The immunopotentiation effects of the bifunctional radiosensitizer KIN-806in comparison with its analogs KIN-804 and KIN-844

KIN-806 is one of the 2-nitroimidazole derivative hypoxic cell radiosensiti zers. Its radiosensitizing effects and the degree of lung metastasis detect ed were evaluated and compared with its analogs KIN-804 and KIN-844. The im mune reactions induced by these radiosensitizers were also analyzed. Female C3H/He mice and SCCVII tumor cells were used. Seventeen days after inocula tion of SCCVII tumor cells into the animals, 0.4 g/kg of KLN-806, KIN-804, and KIN-844 was administered to each radiosensitizer group 30 min before 40 Gy was delivered as local irradiation. In each group, KIN-806, KIN-804, an d KIN-844 markedly suppressed tumor regrowth in comparison with animals tha t received irradiation alone. There was no significant difference in the ra diosensitizing effects among these three radiosensitizers. A marked suppres sion of lung metastasis and macrophage/T-lymphocyte infiltration into the t umor were observed only in the KIN-806-administered groups, regardless of t he presence or absence of radiation therapy. it therefore appears likely th at the lung metastasis suppression was caused by the immune reaction elicit ed by KIN-806, which is an excellent immunopotentiator as well as an effect ive radiosensitizer.