fludarabine + thiotepa + methotrexate

Fludarabine + thiotepa + methotrexate is a multi-agent chemotherapy combination, primarily used as a *conditioning regimen* prior to hematopoietic stem cell transplantation (HSCT) and for lymphoma-related protocols. - **Fludarabine** is a purine analog that inhibits DNA synthesis by specifically blocking DNA polymerase, ribonucleotide reductase, and DNA primase, leading to inhibition of DNA replication and repair. - **Thiotepa** is an alkylating agent that crosslinks DNA strands, preventing cell replication and leading to apoptosis. - **Methotrexate** is an antimetabolite and antifolate agent that inhibits dihydrofolate reductase, impeding DNA and RNA synthesis as well as cell proliferation. All three drugs act as potent antineoplastic agents and immunosuppressants, used either together or in combination with other drugs as *conditioning regimens* for transplantation or for the treatment of hematologic malignancies, such as lymphoma or leukemia. The exact combination described—fludarabine + thiotepa + methotrexate—is not a standard named regimen but is pharmaceutically plausible and related to other regimens where two (or all three) are combined for such protocols[4][6][8].