Some recent findings of chemopreventive agents for the respiratory tract using the hamster and mouse models

ED04-02

Two major strategies for advancing the field of chemoprevention will be discussed. The first focuses on identifying inhibitors that are effective when given at a late stage of precancer and could be administered over a short duration of time. The second deals with selection of agents for development that have been consumed or administered to human populations over a significant period of time with at most producing trivial side effects. Some recent findings pertaining to chemopreventive agents for the respiratory tract using animal models will be cited. For application of chemoprevention to human subjects there is a great advantage of utilizing agents that can be administered over a short period of time. Amongst the advantages is the increased likelihood that the subject will use the chemopreventive agent for a complete course. A second advantage is that a knowledge of the length of the course of administrations will facilitate evaluation and control of adverse effects. Currently most chemopreventive agents are used over a long period of time which is cumbersome and complicated. There are at least two classes of chemopreventive agents that fit the criterion of short duration of administration. One of these is termed interlockers. These are a hypothetical group of agents which act late in the precancer period and have the effect of producing the irreversibility of carcinogenesis which is characteristic of cancer (Wattenberg, Cancer Epidemiology Biomarkers Prevention, 2006; 15, 1425-26). A second group of agents are those which affect tumor formation by aging as described by Campisi and others (Nature, 2006; 643, 1425-26).
 Of great interest are preventive agents for which a high degree of safety has been shown by intake in humans. A search for these has focused on three categories: a) Agents selected on a basis of mechanism. b) In a second group are agents for which there is epidemiological evidence for safety in humans as suggested by structural relationships and c) Compounds reported in literature which is difficult to access because of language or age. Examples of all three categories will be provided. The focus of research on agents likely to have applicability to the human increases the prospects of their ultimate utility for advancing the field of chemoprevention.