[Intratumoral administration of OK432 in rats with liver tumor]

The approach to the treatment of unresectable liver tumor involves immunotherapy. Systemic administration of OK432 has been widely used in the treatment of malignant neoplasms. However, the most potent antitumor activity of the drug may be expected when it is administered intratumorally. The author evaluated the effect of intratumoral injection of OK-432 on the survival time, the immunological parameters (such as the NK activities of spleen cells and peritoneal exudate cells and the interferon production by spleen cells) and the tumor infiltrating lymphocytes (TIL) in the rats with liver tumor induced by feeding the hepatocarcinogen, 3'-methyl-4-di-methyl-aminoazobenzene. The mean survival time was significantly longer in the rats injected with OK432 intratumorally (I.T. group) than in the rats injected with OK432 intraperitoneally only (I.P. group) and in the rats injected with normal saline intratumorally (Control group). The immunological parameters significantly improved in the rats of I.T. group than in the controls. Intratumoral injection of OK432 increased the number of TIL, especially NK cells and suppressor/cytotoxic T cells. These beneficial effects could be responsible for the better survival time in the rats of I.T. group. The author concluded that the intratumoral OK432 administration therapy is effective for the treatment of the patients with unresectable liver tumor.