A Phase II clinical study is the second stage of clinical trials in which an investigational therapeutic product is administered to a larger group of patients — typically 100 to 500 — to assess its preliminary efficacy, optimal dosing, and safety profile in the target patient population. Phase II studies provide the proof of concept required to justify progression to Phase III, and are used to refine endpoint selection, patient stratification, and study design. They must be conducted under Good Clinical Practice (GCP) guidelines and in compliance with the approved clinical trial protocol.
