The goal of this project is the development and application of bioanalytical methods to: (1) establish the structure and purity of new antitumor agents and their metabolites, (2) determine physical, chemical and biochemical properties of new anticancer drugs and (3) measure drugs and their metabolites in biological samples to elucidate in vitro and in vivo pharmacology and to determine in vivo pharmacokinetics. Mass spectrometry, gas chromatography and high-performance liquid chromatography, either alone or in combination, are emphasized analytical approaches. Current studies (biochemistry, preclinical pharmacology, and toxicology) are focused on cyclopentenyl cytosine (CPE-C), a carbocyclic nucleoside whose Phase I clinical trial has been suspended because of severe and unpredictable hypotension. A retrospective analysis of human pharmacokinetics indicated no parameter which was indicative or predictive of hypotension. CPE-C continuous infusion studies in dogs with hemodynamic and pharmacologic monitoring produced similar pharmacokinetics, including equivalent intracellular production of the active metabolite, cyclopentenyl cytosine triphosphate, but no hypotension. Biochemical studies have further defined the in vitro time course of cytidine rescue from the cytotoxicity of CPE-C and have shown that cytidine rescue does not affect antitumor activity in mice. CPE-C was rapidly phosphorylated in vitro by a human glioblastoma cell line and possessed an IC50 of ca. 0.1 micro M for both cell proliferation and depletion of CTP pools. Direct, intracerebral infusion of CPE-C into malignant 9L gliosarcoma tumors in rats resulted in significantly increased survival relative to controls.
