KMO (kynurenine 3-monooxygenase) is a mitochondrial enzyme that catalyzes the hydroxylation of L-kynurenine to form 3-hydroxy-L-kynurenine, playing a crucial role in the kynurenine pathway of tryptophan metabolism 1. This enzyme is essential for quinolinic acid synthesis and regulates immune function, neuronal signaling, and inflammation 1. KMO exhibits significant disease relevance across multiple conditions. In cancer, dysregulated KMO contributes to creating immunosuppressive tumor microenvironments that promote immune evasion 2. In atherosclerosis, KMO is upregulated in unstable plaques and positively correlates with M0 macrophages while negatively correlating with CD8 T cells, making it a potential diagnostic biomarker for plaque instability 3. In stroke recovery, KMO suppression enhances mitochondrial fusion and inhibits mitophagy, promoting brain repair 4. KMO genetic variants are associated with substance use disorders and Parkinson's disease susceptibility 56. Clinically, KMO represents a promising therapeutic target, with inhibitors showing potential in cancer immunotherapy, inflammatory bowel disease, and colorectal cancer treatment 17. The enzyme's role in modulating immune responses and metabolic pathways makes it an attractive target for multiple therapeutic interventions.