Clinical trial treatments typically consist of several phases, with each phase focused on a different purpose. Most of the time, when you take part in a clinical trial, you will only be in that one phase of the study. Treatments move through the phases, but patients do not.
The goal of a Phase I trial is to determine the safety of the new treatment, learn the best way to administer the treatment (orally, intravenously, etc.) and to see whether or not the cancer responds.
Phase I trials usually include 15 to 30 patients, divided into small groups called cohorts. When the first cohort receives a dose of the new drug, doctors may collect blood or urine samples to measure the drug levels.
If no severe side effects present themselves, the next cohort will receive a higher dose of the same drug. This continues with each new cohort until the best dose is determined. With each increasing dose, doctors test each patient to see if he or she is responding to the protocol treatment. If the doctors find that the treatment is safe, then the trial will move forward to be studied in a Phase II trial.
The average length of a Phase I clinical trial can be relatively short due to it being an introductory phase.
Typically, a Phase II trial has less than 100 patients. While the main goal is to see if the treatment works, doctors still closely watch for side effects. If the new treatment works, doctors may go on to study it in a Phase III trial.
The average length of a Phase II clinical trial can range from less than a year to up to two years.
Phase III trials typically include a high number of patients. Hundreds or even thousands of patients around the country or world may participate. Patients enrolled in a Phase III clinical trial will be placed into one of the following groups:
Common questions patients have include:
A computer program will randomly assign patients into groups. This helps to avoid bias in the clinical trial. (Bias happens when human choices affect a study’s results.)
It depends on the trial. For a single blind study, patients do not know which group they are in, but their doctor does. For a double-blind study, neither the patient nor their doctors know which group the patient is in. (In case of an emergency, however, doctors can receive this information.)
A placebo is something that looks like medicine but isn’t. If a placebo is used, it is administered along with the best standard treatment. Using a placebo allows doctors to compare standard treatment alone to standard treatment with a new drug. If there isn’t a standard treatment, then the placebo may be given alone, but this is uncommon.
After the Phase III trial, the FDA reviews the clinical trial results to make sure the treatment is safe and effective for people to use. The FDA decides whether to approve the treatment so that it is available for all patients.
The average length of a Phase III clinical trial can vary, ranging from one to four years or longer.
In Phase IV trials, doctors study treatments that the FDA has already approved. The goal of Phase IV trials is to continue studying any side effects of a new treatment.
The average length of a Phase IV clinical trial is usually shorter than Phase III so typically fewer than four years.
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