In association with:

Note: All links within content go to external link
Clinical trials: A chance to try evolving therapies
Special to

You may have heard about clinical trials — studies of possible new treatments or medications — but wonder what exactly they are and if one might be right for you. Whether or not to participate in a clinical trial can be a complex decision. In order to make that decision, it may help you to know more about what exactly clinical trials are and how new treatments are studied and approved for wider use.

What are clinical trials?

Clinical trials are used in all specialties of medicine to test new forms of therapy. They're used to evaluate potential treatments that have had some positive effect against disease in the test tube, animal experiments or in people. Remember that approaches tested in clinical trials may not yet be established treatments. Trials may test new treatment, including new drugs, surgical procedures, medical devices such as pacemakers or stents, radiation therapy or novel approaches to treatment such as gene therapy. Trials may also be done to compare two commonly used, standard therapies to see if one is better than the other.

All research should begin with a basic ethical question: "Do the potential benefits outweigh the potential harm?" Researchers design trials that allow them to learn as much as possible about a new treatment or medication in ways that minimize the risk of injury to participants.

The goal of clinical trials is to determine if a treatment both works and is safe. Therapies that prove effective during trials may become new treatment options. Comparing smaller groups of people taking different treatments for the same type and stage of disease indicates that any benefits are due to the treatment rather than to chance or other factors.

Because research trials are primarily geared toward benefiting future patients with a particular illness, those who take part in the earliest studies of a treatment may not personally benefit from the treatment being tested. However, new therapies may sometimes be effective for study participants.

Who can participate in clinical studies?

Anyone can participate in a clinical trial if they meet the criteria of that trial. Researchers are usually looking for people with the condition the medication is meant to treat. But some trials need healthy people to investigate ways to prevent disease from happening or to determine side effects and effective doses of certain medicines.

Many people take part in a clinical trial because treatments for their condition aren't available. If you've had no luck with standard treatment methods, you might consider a clinical trial as an option. Some people join clinical trials to help people who might develop the same condition in the future.

Each trial has a list of criteria for who can participate, including age, sex and type of disease and its progression. Also important is whether you've been treated for your condition. If an effective treatment for your condition exists, then you aren't likely to be eligible to participate in a clinical trial — you may become eligible if the standard treatment no longer works for you. Some studies are restricted to people who haven't started treatment, while others focus on people who've tried other options first.

In order to ensure the treatment is safe for everyone who might take it, studies need to include people of many races and of both genders. While research was traditionally done only in white men, today it's clear that a greater diversity of research participants is necessary to ensure treatments are safe for everyone.

How do you enroll in a clinical trial?

Your doctor might recommend a clinical trial to you or you might find out about a trial on your own. Often patient advocacy groups let their members know about clinical trials that are recruiting. If you live in a large city, your local newspaper may carry advertisements for clinical trials at nearby research centers. The National Institutes of Health posts listings of thousands of clinical trials online.

Once you find out about a trial you think you may be interested in:

  • Talk to your doctor. Your doctor might be familiar with the drug or therapy involved in the trial. He or she can discuss with you the benefits and risks of the clinical trial and whether you might be eligible to participate.
  • Contact the clinical trial coordinator. This person is often listed with the clinical trial announcement. You or your doctor can take this step. You or your doctor will talk with the study coordinator about your health and whether you meet the criteria for the study.
  • Schedule a pretrial screening. You'll undergo various tests to help the researchers decide whether you qualify for the clinical trial. You'll also get a chance to talk to the investigators about what the trial involves and its risks and benefits.

Not everyone who volunteers is accepted into a clinical trial. Researchers choose participants based on the criteria for the study and the number of subjects needed to collect enough information about the treatment.

How much will you know about the treatment being investigated?

It's crucial that you have enough information about the study and the treatment being investigated to make a well-informed decision. To do this, the study facilitators provide what's called an informed consent document, which contains all of the information you'll need to know about the study before deciding whether to participate. The information should include details about the experimental treatments, tests that may be given, the possible risks and benefits of the tests and experimental treatments as well as information about any standard treatments available for your condition.

Before starting a trial, you must sign an informed consent form. This form explains what will happen during the trial and the known risks and benefits of participating in it. The form must explain this information in words you can understand. Researchers aren't allowed to pressure you into signing up for a trial if you prefer not to get involved.

Signing the informed consent form means you agree to participate in the trial as explained by the researcher and described on the consent form. If you later decide to leave the study, you may do so without any penalty at any time.

In the case of children, the trial participant may not be required to sign an informed consent form. If the participant is a young child, the parent must give informed permission, and the child must agree to enter the study. If the child is unable to agree — for example, if the child is an infant — a parent may consent instead.

If you have any questions about the trial, ask before you agree to participate. Questions you might want to ask include:

  • Who is in charge of this study?
  • What is this study trying to find out?
  • How will this study help in understanding your condition?
  • What will be expected of you?
  • Is it possible that you might receive a placebo?
  • What benefits or risks can you expect if you take part in this study?
  • How long will the study last?
  • What happens if your condition gets worse during the study?
  • What if you don't want to take part in the study? What other treatment options do you have?
  • Can you continue seeing your own doctor during the study?
  • Will you need to pay for any part of the study, including doctor visits and routine tests?
  • How will your participation in the study affect your daily life?
  • What happens at the end of the study?
  • Will you be told the results of the study? When?
  • Who will know that you're participating in the study?
  • Who can you contact if you have more questions?

How are trials conducted?

Clinical trials follow a scientific action plan (protocol). The protocol explains what will be done in the study and why. It outlines:

  • Who may participate
  • How many people will take part
  • What the treatment plan entails
  • The type and frequency of tests
  • How the results will be measured
  • The reasons why a study may be stopped
  • The situations in which researchers may stop giving the treatment to participants
  • The likely or known side effects of the treatment
  • The possible benefits of the treatment

To ensure the safety of those in the study, the organization that sponsors the study, such as the medical center or clinic where the work will be done, must approve the protocol. In addition, an institutional review board (IRB) at each study site reviews the protocol. The IRB includes people from the community as well as health care professionals. It reviews all protocols to be sure that participants are treated humanely and ethically. The IRB also discusses such issues as whether the likely benefit of the treatment is worth its risk.

A data safety monitoring board also oversees the trial. This board is composed of people who aren't involved in the development or administering of the study. The data safety monitoring board can step in and stop the study at any time if members see the treatment has too many side effects or if the treatment isn't helping. A trial can also be halted by the data safety monitoring board if the treatment is proving to be better than the standard treatment. It may be working so well that it should be made available to people outside of the clinical trial.

What types of clinical trials are available?

Before any treatment is tested in people, it must be proved safe and effective in the laboratory or in animals — sometimes called preclinical research. This usually takes one to three years. When a treatment is tested in people, it always takes place in distinct phases. Each phase has a different purpose. Treatments being tested must go through the testing phases in order, including:

Phase I research
This is the first step in testing in humans. At this stage researchers study:

  • How much of the treatment to give
  • How much the human body reacts to the treatment
  • How much can be given safely
  • The best way to give the treatment
  • Any harmful effects

Earlier studies have often only been done in animals, so the approach may pose some risks when first tried in humans. Researchers try to minimize these risks by starting with very small doses, and then increasing the dosage only if no or minimal side effects occur. Only a limited number of people who would not be helped by existing treatments are included in these trials. Between 20 and 80 volunteers typically participate in Phase I studies, which usually last several months. About 70 percent of the drugs tested in Phase I are successful and move on to the second phase of research.

Phase II research
This phase focuses on determining whether a new approach works the way it's intended. For example, does it shrink a tumor or improve the results of cancer-related blood tests? Researchers also monitor you for common short-term side effects that occur with the therapy. Some things aren't yet known about the treatment, so risks are still present. Several hundred people may participate in these studies, which can last from several months to years. On average, 33 percent of the drugs tested in Phase II are successful and move on to the third phase of research.

Some clinical trials may compare a potential new treatment with a placebo — a pill or liquid that looks like the new treatment but has no active ingredients. Before you participate in any trial, you'll be told whether a placebo will be involved. If you agree to participate, you must be willing to take a chance that you'll get the placebo and not the active treatment. Neither you nor your doctor can control which you will receive.

Phase III research
This phase usually begins only after a treatment shows promise in phases I and II. At this stage, you're often assigned randomly to receive either the experimental treatment or the standard treatment. This helps to avoid bias in the results.

Phase III trials provide more information about the safety of the experimental treatment and demonstrate whether the standard or the experimental treatment group has better survival rates and fewer side effects. These trials usually include several hundred to several thousand people and last from one to four years. Large trials make it easier to estimate what would happen if the experimental treatment were available to everyone with the condition. About 25 percent to 30 percent of drugs tested in Phase III are successful and go on to the government for approval.

Phases of clinical studies

Phase Number of participants Length of study What researchers are studying Success rate
Phase I 20-80 Several months Safety 70 percent
Phase II 100-300 As long as two years Effectiveness 33 percent
Phase III 1,000-3,000 One-four years Safety, effectiveness and proper dosage 25-30 percent

Source: National Institutes of Health, 2005, and the FDA Center for Drug Evaluation and Research, 1999

What happens to the treatment after the clinical trials?

After the first three phases have been completed, the company or researcher studying the treatment submits an application to the Food and Drug Administration (FDA) asking permission to make the experimental treatment available to the public. On average, about 20 percent of treatments successfully make it through all phases of research and are approved. Put another way, for every 100 ideas for new treatments, 20 eventually become standards of care.

On average the approval process takes about a year, but it can take several more. Some drugs are approved in a matter of months. These drugs are considered priority drugs — drugs that provide a significant advance in treatment for a life-threatening condition. The FDA's goal is to rule on these drugs no more than six months after they've been submitted for approval.

Sometimes research continues even after a treatment is approved for wide use. This research, called Phase IV research, tracks what happens to people who use an experimental treatment after the FDA has approved it. In these trials, the investigators record the side effects and results occurring in people who undergo a treatment or take a drug. Phase IV studies usually don't include a control group because the treatment has already been approved.

Phase IV trials aren't required for every treatment that's approved. In some cases, the FDA may require that a manufacturer perform the studies when the agency wants to be sure that there are no other side effects or that the known side effects aren't too serious. Sometimes companies launch Phase IV studies with the hope of collecting data that shows their product is better than a competitor's product.

Take time to think through your options

Learning about your disease and trying to decide how to treat it can leave you feeling overwhelmed. Decide whether to participate in a clinical trial only after thinking about your preferences and talking with those close to you, with your doctor and with other health care professionals.

  • Full-body scans: Useful as a screening test?
  • Living wills and other tools to convey medical wishes
  • July 08, 2005

    © 1998-2008 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.  Terms of Use.
    Home  |  World  |  U.S.  |  Politics  |  Crime  |  Entertainment  |  Health  |  Tech  |  Travel  |  Living  |  Money  |  Sports  |
    © 2014 Cable News Network. Turner Broadcasting System, Inc. All Rights Reserved.