Radiosensitization by misonidazole of a human malignant melanoma grown in athymic nude mice.

Abstract

Abstract A human malignant melanoma grown in the athymic mutant nude mouse has been subjected to acute and fractionated irradiation in the presence and absence of the hypoxic-cell radiosensitizer misonidazole (Ro-07–0582). A 60Co therapy unit was used for local irradiation of nonanaesthetized mice. Misonidazole in doses of 500 mg/kg bodyweight was administered to the mice by intraperitoneal injection 45 minutes before each exposure. In the first series of experiments the enhancement ratio of misonidazole was determined for fractionation regimes with constant interfraction time (one day) and varying number of fractions. For a single dose of 12.50 Gy, three fractions of 4.52 Gy in three days, four fractions of 3.75 Gy in four days and ten fractions of 2.07 Gy in ten days, the enhancement ratio was found to be 1.4–1.5, 1.15, 1.05 and 1.0 respectively. In the second series of experiments the enhancement ratio was determined for fractionation regimes with a constant number of fractions (three) and varying inte...