In the phase II portion of the study, subjects will be randomized between sorafenib, 400 mg, by mouth (PO), twice a day (the approved dose and schedule) versus sorafenib with PR104 at the dose determined in the phase I portion of the study. PR104 will be administered every 4 weeks (one cycle). Subjects will be evaluated each week during cycle 1 and every two weeks thereafter. A disease assessment will be performed after every two cycles. Subjects with progression will be removed from study. Subjects with a response or stable disease may continue on study if this is considered beneficial by their physician.