The overall objective of this program is ultimately to provide better chemotherapy of human cancer. To accomplish that objective, a coordinated series of multidisciplinary studies will be conducted as follows: 1. Selected compounds synthesized within our Institute and materials from outside will be tested in established experimental tumor systems and several special models for antitumor activity. 2. Additional systems, new or new in our laboratory, will be developed and utilized for antitumor tests, such as a rat colon carcinoma, human cancers in nude mice, neurological tumor models and the spontaneous mammary tumor in CD8F1 mice. 3. The usefulness of available chemotherapeutic agents will be improved by the development of new combination therapy regimens, including added immunopotentiation. 4. Mechanisms of action studies will be conducted on active compounds and in resistant tumor or leukemia lines. 5. Microbiological methods of quantitating levels of certain chemotherapeutic agents in body tissues and fluids to guide therapy schedules in patients will continue to be used and new methods will be developed.