Phase II Clinical Trials → Study Design

Phase II research is normally randomised and controlled. The trials typically include between 100-300 participants with the disease or condition of interest. Typically, this phase spans anywhere from a few months to a few years.

The trial can be subdivided into 2 parts: Phase IIa and Phase IIb.

• Phase IIa primarily investigates the efficacy of the drug.
• Phase IIb investigates dosing requirements of the drug candidate, including:
  • Dose response relationship
  • Optimal dosing frequency

After completion of a Phase II Clinical Trial, a sponsor-investigator may ask for FDA guidance on the design of a large Phase III study, if needed.

According to the FDA, only ~33% of drug candidates progress to Phase III.