leucovorin + vincristine + fluorouracil + doxorubicin

This is a **combination chemotherapy regimen** consisting of four individual agents: leucovorin (a folinic acid derivative, not itself chemotherapeutic, but used to potentiate the effects of fluorouracil), vincristine (a vinca alkaloid mitotic inhibitor), fluorouracil (5-FU, an antimetabolite inhibiting thymidylate synthase), and doxorubicin (an anthracycline antineoplastic that intercalates DNA and inhibits topoisomerase II). - **Leucovorin** is given to enhance the cytotoxic action of fluorouracil by stabilizing the binding of fluorouracil metabolites to thymidylate synthase[5][6]. - **Vincristine** disrupts microtubule assembly, arresting mitosis. - **Fluorouracil** is a pyrimidine analog that inhibits thymidylate synthase and DNA synthesis. - **Doxorubicin** intercalates DNA, inhibits topoisomerase II, and generates free radicals. This combination is not a widely recognized or standardized protocol in major oncology references or regimen listings[3], but the individual components are used in various multi-agent chemotherapy regimens for several cancers, including breast cancer, lymphoma, and others[2][3]. A regimen close to this combination has been studied for advanced breast cancer in limited trials[1], but it is not a standard named regimen.