Developing a new drug typically takes 15 years, costs millions, and is often effective only for a portion of patients. When drugs are tested on humans in clinical trials, scientists often can’t predict what the typical effect will be, and don’t understand why different people react in different ways. The failure rate in drug development is over 96%.
Successful drugs work by modifying human biology in a way that slows or halts a disease. However, human biology is extremely complex. When developing new drugs, one of the most difficult challenges is to predict in advance whether the biological changes produced by a therapy will prove to be a safe and effective treatment. In many cases, we still don’t fully understand how some effective drugs work.