Types of Clinical Trials

Phase 1
This is the first clinical study performed for a new treatment. The trial’s primary purpose is to determine toxicity (side effects) and safety of the treatment. Different dosages are tried to determine the best dose to use for the Phase 2 study. The Phase 2 dose is often the maximally tolerated dose (MTD) during the Phase 1 study, based on toxicity. While effectiveness of the treatment will also be evaluated, that is not the main purpose of the trial. Patients are typically enrolled in a Phase 1 trial when no Phase 3 or Phase 2 trials or other known effective treatments are available.

Phase 2
This is the second stage for evaluating a new treatment. It is a trial to see if the treatment has any effect on the particular disease. Toxicity (side effects) is still monitored quite closely. Patients are typically enrolled on a Phase 2 trial when no Phase 3 or other known effective treatments are available.

Phase 3
This is the third stage for evaluating a new treatment. It is a comparison study between at least two different treatments. It often compares a known, standard treatment to a new treatment strategy, which is hoped to improve outcome. Often, it includes a new drug shown to be effective in a Phase 2 study. Patients are randomly assigned (like flipping a coin) to one of the treatments. If it becomes clear in the middle of the trial that one treatment is better, then the trial will be stopped and patients switched to the better treatment. Most newly diagnosed children with cancer, as well as some at relapse, are treated in Phase 3 clinical trials.

Pilot
This is a clinical trial involving a small number of patients of a new treatment strategy. It is often performed just before bringing the new treatment strategy to a large randomized Phase 3 trial. The main purposes are to assess feasibility of the new approach and to evaluate for any unexpected toxicity (side effects) before enrolling large numbers of patients.

Biological
This is a translational research trial that uses patient samples, such as tumor, blood, or bone marrow, to give researchers more information about diseases and treatments. These trials usually involve laboratory studies conducted on the molecular level. Phase 1, 2, 3, and pilot studies often have biological components.

Epidemiological
This type of trial typically involves the patient or family filling out a written questionnaire. The purpose is to look for genetic or environmental factors that affect why a patient gets a type of cancer and/or how well they respond to treatment.

Quality of Life (QOL)
This type of trial may involve written questionnaires, interviews, or other surveillance tools to assess patients’ quality of life. These trials differ from trials which concentrate on evaluating the direct medical impact of certain treatments or interventions. Instead, the researchers here focus on how a disease and/or intervention for that disease impact on patients’ overall quality of life.

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