SLC7A5 (LAT1) is a large neutral amino acid transporter that mediates the uptake of essential amino acids including leucine, tryptophan, and phenylalanine across the plasma membrane. The transporter functions as part of a heterodimeric complex with SLC3A2 and plays a central role in mTORC1 signaling activation, which governs cellular growth and metabolism. SLC7A5 is substantially upregulated in multiple cancer types and supports the elevated metabolic demands of malignant cells. In acute myeloid leukemia (AML), high SLC7A5 expression correlates with increased branched-chain amino acid accumulation and leukemia stem cell function 1. In triple-negative breast cancer (TNBC), LAT1 promotes de novo NAD+ synthesis via L-tryptophan uptake, thereby enhancing glycolytic enzyme activity and tumor progression; elevated LAT1 levels associate with poor survival and chemoresistance 2. Similar upregulation occurs across thyroid cancer subtypes, where SLC7A5 expression increases irrespective of molecular subtype and contributes to altered metabolic phenotypes 3. LAT1 expression is largely cancer-specific, with notable exceptions in the placental and blood-brain barriers 4. SLC7A5 inhibition represents a therapeutic strategy for multiple malignancies. The selective inhibitor JPH203 suppresses AML cell growth and synergizes with venetoclax and azacitidine 1, while also enhancing doxorubicin sensitivity in TNBC 2. Recent cryo-EM structures clarify how JPH203 and other inhibitors block LAT1 function 5, supporting rational drug design. Additionally, SLC7A5 serves as a companion diagnostic target, enabling cancer-specific detection via the LAT1-specific PET probe FAMT 4.