Radiosensitizing effect of misonidazole in fractionated gamma-ray treatment of a human malignant melanoma grown in athymic nude mice

Abstract

The effect of the hypoxic cell radiosensitizer misonidazole (Ro-07-0582) was tested on a human malignant melanoma grown subcutaneously in the athymic mutant nude mouse. A 60Co therapy unit was used for local irradiation of the animals. The tumors were exposed daily to 3.75 Gy [gray] (375 rad) over 4 consecutive days, to a total dose of 15.0 Gy. Misonidazole in doses of 500 mg/kg body wt was administered i.p. in the mice 45 min before each irradiation. The time necessary for the tumors to grow back to their original sizes was compared with that of tumors treated with 4 daily fractions of 3.75, 4.50 and 5.25 Gy without sensitizer. The enhancement ratio of misonidazole was 1.05.