Phases of Clinical Trials

Clinical research involves many stages. The search for new treatments starts in the laboratory, where new ideas are developed and tested. Animal testing often follows laboratory testing. Before patients are involved in clinical trials, an action plan, called a “protocol,” is developed. Each new protocol is thoroughly reviewed by the sponsoring organization as well as an independent institutional review board to ensure patient safety and protection. Particularly when new drugs are being tested, clinical trials are conducted in three phases.

Phase I

Phase I trials typically evaluate how a new drug should be given, how often, and at what dosage. Because a Phase I trial is generally appropriate only for patients with advanced disease that has not responded to standard therapies, most have a small number of participants.

Phase II

Phase II trials primarily test how effective a new drug is against particular types of diseases. Phase III trials compare a new drug or combination of drugs to the standard treatment. The principal question is whether it works better than the current standard treatment or not.

Phase III

Phase III trials can involve thousands of people and may lead to new standards for care.