title: Tumor resistance to alkylating agents conferred by mechanisms operative only in vivo.
abstract: EMT-6 murine mammary tumors were made resistant to cis-diamminedichloroplatinum (II) (CDDP), carboplatin, cyclophosphamide (CTX), or thiotepa in vivo by treatment of tumor-bearing animals with the drug during a 6-month period. In spite of high levels of in vivo resistance, no significant resistance was observed when the cells from these tumors were exposed to the drugs in vitro. The pharmacokinetics of CDDP and CTX were altered in animals bearing the respective resistant tumors. The resistance of all tumor lines except for the EMT-6/thiotepa decreased during 3 to 6 months in vivo passage in the absence of drugs. These results indicate that very high levels of resistance to anticancer drugs can develop through mechanisms that are expressed only in vivo.
authors.affiliation: Dana-Farber Cancer Institute, Boston, MA 02115.
authors.forename: B A
authors.initials: BA
authors.lastname: Teicher
authors.forename: T S
authors.initials: TS
authors.lastname: Herman
authors.forename: S A
authors.initials: SA
authors.lastname: Holden
authors.forename: Y Y
authors.initials: YY
authors.lastname: Wang
authors.forename: M R
authors.initials: MR
authors.lastname: Pfeffer
authors.forename: J W
authors.initials: JW
authors.lastname: Crawford
authors.forename: E
authors.initials: E
authors.lastname: Frei
mesh_terms: D000477:Alkylating Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000818:Animals; D000970:Antineoplastic Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016190:Carboplatin; D002945:Cisplatin / Q000627:therapeutic use; D003520:Cyclophosphamide / Q000627:therapeutic use; D004351:Drug Resistance; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D013438:Sulfhydryl Compounds / Q000032:analysis; D013852:Thiotepa / Q000627:therapeutic use; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured
chemical_list: D000477:Alkylating Agents; D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D013438:Sulfhydryl Compounds; D003520:Cyclophosphamide; D013852:Thiotepa; D016190:Carboplatin; D002945:Cisplatin