A clinical trial is a research study involving human volunteers, and is designed to answer specific health questions. Carefully conducted clinical trials are the safest and fastest way to find effective treatments, and new ways to improve health.

A drug being studied in a clinical trial is called an investigational drug, and a device being studied in a clinical trial is called an investigational device. An investigational drug may be compared during a trial with a placebo (a substance not expected to have any real medical effect) or to a different treatment.

Clinical trials are conducted according to a plan called a protocol. The protocol describes what types of patients/volunteers may enter the study, schedules of tests and procedures, and additional things like devices or drugs to be used, drug dosages, and length of study, as well as the outcomes that will be measured.

Many clinical trials are done to see if a new drug or device is safe and effective for people to use. Clinical trials are also performed for other reasons. Some compare existing treatments to determine which is better. The current, approved treatments are called the "standard treatments".

Other times clinical trials study different ways to use the standard treatments, so they will be more effective, easier to use, and/or have fewer side effects. Sometimes studies are done to learn how to best use the treatment in a different population, such as children, in whom the treatment was not previously tested.

  • Treatment trials test experimental treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
  • Prevention trials look for better ways to prevent a disease in people who have never had it, or to prevent a disease from returning. The approaches tested may include medicines, vaccines, vitamins, minerals, or lifestyle changes.
  • Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular disease or condition.
  • Screening trials test the best way to detect certain diseases or health conditions.
  • Quality of life trials (or supportive care trials) explore ways to improve comfort and quality of life for individuals with a chronic illness.

Clinical drug trials are conducted in phases. The trials at each phase have a different purpose and help researchers answer different questions.

  • In Phase 1 trials, researchers test an experimental drug or treatment for the first time in a small group (typically 20 to 80 people) to evaluate its safety, determine a safe dosage range, and identify side effects.
  • In Phase 2 trials, the experimental study drug or treatment is given to a larger group of people (typically 100 to 300) to see if it is effective and to further evaluate its safety.
  • In Phase 3 trials, the experimental study drug or treatment is given to large groups of people (typically 1,000 to 3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the experimental drug or treatment to be used safely.
  • Phase 4 trials are conducted on drugs after the US Food and Drug Administration (FDA) has approved them for marketing, in order to provide additional information on the drug's risks, benefits, and optimal use.

Patients enroll in clinical trials for many reasons. These often include interest in advancing science and medical care, interest in gaining access to new, experimental treatments-- especially if all other treatment options have failed–- and also interest in learning more about their medical condition. Some patients may benefit from participating in a clinical trial if the investigational drug turns out to be effective, but there is no guarantee that a volunteer will receive any direct benefit.

By volunteering to participate in clinical trials, participants help advance what we know about medical interventions. In doing so, clinical trial participants can play an important role in getting new drugs and devices approved for use in treating other patients.

It is important to remember that the main purpose of clinical trials is to study new drugs or devices, or new uses of approved drugs or devices, and not to treat patients. Often, drugs or devices must be tested under very specific conditions, so not all patients with a given disease will be able to enroll in a clinical trial.

For each clinical trial, researchers develop eligibility criteria, such as age, sex, the type and stage of disease, previous treatment history, and other medical conditions. These criteria help to reduce the amount of variation in the study, without threatening the scientific integrity of the trial, by removing medical variations that might complicate the analysis of the results.

Not everyone who applies for a clinical trial will be accepted. Volunteers may be excluded based on the eligibility criteria and/or the number of participants needed by the researchers to collect enough information to determine the safety and effectiveness of an experimental therapy. Additionally, a clinical trial for a specific drug or device is typically conducted at a limited number of institutions. Patients who live too far away from a research center may not be able to participate. If a patient is not eligible for a clinical trial or there are none near where they live, the patient may be able to obtain access to an investigational drug outside of a clinical trial.

Even among patients who do participate in a clinical trial, some may be treated with the investigational drug, and some may be treated with a placebo (a substance not expected to have any real medical effect), often along with existing standard of care, or a different therapy for comparison. Drugs that are being tested in clinical trials may prove to be ineffective, or they may have unknown, sometimes serious, side effects.

The clinical trial process depends on the kind of trial being conducted. The clinical trial team includes doctors, research coordinators, and other healthcare professionals. They check the health of the participant at the beginning of the trial, give specific instructions for participating in the trial, monitor the participant carefully during the trial, and follow up after the trial is completed.

For trials conducted at NYU Langone Health, researchers, doctors, and other health professionals administer the clinical trials according to strict rules set by the Federal Office of Human Subjects Protections and the FDA. The federal government sets the rules to make sure that people who agree to be in studies are treated as safely as possible.

Some clinical trials involve more tests and doctor visits than the participant would normally have for an illness or condition. For all types of trials, the participant works with a research team. Clinical trial participation is most successful when the protocol is carefully followed and there is frequent contact with the research staff.

Clinical trials are sponsored or funded by a variety of sources:

  • Federal agencies, such as the National Institutes of Health (NIH), the Department of Defense (DOD), and the Department of Veterans Affairs (VA).
  • Organizations and individuals, such as academic centers, foundations, pharmaceutical and device companies, voluntary groups, and physicians.

The FDA and the Federal Office of Human Research Protections work to protect participants in clinical trials and to ensure that people have reliable information as they decide whether to join a clinical trial. The federal government has regulations and guidelines for clinical research to protect participants from unreasonable risks. Human research conducted at NYU Langone must be reviewed and approved by the NYU Langone Institutional Review Board (IRB).

An IRB is an independent committee of physicians, statisticians, community advocates, and others that ensures that a clinical trial is ethical and the rights of study participants are protected. Research investigators must regularly update the IRB on a study’s progress, including providing prompt reporting of any unexpected serious events. Complimenting the IRB’s responsibilities, the Office of Science and Research provides training for research personnel concerning study conduct and management, and also directly monitors human research.

Although efforts are made to control the risks to clinical trial participants, some risks may be unavoidable because of the uncertainty inherent in research studies involving new medical treatments. Researchers are required to give prospective participants complete and accurate information about what will happen during the trial, so that those interested in participating are fully informed before giving their consent.

Informed consent is the process of learning the key facts about a clinical trial before deciding whether to participate. It is also a continuing process throughout the study to provide information for participants.

To help someone decide whether to participate, the doctors, nurses, and research coordinators involved in the trial explain the details of the study. If the participant's native language is not English, translation assistance can be provided. Then the research team provides an informed consent document that provides written details that were discussed about the study, such as its purpose, duration, required procedures, and key contacts. Risks and potential benefits are also explained in the informed consent document.

This information enables those interested in study participation to make an informed decision about the level of risk they are willing to accept before they enter the trial. The participant then decides whether to sign the document.

Signing the document indicates the potential participant understands that the trial is research and understands its risks and possible benefits, that participation is voluntary, and also formally documents their consent to participate. Informed consent is not a contract, and the participant may withdraw from the trial at any time.

Anyone considering a clinical trial should know that there are both benefits and risks associated with participating.

Potential Benefits

Participating in well-designed and well-executed clinical trials is one way for eligible patients/volunteers to:

  • Get actively involved in their health care.
  • Gain access to potentially new research treatments.
  • Have access to expert medical care for the condition being studied, since investigators are often specialists in the disease area being studied.
  • Help others by contributing to medical research.

Possible Risks

There are generally known and unknown risks associated with clinical trials, such as:

  • Possible unpleasant, serious, or even life-threatening side effects resulting from the study treatment.
  • The treatment may not be effective for the participant.
  • The protocol may require more of the participant's time and attention than a standard treatment, including trips to the study site, more treatments, hospital stays, or complex dosage requirements.

The following questions might be helpful for the participant to discuss with the trial’s health care team. Some of the answers to these questions are found in the informed consent document.

  • What is the purpose of the study?
  • Who is going to be in the study?
  • Why do researchers believe the experimental treatment being tested may be effective? Has it been tested before?
  • What kinds of tests and experimental treatments are involved?
  • How do the possible risks, side effects, and benefits in the study compare with my current treatment?
  • How might this trial affect my daily life?
  • How long will the trial last?
  • Will hospitalization be required?
  • Who will pay for the experimental treatment?
  • Will I be reimbursed for other expenses?
  • What type of long-term follow up care is part of this study?
  • How will I know that the experimental treatment is working? Will results of the trials be provided to me?
  • Who will be in charge of my care?

After all participants have completed the study and all data collected from the trial are properly entered into the trial database, the data can be analyzed to determine the answers to the specific health questions posed by the study.

The types of questions to be answered depend on the purpose of the study. For drug trials, results from early-phase trials (Phase 1 and Phase 2) are used to determine whether a drug should go on to further testing, and to design the later-phase trials. Results from later-phase trials (Phase 3) are used by the FDA to determine whether a drug was shown to be safe and effective, and therefore approvable for marketing to the public.

Acknowledgments: The information above was adapted from the following sources: