Active or suspected drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements Judged by the investigator to be at significant risk of failing to comply with the provisions of the protocol as to cause harm to self or seriously interfere with the validity of the study results Active or acute Centers for Disease Control Clinical Category C event at screening. (Note: Treatment for the acute event must have been completed at least 28 days prior to screening.) Clinically relevant pancreatitis or clinically relevant hepatitis at screening Hgb<8g/dl, platelet count <50,000/mm3, calculated creatinine clearance <50ml/min via Cockroft-Gault equation, or AST or ALT > 5X the ULN Any Grade 4 laboratory abnormality