Before a therapy can be tested in humans, preclinical research is conducted in the laboratory. If these studies show promise, the sponsor – usually a pharmaceutical or biotechnology company or a research institution – requests permission to conduct clinical trials in people by submitting an Investigational New Drug Application (IND) to the FDA. If the FDA approves, the study will be conducted at one or more medical centers (usually large teaching hospitals).
Clinical trials are conducted in four phases:
Phase 1 clinical trials test the experimental therapy in a small group of people (20-80) to evaluate its safety and identify side effects.
Phase 2 studies test the therapy in a larger group of patients (100-300) to determine how well the treatment works and to further evaluate safety.
Phase 3 trials involve a large number of participants (1,000-3,000). These studies confirm the treatment’s effectiveness, monitor side effects, compare the experimental treatment to standard therapies, and collect information about safety. Successful completion of a Phase 3 study is usually the final step before the sponsor applies for FDA approval to market the therapy.
Phase 4 trials are conducted after the treatment is approved by the FDA and marketed to the public. These studies provide more information about a therapy’s long-term benefits and risks, its impact on patients’ quality of life, its costs relative to its effectiveness, and how it compares to other therapies on the market.
It is important to keep in mind that, at any point in this process, a study may be discontinued if a treatment does not work or has problematic side effects.
