title: Antiangiogenic scheduling of chemotherapy improves efficacy against experimental drug-resistant cancer.
abstract: To reveal the antiangiogenic capability of cancer chemotherapy, we developed an alternative antiangiogenic schedule for administration of cyclophosphamide. We show here that this antiangiogenic schedule avoided drug resistance and eradicated Lewis lung carcinoma and L1210 leukemia, an outcome not possible with the conventional schedule. When Lewis lung carcinoma and EMT-6 breast cancer were made drug resistant before therapy, the antiangiogenic schedule suppressed tumor growth 3-fold more effectively than the conventional schedule. When another angiogenesis inhibitor, TNP-470, was added to the antiangiogenic schedule of cyclophosphamide, drug-resistant Lewis lung carcinomas were eradicated. Each dose of the antiangiogenic schedule of cyclophosphamide induced the apoptosis of endothelial cells within tumors, and endothelial cell apoptosis preceded the apoptosis of drug-resistant tumor cells. This antiangiogenic effect was more pronounced in p53-null mice in which the apoptosis of p53-null endothelial cells induced by cyclophosphamide was so vigorous that drug-resistant tumors comprising 4.5% of body weight were eradicated. Thus, by using a dosing schedule of cyclophosphamide that provided more sustained apoptosis of endothelial cells within the vascular bed of a tumor, we show that a chemotherapeutic agent can more effectively control tumor growth in mice, regardless of whether the tumor cells are drug resistant.
authors.affiliation: Children's Hospital, Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
authors.forename: T
authors.initials: T
authors.lastname: Browder
authors.forename: C E
authors.initials: CE
authors.lastname: Butterfield
authors.forename: B M
authors.initials: BM
authors.lastname: Kräling
authors.forename: B
authors.initials: B
authors.lastname: Shi
authors.forename: B
authors.initials: B
authors.lastname: Marshall
authors.forename: M S
authors.initials: MS
authors.lastname: O'Reilly
authors.forename: J
authors.initials: J
authors.lastname: Folkman
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D003315:Cornea / Q000098:blood supply; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D004337:Drug Carriers; D018432:Drug Resistance, Multiple; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D016158:Genes, p53; D007939:Leukemia L1210 / Q000188:drug therapy*; D008081:Liposomes; D008175:Lung Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D008815:Mice, Inbred Strains; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D013868:Thioinosine / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D008081:Liposomes; D013868:Thioinosine; D003520:Cyclophosphamide; D005472:Fluorouracil