The successful regression of large solid sarcoma 180 tumors by platinum compounds.

successful complete regression of these large tumors in 63 to 100% of the animals. c1L@@@†• Chart 1. Structural diagrams of the 2 platinum compounds found to be active against Sarcoma 180 and Leukemia L1210 in mice: the octahedral complex, cis-Pt(I\')(NH3)@CL@and the square planar com plex, cis-Pt(II)(NH3)2Cl2. MATERIALS AND METHODS Random-bred Swiss white mice, obtained from Spartan Research Laboratories (Williamston, Mich.) were implanted, according to Cancer Chemotherapy National Service Center protocols (1), with a Sarcoma 180 tumor which was original ly obtained from Microbiological Associates, Bethesda, Md., at the request of Mr. S. Poiley of the Cancer Chemotherapy National Service Center staff. This original tumor line passed through 18 transplantations in ICR mice obtained from the Rawley Farms (Plymouth, Mich), and then through 6 further transplantations in random-bred Swiss white mice before these tests. The platinum compounds used in these tests were synthe sized in our laboratory by Mr. Thomas Krigas according to procedures which have been previously published (3, 4). The crystalline platinum compounds were purified by repeated crystallization. The compounds were sent out for analytical tests to the Galbraith Laboratories, Inc. (Knoxville, Tenn.). The sum of the deviations from the predicted values was less than 0.5%. The chemicals were stored in the crystalline state in the dark until the day of use. Solutions of the appropriate strengths were prepared in 0.9% NaC1 solution with distilled water and were injected within a short period of time after preparation to avoid unnecessary photoc.hemical and hydro lytic decomposition of these compounds. SUMMARY The platinum compounds, cis-platinum (IV) diamminotetra chloride, and cis-platinum (II) diamminodichloride, have been reported to be active in inhibiting and regressing small solid Sarcoma 180 tumors and Leukemia L1210 tumors in mice. They were also active in successfully regressing large (Day 8) solid Sarcoma 180 tumors in 63 to 100% of the animals, with no apparent irreversible damage to the host, in a number of dose schedules.