Tuesday, November 30, 2010

Utilizing Chinese Medicines to Improve Cancer Therapy - Fiction or Reality?


Abstract:
Despite the tremendous effort on research and development by government and industry, effective treatment of cancer in most patients remains elusive at present. Even if a given chemotherapeutic regimen is very effective at onset, it eventually will fail, due to drug resistance and /or organ toxicity. Thus, there is a great need to incorporate new mode of therapeutic approach in prevention and treatment of cancer. Chinese medicines (CM) have been used in China for about 5000 years for symptomatic treatment of diseases including cancer. The traditional approach of CM is to use different herbal formulae to restore the balance of Yin-Yang of body energy so body function can be normalized. Can this traditional Chinese medicine (TCM) approach provide an alternative to the evidence based conventional cancer chemotherapy? It would be a fiction to expect TCM to substitute as an alternative approach to modern cancer chemotherapy, despite its thousands of years of use in China. However, there are distinct potentials, from theory to herbal compounds, which could be derived from CM. For example, the balance concept of TCM may be an intriguing therapeutic approach for future cancer therapy— aiming not to eradicate all cancer cells but to keep it in balance with normal cells to result in bodily function as close to normal as possible and maintain in such a state as long as possible. Another potential contribution of TCM is its rich source of active anticancer compounds and their combinations which could be developed and proved to be effective therapeutic regimens (or adjunctive regimens) in the future. In tracing the source of new drugs for cancer, more than half of current anticancer agents used clinically in USA are either natural occurring or derived from natural products. These include Vinca alkaloids, taxanes, podophyllotoxin, camptothecins and anthracyclines. Despite the interest in plant-based new drug discovery, only a small portion of more than 250,000 known plant species have been investigated for cancer drug discovery. It is likely that herbs used in TCM can be a useful source of new anticancer drugs. Furthermore, the TCM formulae themselves (which always composed of mixtures of components) may simultaneously target multiple cancer-causing genes/pathways and thus achieve superior effect as compared to single agents aiming for a single molecular target. Nevertheless, before any TCM product can be accepted by the Western world as complementary and alternative medicine for cancer treatment/prevention, it is crucial to identify bioactive components, understand their pharmacological mechanisms, and achieve quality control of a given product along with demonstrating its clinical efficacy. In this issue of Current Drug Discovery Technologies, eight review articles highlighting in more detail some of these important points relating to development of CM as anti-cancer drugs. These articles describe the potential use of the balance concept, examples of CM-derived drugs that have been approved by US FDA and new technology (chemoinformatics) and targets (drug transporters and other molecular targets) as well as TCM products and formulations used for lung cancer. We hope that this special issue will provide a glimpse of examples and new technologies that can be applied toward improving the development of CM, potentially leading to new and effective anti-cancer agents in the future.