Prostate cancer (CaP) is among the leading causes of cancer deaths among US men. Developing a successful therapeutic drug to treat hormone- and chemo-therapy refractory advanced metastatic CaP is a major unmet medical need. Several studies have shown that the oxidative stress (OS) in prostate epithelial cells is likely one of the major contributors to CaP occurrence, recurrence and progression to advanced hormone therapy-refractory stage. Therefore, reducing this high level of OS in the prostate gland can be a successful strategy for developing chemotherapeutic and/or chemopreventive drugs for use against CaP. The mitochondria are a major source of superoxide and other ROS. In order to reduce the cellular ROS levels without interfering with the mitochondrial electron transport chain, we focused on targeting spin-trapping nitroxide analogs at the mitochondrial interstitial space with appropriate linker in order to remove the superoxide. Two of our lead compounds in this new class of drugs are CPC-404 and CPC-410. Both blocked androgen-induced OS in human CaP cells and both exhibited marked growth inhibitory effects against androgen-dependent as well as androgen-independent cultured human CaP cells. Based on these results, we propose to develop CPC-410 or its most active analog (a mitochondria targeted compound) as a new chemotherapeutic/chemopreventive drug for CaP treatment.
Our Specific Aims are: 1) to design, synthesize and test CPC-410 and its analogs with anti-oxidant activity against mitochondrial superoxide production and to select the most active analog for maximum anti-proliferative activity against human CaP cells and the least cytotoxic effect against the immortalized normal human prostate epithelial cells (HPEC) in culture, using published protocols, 2) to standardize an effective formulation and route of administration using single intravenous (i.v.) or oral (p.o) administration of the lead drug candidate in preliminary pharmacokinetic studies using a standardized LC-MS protocol, 3) To determine the most efficacious dose of the lead drug candidate in pharmacodynamic studies for reduction of oxidative stress in animal prostate tissues treated with increasing drug doses. The in vivo oxidative stress in animal prostate epithelial cells will be determined following a standardized fluorescence assay for hydroethidine (HEt) dye oxidation after i.v. injection of HEt one hour before sacrifice and harvesting of the prostate gland, 4) To test the chemotherapeutic efficacy of the lead compound in inhibiting the growth of human CaP cell lines androgen-dependent LNCaP and androgen- independent PC-3 xenografts in nude mice and to compare its efficacy with that of docetaxel following published procedures used routinely in our laboratory, 5) To test the chemopreventive efficacy of the lead candidate on the occurrence and growth of spontaneous mouse prostate tumors in Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) animals and to compare its therapeutic efficacy with that of bicalutamide (Casodex).
Advanced Androgen Depletion Therapy (ADT)-resistant metastatic prostate cancer is the second leading cause of cancer deaths among US men. Many prostate cancers are detected as androgen-dependent tumors and are treated by surgery or radiotherapy followed by androgen depletion therapy. Unfortunately, a majority of these patients return with advanced hormone-refractory metastatic prostate tumors that respond poorly to any current conventional cancer therapy. Thus, there is a strong unmet medical need to develop novel therapeutic drugs to prevent the occurrence, recurrence and/or progression of prostate tumors from androgen-dependent to androgen-independent states as well as to treat advanced metastatic androgen- independent tumors. We discovered that certain mitochondria-directed anti-oxidant drugs exhibit very strong anti-proliferative effects against both androgen-dependent and androgen-independent prostate cancer. In preliminary preclinical studies, these drug candidates are well-tolerated by animals. Here, we propose Phase I SBIR pre- clinical studies necessary to identify the lead drug candidate and develop as a clinically useful anti-prostate cancer drug. ? ? ?
