[Immunotherapy of gastric cancer]

Two immunotherapeutic methods were developed as adjuvant therapy for gastrointestinal malignancies, one using oral administration of a streptococcal preparation, OK-432, and the other with adoptive immunotherapy (AIT), local transfer of IL2-cultured and autologous lymphocytes, combined with local preadministration of OK-432. Tsuchitani and Nio in our laboratory have revealed experimentally that oral OK-432 stimulates tumor-specific and non-specific immune mechanisms of gut-associated lymphoid tissues and inhibits the growth of some murine syngeneic tumors that were transplanted into cecal patches. The clinical efficacy of oral OK-432 on gastric cancer patients has been examined by a controlled randomized trial involving a total of about 1000 cases. Oral OK-432 (5KE, once a week) was revealed to be significantly effective in curatively resected group but not effective in non-curatively resected group. Ten consecutive patients with peritoneal dissemination of gastric cancer were treated with intraperitoneal OK-432 and AIT. AIT was performed by transferring autologous lymph node-lymphocytes cultured for 13 days with crude IL2 and tumor-extract. The survival of the treated patients was significantly longer (50% survival period exceeded 1 year) than that of historical control (95 cases, 50% survival period was 5 months). These immunotherapeutic methods are expected to be useful for multidisciplinary therapy of gastric cancer by a combination of each method with other therapeutic methods.