Antitumor activity of trienomycin A on murine tumors

The antitumor activity of a novel ansamycin antibiotic, trienomycin A, against various murine tumors was studied with two treatment schedules. The intraperitoneal injection of the antibiotic showed remarkable antitumor activity on sarcoma 180 and P388 leukemia at doses of 160 or 320 mg/kg, showing 151% and 100% increase in life span, respectively. Trienomycin A inhibited the growth of Ehrlich and Meth A cells in vitro at doses of 0.1-0.4 microgram/ml when the cells were exposed to the antibiotic for 72 hours. The incorporation of [3H]thymidine into acid precipitable material in HeLa cells was slightly more marked than that of [3H]uridine and [3H]leucine when the cells were exposed to 0.04 or 0.08 microgram/ml of trienomycin A for 4 hours. It appeared that trienomycin A showed antitumor activity by direct cytotoxic action.