In agent prevention or chemoprevention trials, people take medicines, vitamins, minerals or other supplements that researchers believe may lower the risk of a certain type of cancer. Many prevention trials are designed to compare a promising new agent with a standard one, or to no agent at all. Participants are randomly assigned to the study or control group.
Phase I chemoprevention trials are usually conducted in a small number of healthy participants or participants at increased risk for a particular type of cancer. The Phase I trials determine dose related safety and agent pharmacokinetic factors including absorption, distribution, metabolism, and excretion. They may also provide some information on agent efficacy.
Phase II chemoprevention trials are conducted in larger groups of participants who are at high risk for certain cancers to further evaluate agent efficacy. Important objectives of Phase II trials may involve identifying and/or validating the physiologic, genetic, or proteomic indicators of cancer risk known as biomarkers. Often Phase II will explore whether the study agent has a desired affect on these biomarkers. In this case, biomarkers can also be used as surrogate endpoints for cancer incidence when chemoprevention trials are unfeasible due to the large number of participants and the length of time required studying the process of preventing carcinogenesis.
Phase III chemoprevention trials are conducted either in populations at high risk for specific cancers or with participants from the general population. Phase III trials are usually large scale, randomized, and controlled to determine the efficacy of an intervention. Phase III trials compare a promising new agent to the standard one or to no agent, using an intervention group, which takes the study agent, and a control group, which takes either a standard agent that is being compared with the study agent, or a look-alike pill that contains no active ingredient (placebo).
DCP also administers pre-clinical programs, including Rapid Access to Prevention Intervention Development Program, to foster cancer prevention agent development and move promising agents from in vitro and animal studies to early clinical trials.