New Cancer Treatments Clinical Trials, Part 2

by National Cancer Institute

(Page 3 of 6)

Phase II: Does the Drug Do What It's Supposed to Do?

Phase II treatment or chemoprevention trials test how well a new treatment (or new use of an existing treatment) works against cancer. In addition, by recording information about the treatment's side effects and complications, researchers learn more about its short-term safety.

In phase II trials, people with specific types of cancer or with certain cancer risk factors are given the medication to see whether or not it has a beneficial effect. Each phase II study usually focuses on 30-50 patients. Phase II bridges the information gap between "is the treatment safe?" to "will it actually work in a specific situation?"

People enrolling in phase II trials may find that beneficial effects, when they occur, may still be mixed with side effects and complications that the researchers did not expect. Only about 33 percent of the drugs tested in phase II trials are found safe and effective enough to go on to phase III.

Phase III: Is the New Approach Better Than Current Medical Practice?

By the time a new cancer approach reaches a phase III clinical trial, it has been shown to be safe at a certain dosage and to be effective against a certain kind of cancer. Now researchers need to figure out whether it is superior to the approaches currently used against that disease. "Superior" can mean that the treatment has a more powerful anti-cancer effect, or that it works just as well but with more acceptable side effects.

To achieve these goals, phase III trials typically enroll several hundred, or even thousands, of people from across the country or around the world. Through a process called randomization, each person is assigned by chance (usually by computer) either to a group that will receive the current standard treatment or a group that will receive the experimental one. Random assignment ensures that participants in the two groups are as similar as possible; only if the groups are similar can their test results be reliably compared to see which approach worked best. Randomization is ethically acceptable because doctors do not know at this point whether the new approach really represents an advance - it might actually work less well than the current standard.

Frequently Asked Questions About Phase III Clinical Trials

Does the way phase III trials are designed mean I might enter a trial and receive no treatment at all?

As already discussed, it is very rare for a treatment trial to be designed with a control group that receives no treatment at all. This might happen only in cases of cancer where there is no effective treatment available. In the vast majority of cases, all participants receive at least the standard treatment.

Prevention trials are different because they enroll healthy individuals with an identified risk factor or factors for developing a specific type of cancer, to test whether or not a drug shows promise in lowering the cancer's incidence. Thus, since few drugs have yet been shown to reduce the risk of cancer, phase III prevention trials typically include a group that does not receive the drug under investigation and one that does. However, once the prevention trial shows that the new drug has a significant effect in preventing the development of cancer, the sponsor will stop the study to make sure that all participants can receive the new drug.

How will I know the risks and benefits before I enter the trial?

Before you can can enter a phase I, II, or III trial, you must go through a process called informed consent. During this process, you would be fully informed about the trial through both a written document and an oral discussion, which review what the trial is meant to test, how long it should last, what procedures will be performed, if randomization is involved, and what is known about the possible risks and benefits. So you would know exactly how the trial is designed and what your chances are of being assigned to any one group.

Those who decide to enroll in a study are willing to accept certain risks (some of which may not even be known) to help evaluate a potentially beneficial new treatment or prevention agent. Some people are not comfortable with this and decide not to enroll. Participation is an individual decision, but in all cases it should be an informed decision.

Let's say I'm in group A in a phase III study and all the patients in group B begin to show marked improvement. What happens to me?

All results are carefully monitored during the trial by a Data Safety and Monitoring Committee, whose members are not connected to the trial in any other way. If early results indicate a clear advantage for one of the groups, the sponsor of the study may choose to end the trial early and establish a protocol allowing wider use of the drug before final approval for marketing. If a drug is shown to have a strongly negative effect, the trial is stopped as soon as this is known.

After the trial is over, can I find out which group I was in?

At the completion of a trial (which may sometimes include follow-up data collection), all patients have access to the results of the study and to information about their own participation. In many cases, however, this information is not available right away. Participants sometimes need to wait for data to be compiled, for other participants to finish their parts of the trial, and for investigators to analyze the results.

How do I find out about participation in clinical trials?

You should consult first with your attending physician about whether participation in such a study is appropriate for you. He or she may already know of a study or be able to direct you to a nearby resource. One of the best online resources is NCI's searchable database of clinical trials 21, which includes information, contact names, and phone numbers for clinical trials being conducted nationwide. Many NCI-designated Cancer Centers across the country also offer access to clinical trials.

About the Author

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