Induction of a therapeutic antitumor immunological response by intratumoral injection of genetically engineered Semliki Forest virus to produce interleukin-12

The authors investigated immunogene therapy for malignant glioma to determine whether its therapeutic efficacy could be improved. Four groups of 203-glioma-bearing mice were treated with injections of phosphate-buffered saline, Semliki Forest virus (SFV)-LacZ, retrovirus vector DFG-interleukin (IL)-12, and SFV-IL12, respectively. The results indicated that therapeutic immunization with SFV-IL12 prolonged the survival of mice with established tumors. Semliki Forest virus induces apoptotic death to glioma cells, which facilitates the uptake of apoptotic cells by dendritic cells, providing a potential mechanism for enhanced immunogenicity. Immunogene therapy with IL-12 via SFV may be an excellent candidate for the development of new cancer vaccines.