SLC22A8 (OAT3) is an organic anion transporter that functions as an organic anion/dicarboxylate exchanger coupling organic anion uptake to the sodium gradient 1. The transporter mediates bidirectional exchange of organic anions such as estrone sulfate and urate for dicarboxylates like α-ketoglutarate, playing a critical role in renal excretion of endogenous metabolites and exogenous drugs 2. SLC22A8 transports diverse substrates including prostaglandins, neuroactive tryptophan metabolites, biopterins, and therapeutic compounds such as cimetidine, penicillin, and statins 1. The transporter is highly expressed in kidney proximal tubules and also functions at the blood-brain barrier and choroid plexus, facilitating detoxification by removing organic anions from cerebrospinal fluid and brain tissue 3. SLC22A8 exhibits significant genetic variation affecting drug disposition; coding variants demonstrate functional heterogeneity, with some causing complete loss of function while others alter substrate specificity 2. Regulatory region polymorphisms containing potential sex steroid response elements suggest variable transcriptional control affecting individual differences in drug and toxin excretion 4. In clear cell renal carcinoma, reduced SLC22A8 expression associates with poor prognosis and elevated immune infiltration, indicating a role in tumor microenvironment regulation 5. These findings establish SLC22A8 as essential for drug disposition, metabolite homeostasis, and potentially tumor immunobiology.