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Understanding Clinical Trials

by Paula Cox, RN, BSN

What is a clinical trial? Most Americans have never heard the term. But for many, understanding what a clinical trial is and how to find out about one can have life saving or life extending implications.

In the following pages there are descriptions of different types of clinical trials, including the three phases through which a drug must pass before it is judged to be safe and effective. The Food and Drug Administration (FDA) is the government agency with the responsibility for overseeing the clinical trial process. In Phase I and Phase II trials are the early stage of drug development, when the safety and dosing levels are tested in a small number of people. Once the safety and some evidence that the drug is effective has been established, the drugs developer then proceeds to Phase III. In Phase III, many more people, usually several hundred are given the drug to see if the safety and effectiveness will be evident in a larger number of people. Phase III is pivotal to learning hard facts about a new drug. Larger number of people reveals the percentage of patients in which the drug is effective, as well as gives doctors a clearer understanding of the side effects that may occur.

At the time of enrollment in a clinical trial, people are usually assured that they will receive either the standard of treatment known for their condition or a treatment that is hoped will be an improvement. Some people considering a clinical trial fear they might receive a placebo, which is not treatment at all. In some cases it is preferable to postpone treatments, therefore "no treatment" can be a standard of care.

Each treatment approach in a trial is referred to as an "arm" of the trial. If you enter a clinical trial often you will be told that you will be randomized to one arm of the study. This means that you will be assigned, generally by a computer so the selection is unbiased, to one of the arms or treatment groups of the study. If during the course of a clinical trial it is discovered that the treatment in one arm is superior to the other arm or arms, the trial is stopped and people in each arm are given the superior treatment.

When you first arrive for a visit regarding a clinical trial, the staff will carefully explain the clinical trial to you, and then give you an explanation in writing, which you will be asked to sign. This process is called Informed Consent.

Why should people participate in clinical trials? The answer is simple. Clinical trials are the only road to progress in improving treatments. When researchers come up with a new treatment, they must prove to their colleagues and patients that the new treatment is better or at least equal to existing treatments. The only way to prove it is to run a clinical trial to demonstrate how the new treatment fares when compared to the standard treatment.

Clinical Trials

Most clinical trials are carried out in steps called phases. Each phase is designed to find different information. People may be eligible for studies in different phases, depending on their general condition, the type and stage of their disease and what therapy, if any they have already had.

Phase I Clinical Trials

The purpose of phase I clinical trials is to find the best way to give a new treatment and how much of it can be given safely. In this phase, a new treatment is given to a small number of patients starting with a very small dose and increasing as more people enter the trial. People are watched closely for any harmful side effects. Although the research treatment has been well tested in the laboratory and in animals, the side effects in humans cannot be completely known ahead of time. Often participants in these trials are those who cannot be helped by any other treatments.

Phase II Clinical Trials

The purpose of Phase II clinical trials are to find out if the treatment controls the disease in humans. If a significant amount of people in the Phase II trial responded (usually about one fifth) then the treatment is judged to be active against that condition or disease. In addition to monitoring people for response, any side effects of the treatment are carefully recorded and assessed. Phase II studies involve larger number of patients than did the Phase I trial.

Phase III Clinical Trials

Phase III clinical trials usually compare to standard treatments (the treatment most accepted) with treatments that appeared to be good in the small Phase II studies. Phase III studies require large numbers of participants; some trials use thousands of patients. Participants are usually randomized, which means that they are assigned by chance to one of the treatments being studied. The group that receives the standard treatment is the "control" group. Phase III studies look for longer life, better quality of life, fewer side effects and fewer cases of the disease returning.

Supportive Care Studies

Clinical trials also try to find better ways of caring for the side effects caused by certain treatments and diseases. Some supportive studies use drugs to treat side effects, some look at support groups, and support innovations.

Group C and Treatment Referral Center Studies

These types of studies make drugs available to some doctors. These drugs have been through clinical trials, have been shown to work, and may soon be approved by the FDA for sale.


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