Clinical trials typically progress through several phases:
Phase I: Tests the safety, dosage levels, and side effects of a new treatment on a small group of people. Phase II: Focuses on the efficacy of the treatment and further evaluates its safety on a larger group. Phase III: Involves a much larger group of people to confirm efficacy, monitor side effects, and compare the new treatment to standard treatments. Phase IV: Conducted after a treatment is approved by regulatory agencies to monitor long-term effects and gather additional information.