The inhibitory potency of facteur thymique serique(FTS) on the mouse metastatic lung cancer induced by Lewis 3LL lung carcinoma cells was investigated. The consecutive treatments with FTS resulted in a significant prolongation of the survival time for mice injected i. v with Lewis 3LL lung carcinoma cells. FTS also suppressed the tumor growth and prolonged the survival time for Ehrlich solid tumor-bearing mice. FTS was fastly cleared from the blood circulation with an initial halfe life of about 10 min after i. p administration. Ganglioside GM1-containing liposomes remarkably increased the blood level and prolonged the halfe life of FTS. A few time of treatment of FTS entrapped liposomes showed the same potency as the consecutive treatments of free FTS in the metastatic lung cancer model. These results suggest that the GM1-liposomes with prolonged circulation time would be useful for the sustained release of drug with a short halfe life.
