FK866 is primarily used in research focused on cancer therapy. It functions as a potent inhibitor of nicotinamide phosphoribosyltransferase (NAMPT), an enzyme crucial for the biosynthesis of nicotinamide adenine dinucleotide (NAD+). By inhibiting NAMPT, FK866 depletes NAD+ levels in cancer cells, leading to energy disruption and ultimately cell death. This mechanism makes it a promising candidate for targeting cancer cells, particularly those with high NAD+ dependency. Studies have explored its potential in treating various cancers, including leukemia, lymphoma, and solid tumors. Additionally, FK866 is being investigated for its role in combination therapies to enhance the efficacy of other anticancer agents. Its ability to selectively target cancer cells while sparing normal cells has garnered significant interest in preclinical and clinical research.