Clinical research is the testing of new treatments in human subjects under carefully controlled conditions. Before a patient is offered the opportunity to participate in a clinical trial, much work and scrutiny has gone into development of the therapy to be tested. From a concept or a discovery in the laboratory to human testing, the treatment must successful pass review by scientists, government regulatory agencies, and finally an Ethics Committee, composed on medical and lay persons. Together with the investigator, they help generate a document called "Informed Consent", which is designed to provide the patient with information about possible risks and benefits of the experimental program.

Clinical testing is conducted in various "phases", which describe both the state of knowledge about the new treatment and the patients who may be asked to participate:

Phase I studies represent the first time a new treatment is tested in humans. In the case of non toxic drugs, these may be performed in normal volunteers, however most anti-cancer remedies are first studied in patients with cancer. The aim of phase I studies is to learn about the possible side effects that can occur - their type, description, duration, and reversibility. Blood and other samples are often taken to determine how the drug is distributed and metabolized by the body, so-called pharmacokinetics and pharmacodynamics. These may provide clues as to the optimal schedule of administration. Since there is potential risk and uncertain benefit to patients in this setting, these trials are made available only to individuals whose tumors have proven unresponsive to standard therapy, or for which there is no proven effective standard treatment. These studies usually include 20-30 patients with a variety of different cancer types. Although phase I studies are very focused on toxicity and drug disposition, evidence of anti-tumor effects are also documented.

Phase II studies use the information gained in Phase I to focus on anti-tumor efficacy. Once the optimal dose and schedule found to be safest is determined, phase II trials are developed to use that dose in groups of patients who have the same tumor type. In non randomized studies including 20-40 subjects, the aim is to measure tumors at various points during treatment, and define precisely how effective the new treatment is. Usually a number of phase II trials are performed, one or two for each of a variety of tumor types. Often additional studies are performed as part of the trial, in order to learn more about the treatment's effects in humans, for example measurement of immune function, changes in the levels of certain proteins in blood or in tumor biopsies, etc.

Phase III studies are where treatments found to have anti-tumor activity in earlier studies are compared to standard therapy in some fashion, using the design called a controlled randomized trial. In order to be sure that only the treatments being tested and no other factors are responsible for the results, patients are randomly assigned to receive one or the other. In order to be ethically and scientifically acceptable, is must be no clear evidence that one is better than the other before the trial begins. Pharmacokinetic studies are sometimes included here in order to examine patient metabolism of the two different treatments in the comparative setting.