The purpose of this phase II study is to evaluate an investigational monoclonal antibody for the treatment of glucocorticoid-refractory Graft Versus Host Disease (GVHD). Patients diagnosed with GVHD who have not responded satisfactorily to, or are intolerant of, treatment with standard agents will be considered for entry. Patients will be allowed to continue on their other immunosuppressive drugs at stable doses during the trial. The research is being conducted at up to 20 clinical research sites in the US.

• Grade II to IV GVHD
• Clinical findings: skin thickening, joint contraction, oral ulceration, diarrhea.
• History of allogeneic hematopoietic cell transplant (HCT).
• Patients must have failed to respond or clearly progress to previous therapy on or before day +100 posttransplant.
• Patients must have adequate renal, hepatic, cardiac function and hematologic values