The goal of Annex 3: Case Studies in the Manufacturing of Biotechnological Bulk Drug Substances is to provide detailed examples of characteristic operations and case studies that demonstrate the value of implementing QRM to effectively manage risks during manufacturing of biotechnological bulk drug substances. Each section of this technical report begins with an overview of a stage of the biopharmaceutical manufacturing process and the typical risks associated with that stage, followed by a case study demonstrating how to apply a QRM tool to control, mitigate, and/or eliminate risks during that stage of production. This report also includes a section on the application of QRM to additional factors that can affect biopharmaceutical manufacturing, such as primary contact surface for drug substance, extractables/leachables in the process stream, and environmental controls.