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Phase II Clinical Trials → Study Goals

Phase II focuses on the effectiveness of the drug in the population who have the specific disease/condition that the drug is being investigated for. Although there are a few hundred participants in Phase II, it is not enough to determine clear benefit of a drug candidate; that is reserved for Phase III.

The goals of a Phase II trial include:

  • Evaluating efficacy of the drug: To determine that the drug is effective for the population it is intended for and aims to answer the questions:
    • Is it working as intended for the condition?
    • Is there a dose-response relationship with the medication?
    • What dosage works best?
    • What formulation works best?
    • How often should the medication be taken?
  • Further evaluating the safety of the drug: Although Phase I’s main focus is safety, some longer-term side effects may not be identified until Phase II, and even Phase III. Phase II also includes a larger sample size, increasing the researchers’ ability to detect rare side effects. Therefore, one of Phase II’s main goals is to further evaluate the safety of the drug.
  • Evaluate the benefit-risk profile: This evidence supports continuation towards Phase III, as well as guides the Phase III study design.

Phase II studies may be terminated for reasons including insufficient efficacy, serious/unexplained safety events, evidence of damage to tissues, organs, or cells, drug-drug interactions, or efficacy only seen in smaller populations.