Understanding Clinical Trials


How Clinical Trials Work

Understanding clinical trials and what to expect as a participant

What is a clinical trial?

Clinical trials answer questions about how well a treatment or therapy works and/or how safe it is by monitoring its effect on people (often through bloodwork and other tests, as well as checking for symptoms and side effects). The people in clinical trials are called clinical trial participants and are volunteers who may be healthy or have a specific illness or condition.

Why do we need clinical trials?

Clinical trials are used to determine if the treatment is safe and works as expected in people. The treatment can be a drug, vaccine, medical device, medical procedure, and/or behavioral intervention. Before treatments can be used by the general public, they must undergo a series of clinical trials, called phases, and be approved by regulatory agencies (such as the FDA in the United States and the European Medicines Agency (EMA) in Europe).
Why Do We Need Clinical Trials

The Four Phases of a Clinical Trial

Each clinical trial phase seeks to answer different questions about the treatment being tested and builds upon previous research and results. Usually when you join a clinical trial, you’ll be in just one phase of the trial, however some clinical trials give the option to participate in more than one phase. Clinical trials are reviewed by regulatory agencies for safety and effectiveness, and by ethical review boards. The sections below provide more information about each phase.


Components of a Clinical Trial

Clinical trials are organized into a protocol—a detailed plan for how the trial will be conducted. A protocol includes:
  • The length of the trial
  • Information about the treatment being studied
  • The procedures and tests involved
  • Information about who can participate
  • Rules to be followed
  • The schedule of the trial’s activities
  • How side effects will be managed
Another important document, especially for participants, is the informed consent form (ICF). The ICF explains what you need to know about the trial to make an informed decision on whether you would like to participate in the trial and what you can expect during and after the trial.
Components of the Clinical Trials

How Clinical Trials Are Designed

Clinical trials use different design features, which are in place to help reduce the influence of external factors (such as bias, assumptions, or expectations) on the clinical trial results.


Randomization is the process of assigning trial participants to one of the multiple treatment groups by chance, often using a computer system. Based on the group they are randomly assigned to, participants will receive the treatment being studied, a placebo, and/or a control. Randomization helps avoid bias in a study (e.g., beliefs that may encourage a certain outcome instead of the others).

Controlled Trial

A controlled trial includes a comparison (control) group that receives a ‘comparator’ drug rather than the study treatment (the drug that’s being studied). Commonly, the comparator is the already approved, standard treatment used to treat the condition. Controlled trials help us learn if the study drug is safer, more effective, and/or has fewer or different side effects than the existing effective treatment.


In a blinded trial, one or more roles involved in the trial (such as the participant, the research team, etc.) are kept from knowing which product a participant has received. Clinical trials are ‘unblinded’ upon completion of the study, or when it is no longer needed.


A clinical trial design where the participants do not know whether they are receiving the study drug, placebo, or control, however the research team (principal investigator, clinical research coordinator, etc.) knows.


A clinical trial design where neither the participants nor the research team knows which product the participants are receiving. This is done to help prevent bias or expectations about the treatment groups that could influence the study results.

Open Label

A clinical trial design where both the research team and participants know which drug the participants are receiving.

Types of Clinical Trials


Clinical Trial Safety

It’s understandable to feel uneasy about joining a clinical trial. We value all clinical trial participants and work with the research team to closely monitor participants’ health throughout each trial. We’re dedicated to ensuring trials are designed and conducted following all ethical, regulatory, and legal requirements for your safety. Some measures that are in place to protect participants include:

Your Questions Answered

We're working to discover, develop and deliver innovative therapeutics for people with life-threatening diseases.


We're working to discover, develop and deliver innovative therapeutics for people with life-threatening diseases.

All trials have different timelines due to various factors, such as the trial phase, study design, treatment duration or health condition being studied. During the consent process before enrolling, the research team will explain the specifics about the trial.
Due to the many differences in insurance plans across the country, coverage in clinical trials can vary. You will learn more about your options during pre-screening.
If you don’t qualify due to not meeting the trial criteria, you should check with your healthcare provider to seek other options.
If you are living with a medical condition, joining a clinical trial may give you access to a new potential treatment before it is publicly available. Just as importantly, it can help researchers understand how this potential treatment affects the body and increase their knowledge about the disease and how to treat it. Participation can also play a vital role in helping others who have a similar condition, both now and in the future. Healthy volunteers in trials contribute to this medical progress as well by helping understand the effect of the potential treatment and any safety concerns.
As with all medical records, participant privacy and confidentiality in trials are protected by law. Once consent is signed, you will be given a trial code. Your trial records will not include your name or personal identity but will identify you with a trial code. This code can only be tracked back to you via a code key which is held by the responsible physician. Your name or personal identity will never be disclosed.
Yes, participants are volunteers and may withdraw from a clinical trial at any time.
A placebo is an inactive version of an intervention that is not intended to provide any medical benefit. It is designed to look the same as the active intervention, so the participant and research team do not know it is a placebo. The placebo is used by comparison to confirm any effects of the intervention being studied, if no approved intervention is available.
"Standard of care" is an intervention already approved for a specific health condition that is available publicly. Interventions in a clinical trial are still being tested to ensure safety and effectiveness.
Some clinical trials are designed to be "double blind" so both participants and researchers are unaware of which treatment group participants are assigned to. This prevents bias from affecting clinical trial data.
Your informed consent is required before being enrolled in a trial. This means you have been provided all relevant information about the study design, how you will participate, your right to withdraw at any time, study alternatives, your personal data protection and the associated risks and benefits. Informed consent is designed to protect patient safety and privacy.
Under FDA regulations, an Institutional Review Board (IRB) is a group that has been formally designated to review and monitor research at a hospital or institution involving human participants. In accordance with FDA regulations, an IRB has the authority to approve, require modifications in, or disapprove research.
Participants are always welcome to visit their usual healthcare providers during a trial. Sometimes, it is important for healthcare providers to collaborate with the research team to ensure success.
After your participation ends, the study may continue for months or years. Once final results from all participants are compiled and analyzed, they are often published publicly. Clinical study report (CSR) synopses and plain language summaries (PLSs) may be made available for certain studies. Check with your clinical trial site or send an email to [email protected] to learn more.
There are a wide variety of professionals involved with any clinical trial, all of whom are vital to ensuring safety and success. The principal investigator, or PI, leads the trial and directs the team of doctors, nurses and other healthcare workers. The clinical trial coordinator manages day-to-day activities and is the main contact for participants. Many clinical trials also have an independent Data and Safety Monitoring Board (DSMB) who periodically reviews data to ensure participant safety, and sometimes effectiveness.