leucovorin + mitomycin C + tegafur + uracil

This is a multi-agent chemotherapy regimen composed of four drugs: - **Leucovorin** (folinic acid), which enhances the cytotoxic effects of fluoropyrimidines by stabilizing the binding of 5-fluorouracil (5-FU) to thymidylate synthase. - **Mitomycin C**, an antitumor antibiotic that acts as an alkylating agent, cross-linking DNA and inhibiting DNA synthesis. - **Tegafur**, a prodrug that is converted in the body to 5-FU, a pyrimidine analog that inhibits thymidylate synthase and disrupts DNA synthesis. - **Uracil**, which competitively inhibits dihydropyrimidine dehydrogenase (DPD), thereby increasing and prolonging systemic exposure to 5-FU derived from tegafur. The combination leverages synergistic mechanisms for enhanced antitumor activity. Tegafur/uracil plus leucovorin is used as an oral alternative to intravenous 5-FU/leucovorin regimens, with mitomycin C added for further cytotoxic effect. This regimen has been studied primarily in metastatic or recurrent colorectal cancer and nasopharyngeal carcinoma, especially as salvage therapy after standard treatments have failed[6][8][1]. The combination aims to maximize tumor response while maintaining manageable toxicity profiles.