Study on the Safety and Effectiveness of VELCADE® in the Treatment of Graft-Versus-Host Disease

Inclusion Criteria: (All criteria must be met) 1. Patients must have undergone an allogeneic HSCT 2. Clinical or histological evidence of AGVHD 3. Has been treated with a minimum of 2mg/kg of methylprednisolone per day or equivalent dose of steroids and either one of the following: 1. Has had a minimum of 3 days of steroids including the day of assignment and has progressive disease. 2. Has had a minimum of 7 days of steroids including the day of assignment and has had no response. 3. AGVHD progresses at anytime when steroids are tapered to less than 2mg/kg/day of methylprednisolone or its equivalent. 4. Performance status ECOG 0-2 5. Patients must be willing to use contraception if they have childbearing potential 6. Able to give informed consent 7. Patients must be \> 18 years of age, with no upper age limit. Exclusion Criteria: (Any one criteria will exclude patient) 1. Performance status of ECOG \>2. 2. \>Grade3 peripheral neuropathy at the time of enrollment 3. Patient has a creatinine clearance (calculated or measured) of \<30mL/min at the time of enrollment. 4. Myocardial infarction within 6 months prior to enrollment or has New York Hospital Association (NYHA) Class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias or electrocardiographic evidence of acute ischemia or active conduction system abnormalities. Prior to study entry , any ECG abnormality at Screening has to be documented by the investigator/co-investigator as not medically relevant. 5. Patient has hypersensitivity to bortezomib, boron or mannitol. 6. Female subject is pregnant or breast-feeding. 7. Patient has received other investigational drug within 14 days prior to enrollment. 8. Serious medical or psychiatric illness likely to interfere with participation in this clinical study or to obtain informed consent.