5-Deoxy-5-fluorocytidine-d3 is deuterated labeled 5-Deoxy-5-fluorocytidine (HY-W009538). 5-Deoxy-5-fluorocytidine (5-Fluoro-5-deoxycytidine) is a cytidine analog and metabolite of Capecitabine (HY-B0016). 5-Deoxy-5-fluorocytidine is converted from Capecitabine by carboxylesterase in the liver. 5-Deoxy-5-fluorocytidine is deaminated by cytidine deaminase to generate 5-deoxy-5-fluorouridine, which is finally converted into 5-fluorouracil (HY-90006) by thymidine phosphorylase in tumor tissues to exert anti-tumor effects. 5-Deoxy-5-fluorocytidine is used in the researches for solid tumors such as colorectal cancer, non-small cell lung cancer and breast cancer[1][2][3][4].