Regression of human tumors established in nude mice after continuous infusion of thymidine

A system for the continuous infusion of thymidine solutions in nude mice has been developed. High doses (0.5 to 1.0 ml/mouse/hr) of a 28.5-mg/ml thymidine solution (444 to 888 mg/kg/hr) can be administered continuously for 96 to 140 hr. The preliminary results indicate that it is possible to induce total tumor regression of human heterotransplants established in nude mice of one human teratocarcinoma, five different human melanomas, and one human lung carcinoma and to inhibit to a large degree the growth of two human breast carcinomas by multiple (two to eight) cycles of infusion. The life span of the thymidine-treated animals has been significantly increased compared to that of control animals.