TFRC and neoplasm: Dosing should maintain plasma serine concentrations > 100 μM to ensure neuronal safety [36].Conversely, CNS tumors necessitate BBB-penetrant nanoplatforms exemplified by transferrin receptor-functionalized siRNA-loaded lipid nanoparticles, which achieve ≥ fivefold tumor-to-normal tissue delivery ratios [95] administered at 1.5 mg/kg weekly across four treatment cycles.