Three patients will receive the Mx-dnG1 retroviral vector at Dose Level I. If 1 of 3 patients at Dose Level I develops a grade 3 or 4 adverse event (CTC Version 2.0) which appears to be related or possibly related to the Mx-dnG1 retroviral vector, then 3 additional patients will be enrolled at the same dose level. If at least 2 of the first 3, or 3 of 6, patients at Dose Level I develop a grade 3 to 4 adverse event which appears to be related or possibly related to the Mx-dnG1 retroviral vector, accrual into the study will be held until the data are discussed with the Food and Drug Administration (FDA) and a decision is made whether to continue or terminate study enrollment.