This symposium will discuss the four pillars that support a comprehensive operational feasibility assessment for clinical trial planning from a CRO and sponsor perspective: Internal/proprietary data analysis, commercial/publically available data analysis, primary investigator and patient research, and industry expert input/guidance. In addition, we will provide details regarding the limitations of primary investigator research at early stages of clinical planning, including a specific quantitative analysis of investigator estimates at the feasibility stage versus actual enrollment performance during study participation. Finally, we will discuss areas of opportunity for leveraging the value of investigator input and provide specific examples of how this has been done successfully from a sponsor perspective.