9 Nitro-20(S) camptothecin propionate (9NCP) is a potent antitumor agent which works through ingibition of topoisomerase I. The investigators anticipate that it will be effective against a variety of cancers. A Phase I study will be conducted at M.D. Anderson Cancer Center to find the maximum tolerated dose. The aim of the study at the UCRC is to perform a pharmacology study of 9NCP after oral absorption. Camptothecin has a labile lactone ring (active form) which can be opened to give a carboxylate form (inactive form) in the presence of human albumin, or at basic pH. A proprionate side chain has been added to the camptothecin, to protect the lactone form. The investigators will measure the amount of drug that remains in lactone form after oral absorption. For this, samples of blood will be drawn at specific times after drug intake, for a period of 72 to 120 hours. Samples will be analyzed for the lactone and total drug content. A computerized pharmacology program will be utilized to estimate the area under the curve, T max, C max, and total body clearance.