Gene therapy for tumors of the central nervous system

Primary central nervous system tumors, consisting mainly of malignant gliomas, represent a unique system for the study of gene transfer techniques. Exogenous transgenes have been delivered using retroviral, adenoviral, and herpes simplex virus vectors. A number of strategies have been developed, including: (1) delivery of prodrug activating genes, (2) replacement of tumor suppressor genes, (3) cytokine-mediated enhancement of antitumor immune responses, and (4) antisense cDNA delivery to block the action of growth factors, cell cycle proteins, and drug resistance mechanisms. Efforts to disrupt the blood brain barrier may facilitate tumor gene delivery.