Chronic myelogenous leukemia (CML) is a malignancy which can be successfully controlled by chemotherapy for a number of years. Ultimately, however, all patients develop resistance to drug therapy and their prognosis markedly deteriorates. There is, therefore, an urgent need for the development of new compounds with an improved therapeutic index, information which can explain the mechanisms involved in the development of drug resistance, and the development of alternative drug combinations which can overcome the resistant phase of this disease. This proposal deals directly with these three issues. 1,7-heptanediol disulfamate (Hepsulfam NSC-329680) is an active antileukemic agent that has recently been entered into phase 1 clinical trials by the National Cancer Institute. The mechanism of action of this compound is unknown, therefore, one aim of this proposal is to identify the mechanism by which hepsulfam elicits its antileukemic mechanism. This will be achieved by directly comparing the ability of hepsulfam to induce DNA damage, in human leukemia cell lines, with that of busulfan (a currently used drug of choice in CML) by the technique of alkaline elution. A more detailed analysis of these lesions at the molecular level will be performed. DNA base adducts will be analyzed by high pressure liquid chromatography and identified by mass spectroscopy. DNA sequence specificity of this agent will be analyzed by both Maxam and Gilbert and Sangers dideoxy sequencing methods. A human leukemic cell line, with acquired resistance to either busulfan or hepsulfam, will be established. This will allow a careful analysis of the cross-resistance patterns that might be expected to occur clinically. In addition, the importance of detoxification or DNA repair, as mechanisms of drug resistance in CML, will be assessed. Finally, this information will be used in order to develop more effective therapeutic combinations with which to treat CML.
