Group 1: Up to 120 eligible patients will be randomized to receive VAL-083 at 40 mg/m2 IV on days 1, 2, and 3 of a 21-day treatment-cycle, for up to 12, 21-day treatment cycles or until they fulfill one of the criteria for study discontinuation (death, intolerable toxicities, investigator's judgment, or withdrawal of consent). In patients who demonstrate response, stable disease or who continue therapy at the discretion of the investigator following initial progression and tolerate therapy, permission to continue treatment beyond 12 cycles will be considered but will require consent of the Sponsor. VAL-083 will be administered as an IV infusion over 30-60 minutes.