Influence of misonidazole on the radiosensitivity of transplantable transitional cell bladder carcinoma in mice.

The radiosensitizing properties of misonidazole (Ro-07-0582; NSC-26137) were evaluated in a leg transplanted model of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) induced transitional cell bladder carcinoma in C3H/He mice. Animals bearing tumor received fractionated radiation of 400 rads X 5 or 600 rads X 5. Other groups with the same radiation doses were treated with misonidazole (0.75 mg per g) before each radiation fraction. Radiation alone was effective in prolonging Mean Survival Time, 17 per cent for 400 rads X 5 and 45 per cent for 600 X 5, with an associated delay in tumor growth. Misonidazole in the 600 rads X 5 group showed a radiosensitizing effect by further slowing tumor growth and prolonging Mean Survival Time by 80 per cent over the control and 24 per cent over radiation alone. Misonidazole alone did not show notable cytotoxic effects.