Twenty to thirty patients will receive Rexin-G at either Dose Level 1 or 2. Patients will be assigned a dose level based on the estimated tumor burden as measured by PET-CT imaging studies. Estimated tumor burden is measured by multiplying the sum of the longest diameters of target lesions in cm by 10e9 cancer cells. If the tumor burden is less than 10 billion cells, the patient will be assigned to Dose Level 1, if the tumor burden is greater than 10 billion cells, the patient will be assigned to Dose Level 2.