All new treatments are tested first in the laboratory. Only treatments that are likely to work in people are tested in clinical trials. First they are tested in a small group of healthy volunteers before giving them to larger groups of patients in clinical trials.

When a new medical treatment is studied for the first time in people, researchers don’t know exactly how it will work. With any new treatment, there are possible risks as well as benefits. Clinical trials help the researchers discover the answers to these questions:

• Is the treatment safe and does it make you feel better?
• How well does the treatment work?
• Is the treatment better than the treatments already available?
• What are the side effects and risks of the treatment?