BCAT1 catalyzes the initial transamination of branched-chain amino acids (leucine, isoleucine, and valine), converting them to branched-chain α-ketoacids while generating α-ketoglutarate (αKG), a central metabolic hub. The enzyme localizes to both mitochondrial and cytosolic compartments and plays a critical regulatory role in cellular metabolism beyond simple amino acid catabolism. In cancer contexts, BCAT1 upregulation reprograms metabolism to support tumor growth and aggressiveness. In acute myeloid leukemia, BCAT1 restricts intracellular αKG levels, driving DNA hypermethylation through reduced TET2 activity and promoting leukemia stem cell self-renewal 1. The METTL16/m6A/BCAT1-2 axis is essential for AML initiation and leukemia stem cell maintenance 2. In glioblastoma, synthetic lethality emerges when BCAT1 is inhibited in combination with αKG supplementation 3, while SIRT5-mediated BCAT1 stabilization promotes ferroptosis resistance 4. BCAT1 confers resistance to third-generation EGFR tyrosine kinase inhibitors in non-small cell lung cancer through epigenetic glycolytic activation, and the BCAT1 inhibitor WQQ-345 shows preclinical efficacy 5. BCAT1 also regulates immune responses; inhibition of BCAT1-mediated cytosolic leucine catabolism suppresses Th17 differentiation and ameliorates experimental autoimmune encephalomyelitis severity 6. In macrophages, BCAT1 controls metabolic reprogramming and itaconate synthesis, with the BCAT1 inhibitor ERG240 reducing inflammation-associated disease severity 7.