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 Tegafur

Tegafur (INN) is a chemotherapeutic 5-FU prodrug used in the treatment of cancers. It is a component of tegafur-uracil. When metabolized, it becomes 5-FU. Tegafur-uracil is a formulated therapeutic oral agent consisting of a combination of the 5-fluorouracil (5-FU) congener prodrug tegafur (tetrahydrofuranyl-5-fluorouracil) and uracil (1:4). The high concentration of uracil reversibly inhibits the uracil-reducing enzyme dihydropyrimidine dehydrogenase (DPD), thereby inhibiting first-pass DPD-mediated hepatic metabolism of the uracil analogue 5-FU and permitting administration of 5-FU as the orally bioavailable prodrug tegafur. Tegafur is bioactivated to 5-FU by liver microsomal cytochrome P450 enzymes. 5-FU is subsequently converted into its active metabolites 5-fluoro-deoxyuridine-monophosphate (FdUMP) and 5-fluorouridine-triphosphate (FUTP) intracellularly; these metabolites inhibit the enzyme thymidylate synthase and intercalate into RNA, resulting in decreased thymidine synthesis, reduced DNA synthesis, disrupted RNA function, and tumor cell cytotoxicity. Check for active clinical trials or closed clinical trials using this agent. (NCI Thesaurus).

The UFT combination was developed in the 1980s using tegafur, a pro-5FU drug. Tested and approved in various countries as a therapy for advanced colorectal cancer to replace 5FU, "patients appeared strongly to prefer treatment with UFT/LV over 5-FU/LV."  and has a low cost.  UFT is a first generation DIF, or DPD (DihydroPyrimidine Dehydrogenase) Inhibitory Flouropyrimidine drug. UFT is an oral agent with combines uracil, a competitive inhibitor of DPD, with the 5-FU prodrug tegafur in a 4:1 molar ratio. Excess uracil competes with 5-FU for DPD, thus inhibiting 5-FU catabolism.

The tegafur is taken up by the cancer cells and breaks down into 5-FU, a substance that kills tumor cells. The uracil causes higher amounts of 5-FU to stay inside the cells and kill them. Ftorafur is a type of antimetabolite. The uracil has also been stated to help protect the gastrointestinal tract from 5-FU toxicity and the related metabolites, with less side effects than 5-FU and other 5-FU related (pro)drugs. Trials using UFT for cancer treatment include pancreatic cancer, colorectal cancer, liver cancer, adenocarcinoma of the lung and breast cancer with significant gains over existing treatments, with reduced side effects, improved quality of life, improved disease free survival and/or overall survival. In Japan, China and Korea, papers cite improved success utilizing UFT with cimetidine and/or PSK, both in trials with advanced colorectal cancer, and refractory individual cases of solid tumors with dismal prognoses.

UFT has been administered on a continuous daily basis for 6 to 36 months at 300-400 mg per day in divided doses, in cycles of 5 days dosed at 300 mg/m2 per day, followed by the weekend off, or in cycles of 28 days dosed at 300-600 mg/m2 per day, followed by a week off. The low side effect profile of UFT allows continuous, extended treatments of several years. It is marketed by companies including Merck Serono, Korea United and Taiho, mostly in Asia, Europe, South America, Central America and South Africa.
It is sold under a variety of names including: Tegafur-uracil, UFT, Ftorafur, Tefudex, Ufur and Uftoral. (source: http://en.wikipedia.org/wiki/Tegafur-uracil).