Protection of Normal Tissue against Late Radiation Injury by WR-2721

Abstract

The ability of WR-2721 to protect against late radiation damage has been studied in skin, muscle, and vascular tissues of rats. Animals treated with and without WR-2721 received irradiation to the left hind limb; representative groups were killed at intervals ranging from 72 h to 6 months. Comparison of all drug-treated and non-drug-treated animals showed significant protection (P = less than or equal to 0.05). The time pattern of injury in non-drug-treated rats was biphasic, with significant damage occurring at 72 h and 1 week, returning to normal between 1 and 3 months, but showing significant late damage at 6 months (P = less than or equal to 0.001). Again, this injury pattern did not appear in WR-2721-treated rats. Thus the ability of WR-2721 to protect against acute and chronic radiation injury in vessels, skin, and muscle indicates that an increased therapeutic gain can be expected when this drug is used in clinical radiation therapy.