The technical approaches to gene therapy for cancer utilize ex vivo and in vivo gene-transfer methodology. This chapter focuses on applicability and use of an ex vivo approach using an IGF-1 antisense RNA strategy of treatment. Insulin-like growth factor 1 (IGF-1) and IGF-2 have pivotal roles in cell proliferation and development (for review, see 1-6). The preponderance of peptide synthesis and activity occur during fetal development, and protein synthesis is downregulated in most mature tissues except for adult liver. Further modulating the activities of these proteins are the levels of their respective cell-surface receptors and ligand-receptor interactions (3,5,6).