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Phases of a Clinical Trial

It is important to know all of your options. Learn about the trials you are eligible for before you start treatment and whenever you need to make a treatment decision.

A new drug or other treatment goes through several different phases of clinical trials prior to Food and Drug Administration (FDA) approval for general use.

Phase I Trials

These first studies in people test how a new treatment should be given (by mouth, vein, through the muscle, inhaled, etc.), how often it should be given and in what dose. Phase I trials also identify safety issues and side effects and usually enroll only a small number of patients.

Phase II Trials

Phase II trials builds on phase I trials and provide additional information about the safety of the treatment being tested and how well it works. In cancer, phase II studies usually focus on a particular type of cancer.

FDA Review

Once a product has successfully completed phase I and II trials, researchers file a New Drug Application (NDA) with the FDA to ask permission to begin phase III. This means that the treatment has been found to be safe and also appears to have a benefit.  

Phase III Trials

These trials compare a procedure or treatment that has shown promise in phase I and II trials with what is currently considered to be the best treatment. The goal phase III clinical trials is to find out if the new approach is better than an already approved treatment. This may mean that it works better, has fewer side effects or is easier to give. Phase III trials typically involve large numbers of patients from all over the world.

Phase III trial participants are usually randomized (assigned by chance) to a group receiving either the new treatment or those getting standard treatment. Neither you nor your physician chooses whether you get the new intervention or the standard treatment.

Those participants in the standard treatment group receive  what experts view as the best treatment available, although there may be situations where the best treatment available is not a treatment at all, but “best supportive care.“ Best supportive care is the term used when the standard practice indicates treatment is complete or when focus is placed on managing pain, discomfort and other disease-related symptoms.

FDA Approval

After the clinical trial phases have been completed, results of the studies are sent to the FDA, which starts the approval process. Cancer drug approval can take some time, but the FDA does look at treatments that appear to be much better than existing treatments first. The FDA tries either to approve a treatment or to respond with comments and issues that must be addressed within 10 months of submission. The FDA expert panel for the approval of cancer drugs called the Oncologic Drugs Advisory Committee (ODAC) meets in open, public meetings to discuss new applications and to provide advice. Each ODAC committee has experts from a variety of research and medical practice fields but also must involve one person who represents the patient perspective.

Post-Market Surveillance

This includes the continuing long-term evaluation that takes place after FDA approval, when the drug or treatment procedure is on the market and available for general use. The purpose is to continue to monitor safety and side effects in a larger group of people. These studies are sometimes known as phase IV trials.

“Off label” Use

After a treatment is approved by the FDA, it may be used by a doctor in any way he or she feels it will be helpful. This is called "unapproved use," an "unapproved indication" or “off label” use.  As a result, a lung cancer patient might be treated with a drug that has been approved for use in another cancer. Based on the doctor’s experience and understanding of the drug, he or she may feel there is a possible benefit for lung cancer. However, some insurance companies will not pay for the use of a therapy that is not approved by the FDA for that particular disease.