TUMOR RESISTANCE TO ANTIMETABOLITES

1. The inherent or acquired resistance of certain tumors to cytotoxic drug therapy is a major clinical problem. 2. Resistance to the chemoth erapeutic antimetabolites (e.g., methotrexate, 5-fluorouracil, tomudex and gemcitabine) is no exception. 3. Mechanisms of resistance include mutations, amplification of target genes, altered drug transport, dif ferences in nucleoside and nucleobase salvage pathways, DNA damage-res ponse pathways and cell cycle control pathways. (C) 1998 Elsevier Scie nce Inc.