 The purpose of this research study is to determine the effectiveness of bortezomib Velcade plus prednisone for treating chronic graft versus host disease cGVHD and the safety of this drug combination in this patient population. Chronic GVHD is a medical condition that may occur after allogeneic stem cell transplantation. The donors immune system may recognize the participants body the host as foreign and attempt to reject it. Bortezomib has been used in other research studies, and information from those studies suggests that this drug may help to control the abnormal immune responses that underlie cGVHD. 