AUGMENTED ANTITUMOR EFFECTS OF KILLER-CELLS INDUCED BY TUMOR-NECROSIS-FACTOR GENE-TRANSDUCED AUTOLOGOUS TUMOR-CELLS FROM GASTROINTESTINAL CANCER-PATIENTS

The purpose of this study was to determine the feasibility of a vaccin e therapy using tumor necrosis factor (TNF) gene-transduced autologous tumor cells for the treatment of human gastrointestinal cancers, whic h tend to have lower immunogenicity than other cancers such as melanom a and renal cell carcinoma. We succeeded in establishing primary cultu red tumor cells from 12/54 carcinomatous effusions (4 liver cancer pat ients, 5 gastric cancer patients, 1 pancreatic cancer patient, and 2 c olon cancer patients) and in transducing the TNF gene to the tumor cel ls by using the retrovirus vector MFG-TNF. Even after irradiation, TNF production (0.3-3.5 U/ml per 10(6) cells per 72 hr) was confirmed for 10 of 12 transfectants, and the other two transduced cells were found to have approximately one TNF gene copy. In 7 of the 12 patients, the cytotoxic activity of killer cells to nontransduced autologous tumor cells incubated with these TNF gene transfectants was augmented. This activity was blocked with anti-HLA class I antibody or BrefeldinA (BFA ), suggesting that the killer cells were cytotoxic T lymphocytes (CTL) and tumor antigens are presented with HLA class I molecules. Indeed, enhanced expression of BLA class I and/or ICAM-1 molecules on the surf ace of the TNF gene-transduced tumor cells were observed by fluorescen ce-activated cell sorting (FACS) analysis. Furthermore, natural killer (NK) and/or lymphokine-activated killer (LAK) activities determined b y using K562 or Daudi cells as targets were also enhanced in some of t hese cases when they were incubated with TNF gene-transduced tumor cel ls. These findings indicate the feasibility of using TNF gene-transduc ed tumor cells as a vaccine in gastrointestinal cancer patients.