Rationale for Incorporating Vedolizumab to Maintenance post Autologous Transplantation: While the results of the ASTIC trial suggest autologous BMT for CD is an effective therapy, there is still room for improvement as sustained remission is achieved in only 44% of patients. The reasons for the failure of induction of remission and the lack of sustained response in a portion of patients are unknown, but presumably recapitulation of the autoimmune response after transplant plays an important role. Vedolizumab is appealing to test after autologous stem cell transplant as it targets inflammatory T cells destined for the intestine (expressing α4β7). These T cells would be expected to be present in the graft and their blockade may improve the induction of remission achieved by the graft and leave the majority of protective T cells in the graft available to the recipient's recovering immune system. The addition of vedolizumab not only has the potential to improve induction of remission from the transplant itself but, as an adjunct therapy post-transplant, it may also help to maintain remission in this patient cohort. The need to provide patients with maintenance therapy post inductive therapy is well established both for medical therapeutics as well as post-operatively and vedolizumab has been established as an effective maintenance agent. The restoration of response to previously failed medications observed in other studies suggests that patients who did not respond to vedolizumab previously may now respond post HCT. This study will test the hypothesis that vedolizumab maintenance therapy will improve outcomes at 1 year post-transplant by decreasing the portion of patients whose disease recurs and increasing the portion of patients for whom the transplant induces remission.