Biologics Drug Discovery and DevelopmentThe term biologic refers to a diverse group of agents that are produced/obtained from biological sources and/or contain biological components. Much like synthetic pharmaceutical agents, biologics are investigated and developed with the aim of targeting and rectifying pathological mechanisms in the human body. However, while synthetic pharmaceuticals mainly affect cellular signaling through the modulation of receptor-ligand interactions, biologics can exert their effects in a myriad of ways through numerous different mechanisms. Biologic agents currently being used for research and therapeutic purposes range from molecules and peptides (e.g., antibodies and hormones), to intact and functional cells (e.g., stem cells), to 3-D structures such as tissues and organs. Because of this diversity, a firm and comprehensive understanding of how biologic agents will behave in different physiological and pathological conditions (e.g., environments, locations, and cell types) is critical to their effective usage and the prevention of side effects.