A Dose-Finding Study of Vedolizumab for Treatment of Steroid-Refractory Acute Intestinal Graft-Versus-Host Disease (GvHD) in Participants Who Have Undergone Allogeneic Hematopoietic Stem Cell Transplantation (Allo-HSCT)

The purpose of this study is to assess the initial activity, tolerability, safety and to identify a recommended dose and regimen of vedolizumab intravenous (IV) administered for treatment of steroid-refractory acute intestinal GvHD in participants who have undergone allo-HSCT.

The drug being tested in this study is called vedolizumab. This study will look at the tolerability and effectiveness of vedolizumab IV in participants with acute intestinal GvHD who have received no systemic therapy for the treatment of acute GvHD (prophylaxis acceptable) other than corticosteroids.

The study enrolled 17 participants. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups:

* Vedolizumab 300 mg
* Vedolizumab 600 mg

All participants will be infused intravenously at the same time each day throughout the study. Vedolizumab IV will be administered on Days 1, 15, 43, 71, and 99. After approximately 10 participants are enrolled at each dose level and have data available from the Day 28 evaluation, safety, tolerability, efficacy, and pharmacokinetic (PK), results will be assessed for each dose level, and the appropriate dose for subsequent participants in the study will be determined.

This multi-center trial will be conducted in multiple countries. The overall time to participate in this study is 32 weeks. Participants will make multiple visits to the clinic after last dose of study drug for a follow-up assessment.

Eligibility Criteria:
Inclusion Criteria:

1. Recipient of 1 allogeneic hematopoietic stem cell transplantation (allo-HSCT) but not more than 1 allo-HSCT.
2. Has primary steroid-refractory graft-versus-host disease (GvHD). Steroid-refractory disease is defined as worsening or no improvement in 5 to 7 days of treatment with methylprednisolone 2 milligram per kilogram (mg/kg) or equivalent or lack of a CR after 14 days of primary treatment with methylprednisolone 2 mg/kg or equivalent. Note that participants who develop intestinal GvHD while receiving systemic therapy for other GvHD are still eligible after 5 to 7 days, even if the intestinal GvHD has not been present for the entire duration. Participants who may have received an increase in their steroid dose treatment (example, increased methylprednisolone from 1 mg/kg to 2 mg/kg) before enrollment will be eligible, provided the participant has met the definition of steroid refractory above. Participants who develop toxicity on corticosteroids or who are otherwise medically unable to be dosed to this level, will also be eligible.
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 3.
4. Evidence of myeloid engraftment defined by absolute neutrophil count greater than or equal to (\>=) 0.5\*109/liter (L) on 3 consecutive days.

Exclusion Criteria:

1. Presence of chronic GvHD at Screening (including acute-chronic overlap syndrome).
2. Relapse of underlying malignant disease after allo-HSCT.
3. Hyperacute GvHD defined as onset of GvHD within the first 15 days following hematopoietic stem cell infusion.
4. Received systemic agents other than corticosteroids for treatment of acute GvHD. GvHD prophylaxis agents (example, calcineurin inhibitors) may be continued.
5. Life expectancy of \<3 weeks.