OK-432-combined adoptive immunotherapy as a prognostic factor in peritoneal metastasis from gastric cancer

Prognostic factors, such as preoperative status, intraoperative findings, and postoperative treatments, were evaluated in 61 patients with peritoneal metastasis from gastric cancer treated in our facility between 1979 and 1991. Since 1986, 23 patients have been treated with OK-432-combined adoptive immunotherapy (AIT). OK-432-combined AIT is a sequential treatment via a catheter inserted into the abdominal cavity, using a streptococcal preparation, OK-432, followed by the transfer of lymphocytes cultured with T cell growth factor and sonicated tumor extract. A univariate analysis showed that six factors consisting of: (1) age, (2) resection of primary lesion, (3) grade of peritoneal metastasis or serosal invasion, (4) chemotherapy, (5) OK-432, and (6) OK-432-combined AIT influenced survival. The survival of the patients given OK-432-combined AIT (median survival time; MST = 7.5 months) was significantly (P = 0.0267) longer than that of those not receiving OK-432-combined AIT (MST = 4.3 months). A multivariate analysis showed that the most significant factors associated with survival were chemotherapy, resection of the primary lesion, and OK-432-combined AIT. Since these three factors are all therapeutic procedures, the use of combination therapy including OK-432-combined AIT is thus expected to prolong the survival of gastric cancer patients with peritoneal metastasis.