelial cells. For these reasons, the investigators hypothesize that the two agents may synergistically prevent diabetogenic immune cells from trafficking from the periphery to their target tissue to cause islet cell destruction. Cells from both the myeloid (e.g., myeloid DC1 cells and non-classical monocytes) and lymphoid compartments (e.g., diabetes antigen-specific T cells) would be impacted by this therapeutic combination.
The underlying hypothesis is that vedolizumab will modify immune cell trafficking in type 1 diabetes, and that this will be enhanced by pre-treatment with etanercept. This study will determine whether there is mechanistic evidence in support of this hypothesis and provide preliminary information about safety, efficacy, and tolerability of vedolizumab with and without pretreatment with etanercept in adults with type 1 diabetes (T1D)