A. Laboratory activities include the use of accelerator mass spectrometry (AMS) techniques to measure intracellular drugs and drugs metabolites. AMS is a highly sensitive method for detecting tracer amounts of radio-labeled molecules in cells, tissues, and body fluids. We have been able to measure intracellular zidovudine triphosphate (the active anabolite of zidovudine) in peripheral blood mononuclear cells from healthy volunteers given small doses of 14C-zidovudine, and have directly compared the sensitivity of AMS to traditional LC/MS methods carried out in our laboratory. B. Clinical research activities investigate the clinical pharmacology of new anti-HIV therapies and drug combinations. Specific drug classes studied include HIV reverse transcriptase inhibitors, protease inhibitors, entry inhibitors (selective CCR5 and CXCR4 antagonists), and integrase inhibitors. Scientific objectives of clinical studies include characterization of early drug activity, toxicity, and pharmacokinetics. Additional objectives are characterization of pathways of drug metabolism, and identification of clinically significant harmful and beneficial drug interactions mediated by hepatic and intestinal cytochrome P450 isoforms.

The main research goals of my laboratory are: (1) to identify and study the biology of novel cancer selective targets whose enzymatic function can be exploited for therapeutic and diagnostic purposes; (2) to develop methods to target novel agents for activiation by these cancer selective targets while avoiding or minimizing systemic toxicity; (3) to develop novel agents for imaging cancer sites at earliest stages. To accomplish these objectives the lab has originally focused on the development of prodrugs or protoxins that are inactive when given systemically via the blood and only become activated by tumor or tissue specific proteases present within sites of tumor. Using this approach, we are developing therapies targeted for activation by the serine proteases prostate-specific antigen (PSA), human glandular kallikrein 2 (hK2) and fibroblast activation protein (FAP) as well as the membrane carboxypeptidase prostate-specific membrane antigen (PSMA). One such approach developed in the lab consists of a potent bacterial protoxin that we have reengineered to be selectively activated by PSA within the Prostate. This PSA-activated toxin is currently being tested clinically as treatment for men with recurrent prostate cancer following radiation therapy. In a related approach, a novel peptide-cytotoxin prodrug candidate that is activated by PSMA has been identified and is this prodrug candidate is now entering early phase clinical development. In addition, we have also identified a series of potent inhibitors of PSA that are now under study as drug targeting and imaging agents to be used in the treatment and detection of prostate cancer.