Understand The R&D Process

Clinical Trials

Clinical trials refer to the research stage in which potential therapy is tested and monitored in humans. There are 3 stages of clinical trials required before a therapy can be approved and marketed (sold) for use outside a research or clinical study. In addition to supporting clinical trial recruitment and engaging with the FDA, you or others in your patient community may be interested in becoming a member of one of the boards involved in review and monitoring of clinical trials.

  • Institutional Review Boards (IRBs) and Data Safety and Monitoring Boards (DSMBs) both play important, though different, roles in reviewing and monitoring each phase of a clinical trial
  • Phase 1: The therapy is tested in a very small group of  healthy volunteers (or sometimes patients) to confirm it is safe to use in humans, as well as to determine the therapeutic dosage. This phase usually lasts a few months. 
    • According to the FDA, about 70% of therapies move on to Phase 2.
  • Phase 2: The therapies is tested in a small group of patients (up to several hundred) to determine whether it is effective and whether there are side effects. This phase can last anywhere from several months to 2 years.
    • According to the FDA, only 33% of therapies move on to Phase 3.  
    • Many therapies fail in Phase 2 because they are found to be ineffective or produce unpredicted safety issues or serious side effects. 
  • Phase 3: The therapy is tested in a larger group of patients (from a few hundred to several thousand) to continue to gather data on the effectiveness, as well as to monitor for adverse reactions. This phase usually lasts 1 to 4 years. 
  • Rare diseases: When a disease is rare, certain allowances during the clinical trial process may be allowed by the FDA. For example, the number of patients required for a specific clinical trial phase will usually be much lower than required for a more common disease.
  • NCATS Toolkit provides more information on clinical trials, including other key areas your group can support the process in Clinical Trials and FDA Review.


Preparation for Clinical Trials
Developing Products for Rare Diseases & Conditions U. S. Food and Drug Administration (FDA) (link)
Tips to Learn More
How Does FDA Approve a Drug U. S. Food and Drug Administration (FDA) (link)
The Drug Development Process U. S. Food and Drug Administration (FDA) (link)
The Device Development Process U. S. Food and Drug Administration (FDA) (link)
CDER Learn Training and Education U. S. Food and Drug Administration (FDA) (link)
Drug Approval: Bringing a New Drug to the Market U. S. Food and Drug Administration (FDA) (link)
European Patients' Academy European Patients' Academy on Therapeutic Innovation (link)