“Pharmacokinetic studies revealed that after DFUR administration, plasma DFUR and 5‐fluorouracil (5‐FU) levels rapidly declined, but that, in the combination with l‐cysteine , the plasma clearances of DFUR and 5‐FU were slowed down considerably.”
“Thus, the potency of DFUR was increased by l‐cysteine.”
“When … l‐cysteine, 5′‐deoxy‐5‐fluorouridine (DFUR) brought about a significant reduction in the growth of adenocarcinoma 755 and a significant prolongation of life‐span in mice … increased toxicity to the host as compared with DFUR alone, though l‐cysteine alone did not show an appreciable antitnmor activity.”