The effects of cytokine gene transfer into tumors on host cell infiltration and regression.

New strategies are becoming available that promise to revolutionize cancer immunotherapy. Although the task of generating what is in essence a pathogenic autoimmune anti-tumor response in the face of local and systemic immune suppression is likely to remain a formidable one, advances in molecular strategies for enhancing tumor immunity have been made that show considerable promise, in particular those based on gene transfer technology. For example, introduction of certain cytokine genes into murine tumor cells have been shown to enhance tumor immunogenicity and induce regression. Caution is needed in properly interpreting the relevance of observations derived from murine models for human cancer, but clinical trials are underway that will test the utility of cytokine gene therapy for cancer and that will generate data that will be useful for the design of future strategies. Because of the magnitude of the problem of inducing tumor regression, it is argued that, even if genetically engineering can be used to successfully enhance anti-tumor immunity, combination of such strategies with other existing conventional anti-cancer therapies, that increase the effectiveness of both, may be necessary to reliably achieve cure.