CURATIVE TREATMENTS OF MURINE COLON26 SOLID TUMORS BY IMMUNOCHEMOTHERAPY WITH G-CSF AND OK-432

In order to study the clinical usefulness of biological response modif iers (BRMs) in eliminating malignant solid tumors, we have investigate d the effect of various combination therapies on the murine Colon26 so lid tumor model. When the tumor-bearing mice were treated with chemoth erapeutics, G-CSF and OK-432 (streptococcal preparation), the tumors c ompletely disappeared from all of the treated mice. When these survivo rs were rechallenged with Colon26 tumor cells on Day 120, all of them survived without showing any sign of reccurence or metastases. The res ults indicate that mice with malignant solid tumors, which can not be cured using chemotherapeutics alone, may be completely healed with a c ombination immuno-chemotherapy. During the course of this combination therapy study, it was found that there was a clear positive correlatio n between immunosuppressive acidic protein (IAP) levels and tumor size s. Suppressor macrophages (sM phi) which produce IAP were found to be decreased in bone marrow and spleen of treated mice. This suggests tha t the combination therapy may make the mice recover from a suppressed immune state caused by sM phi. In conclusion, the combination therapy with chemotherapeutics and BRMs could cure the solid tumor-bearing mic e very effectively through not only synergistic direct tumor cell dest ruction but also indirect immunomodulation of the host.