This document outlines the requirements and contents of an Investigator's Brochure (IB), which is a comprehensive document summarizing clinical and non-clinical data on an investigational product. The IB includes summaries of pharmacology, toxicology, safety and efficacy data from animal and human studies. It also provides guidance to investigators on monitoring patients and outlines a product's risks and important trial precautions. The IB's purpose is to inform investigators of the investigational product's properties to protect patient safety in clinical trials. It is prepared by the sponsor and provided to investigators to review before trials begin.