Clinical Trial phases


“Clinical” means that people (as opposed to lab animals) are being tested.

“Trial” means test—we do not yet know if the drug will be safe or effective.

This does not mean that we have no idea if it is safe or effective. Before a Clinical Trial is done, there have been many Research Trials involving animals. There must also be logical reasons to think that the drug will work in humans. The U.S. Food and Drug Administration (FDA) and the EMA (European Medicines Agency) have strict standards that must be met before a clinical trial can enroll patients.

Clinical trials are classified into 4 types or Phases. Each Phase addresses certain questions.

Phase 0: Exploration

  • A few small doses of a new drug in a very small number of patients.
  • Does the drug reach the tumor?
  • How do cells in the human body respond?
  • Not expected to benefit the patient. Might help others in the future.

Phase I: Is it safe?

  • Small number of patients
  • Safety is the main concern. This is usually the first time the treatment has been used in people. But it might benefit the patient.
  • Side effects?
  • Best dose?

Phase II: Does it work?

  • Larger number of patients
  • Effectiveness is the main concern.
  • Safety(Re-check)

Phase III: Is it better than what's already available?

  • Even larger number of patients
  • Re-check safety and effectiveness.
  • How it compares to other treatmentsis the main concern.

Phase IV: Anything else we should know?

  • Continued study after the drug or treatment is approved.
  • Long-term safety and rare side effects are the main concerns.

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