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Clinical trials: A chance to try evolving therapies

Keep Taking the Tablets


Clinical trials offer you a chance to try new treatments. Should you participate in a clinical trial? Learn more about how clinical trials work. Courtesy: Mayo Clinic staff

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. Choosing to participate in a clinical trial can be a complex decision. You first need to understand what clinical trials are and how they're used to test new treatments.

What are clinical trials?

Clinical trials are research studies designed to find answers to specific health questions. Clinical trials often look at new drugs or new combinations of drugs (new or old), new surgical procedures or devices, or new ways to use existing treatments. Clinical trials can also look at other aspects of care, such as:

  • Preventing diseases
  • Screening for and diagnosing health problems
  • Quality of life for people with chronic illnesses

Before a new approach can be tested in a clinical trial, it must already have shown some benefit in laboratory testing, animal experiments or in testing with a small group of volunteers.

The goal of clinical trials is to determine if a new treatment both works and is safe. In fact, new medications cannot be sold in the United States until they have been through clinical trials. Therapies that prove effective during clinical trials may go on to become approved and widely available treatment options.

Who can participate in clinical studies?

Researchers are typically looking for people with the specific disease they're studying. Some trials are limited to people who haven't started treatment, while others focus on people for whom standard treatment has failed. Healthy people are needed for some trials. Researchers also consider age, sex and race, among other factors, when selecting people for clinical trials.

Why do people volunteer for clinical trials?

If treatment for your disease isn't available or the standard treatment hasn't worked for you, you might consider a clinical trial. Clinical trials can provide access to new or experimental treatments that otherwise aren't available. However, there is no guarantee that the treatment will be effective for you. In addition, clinical trials may use a placebo — a pill or liquid that looks like the new treatment but has no active ingredients — as a comparison for the drug being tested. You can't control whether you receive the placebo or the new treatment. Despite these caveats, clinical trials offer hope for many people and an opportunity to help researchers find better treatments for people in the future.

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're interested in:

  • Talk to your doctor. Your doctor might be familiar with the drug or therapy involved in the trial. Your doctor 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, as well as its risks and benefits.

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 ensure that you do, the study facilitators provide what's called an informed consent document. You must read and sign an informed consent form before being allowed into the trial. This informed consent document contains information you need to know about the study before deciding whether to participate. Some of the information on an informed consent document includes:

  • What will happen during the clinical trial, including tests you may be given
  • Known risks and benefits of the experimental treatment
  • How long you'll be expected to participate in the clinical trial
  • Other treatments that might be helpful to you instead of the treatment being tested
  • Whom to contact with questions

The form must explain this information in words you can understand. Researchers aren't allowed to pressure you into signing up for a trial. Signing the informed consent form means you agree to participate in the trial. It isn't a contract. If you later decide to leave the study, you may do so without any penalty.

If your child will be enrolled in a clinical trial, you will go through the informed consent process together. As the parent or guardian, you will have to give permission for your child to participate. Depending on your child's age, researchers may also ask your child directly if he or she agrees to be in the study.

Questions to ask before participating in a clinical trial

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?
  • Do the people running the study have a vested interest (conflict of interest) in the outcome?
  • What is this study trying to find out?
  • 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?
  • 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?
  • Who pays if you're unexpectedly injured in the trial?
  • 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?

How are trials conducted?

Clinical trials follow a scientific action plan called a 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 that 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 people 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 looks at issues such as whether the likely benefit of the treatment is worth its risk. If the risks to participants are found to be too great, the IRB can require changes to the study protocol or even reject the study altogether. When reviewing a protocol, the IRB also checks to see if any of the researchers have substantial conflicts of interest.

A clinical trial may also have a data safety monitoring board overseeing it. This board is composed of people who aren't directly involved in conducting the study. The data safety monitoring board can stop the study at any time if they see that the treatment isn't working or it's causing too many side effects. 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 are the stages of clinical trials?

When a treatment is tested in people, it always takes place in stages. Each stage has a different purpose. Treatments being tested must go through the testing in this order:

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 it should be given and how often
  • What is the highest dose that can be given safely
  • How the body reacts to the treatment
  • Any harmful side effects

Earlier studies have often been done only in animals, so the new treatment may pose some risks when first tried in humans. Researchers try to minimize these risks by starting with a very small dose and then increasing it only if no or few side effects occur. Only a limited number of people — typically 20 to 80 — who would not be helped by existing treatments are included in a Phase I trial.

Phase II research
This stage focuses on determining whether a new approach works as intended. For example, does it shrink a tumor? Researchers also monitor participants 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 a Phase II study.

Phase III research
This phase usually begins only after a treatment has shown promise in Phases I and II. At this stage, participants are often randomly assigned — meaning neither you nor your doctor can choose which treatment you receive — the experimental treatment or the standard treatment. Randomization helps to avoid bias in the study's results.

Phase III trials provide more information about the safety of the experimental treatment and demonstrate whether the standard or the experimental treatment has better survival rates and fewer side effects. These trials usually include several hundred to several thousand people. Large trials make it easier to estimate what would happen if the experimental treatment were available to everyone with the condition.

What happens after a clinical trial is over?

After a Phase I or II trial, researchers decide whether to move on to the next phase or stop testing. When a Phase III trial is complete, researchers decide whether the results show enough medical importance that they should be sent to a peer-reviewed, scientific journal. Peer review means other medical experts review the trial to make sure the results are sound.

If the results are promising, the researchers or company they work for may submit an application to the FDA asking permission to make the experimental treatment available to the public. On average the approval process takes about a year, but it can take longer. 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 the FDA approves a treatment. This research, called post-marketing or Phase IV research, tracks the side effects and results in people taking the newly approved drug or treatment. Phase IV trials aren't required for every treatment that's approved, but the FDA can ask a manufacturer to conduct a Phase IV trial to gather additional information about a drug's safety and optimal use. Sometimes companies choose to conduct Phase IV research to compare their product to a competitor's product.

Take time to think through your options

Learning about your disease and how to treat it can leave you feeling overwhelmed. It's important to give yourself time to process all the information about your options. 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.

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