A Phase I trial is the first time that a new investigational treatment is tested in people. Phase I trials include a small group of people who have not been helped by standard treatments. Phase I trials evaluate whether the new treatment is safe, how it should be given (for example, by mouth or by injection), how often, and at what dosage.
Although a Phase I trial is not designed to test how effective a new therapy is, some new treatments tested in Phase I trials do help some patients. In fact, new treatments tested in Phase I clinical trials often shrink tumors or stop the cancer from getting worse. Sometimes a trial that is called a “Phase 1 expansion study” is performed. A slightly larger number of participants receive the new treatment to start to see if there is a benefit with the new therapy, particularly if it shows significant promise. Some recent examples include Xalkori Icrizotinib) for patients with ALK-positive lung cancer and Keytruda Ipembrolizumab) for people with metastatic melanoma.
This is because patients can be matched – based on their mutations or other abnormalities in the tumor – to clinical trials of new treatments most likely to benefit them.
When a new treatment is found to be safe in a Phase I trial, it usually moves to a Phase II trial. A Phase II trial provides information about how well a new drug or treatment works and as well as additional information about how safe the drug is. Patients are treated using the dose and method found to be safest and most effective in Phase I studies. Some Phase II studies randomly assign patients to one of two or more treatment groups, each of which receives a different experimental treatment. These groups may receive different treatments, different doses of the same treatment or the same treatment given in different ways.
Phase III trials are the last phase of clinical testing before a treatment becomes available to the general public. Phase III trials compare new treatments with standard ones to determine which is safer and more effective. Researchers also look to see whether the new treatment helps patients live longer, with a better quality of life, and fewer side effects.
Sometimes clinical trials are performed after the treatment is approved for use in routine clinical care. These are usually done to improve the way the drug is delivered by tweaking a few things. In addition, it may need a better way to select those people that are more likely to benefit. Sometimes treatments are approved early because they are very effective in clinical trials. Regulatory authorities don’t want to hold back highly effective treatments from patients, so they allow them to be used but demand further evidence to support the initial clinical trial results.