zd-6126 and Carcinoma--Squamous-Cell

The effect of vascular disrupting agent ZD6126 with time on the sensitivity to the hypoxic cytotoxin tirapazamine (TPZ) and gamma-rays was examined in large and small solid tumors.. Mice bearing SCC VII tumors 1 or 1.5 cm in diameter received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all proliferating (P) cells, followed by injection with or without ZD6126. In the absence of ZD6126, or 1 or 24 h following ZD6126 injection, the response to TPZ or gamma-ray irradiation in quiescent (Q) cells was assessed in terms of induced micronucleus (MN) frequency using immunofluorescence staining for BrdU. The MN frequency in the total cell population was determined from the tumors not pretreated with BrdU. Another group of tumor-bearing mice received a series of test doses of gamma-rays while alive or after tumor clamping to obtain hypoxic fractions (HFs) in the tumors.. One hour after ZD6126 injection, both small and large tumors showed lower and higher sensitivity, and 24 h after, higher and lower sensitivity, to gamma-rays and TPZ, respectively, than the tumors not treated with ZD6126. Further, they showed larger and smaller HFs 1 and 24 h after ZD6126 injection, respectively. Without ZD6126 and 1 h after injection, small tumors were more sensitive to gamma-rays and less sensitive to TPZ than large tumors, probably due to the smaller HFs than large tumors. In contrast, 24 h after the injection, these differences in sensitivity and the HF between small and large tumors were reversed. The changes in sensitivity and the size of the HF were more marked in the total cell population than in Q cells.. Following ZD6126 treatment, in terms of tumor control, especially large tumors and total tumor cell population, administering TPZ 1 h later and gamma-ray irradiation 24 h later were effective. Intratumor physiologic factors such as the size of the HF, depending on the time after ZD6126 injection, have to be taken into account when combining another treatment with ZD6126.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Line, Tumor; Gamma Rays; Mice; Organophosphorus Compounds; Radiation-Sensitizing Agents; Radiotherapy Dosage; Time Factors; Tirapazamine; Triazines

To examine the antivascular and antitumor activity of the vascular targeting agent ZD6126 in combination with radiation in lung and head-and-neck (H and N) cancer models. The overall hypothesis was that simultaneous targeting of tumor cells (radiation) and tumor vasculature (ZD6126) might enhance tumor cell killing.. A series of in vitro studies using human umbilical vein endothelial cells (HUVEC) and in vivo studies in athymic mice bearing human lung (H226) and H and N (squamous cell carcinoma [SCC]1, SCC6) tumor xenografts treated with ZD6126 and/or radiation were performed.. ZD6126 inhibited the capillary-like network formation in HUVEC. Treatment of HUVEC with ZD6126 resulted in cell cycle arrest in G2/M, with decrease of cells in S phase and proliferation inhibition in a dose-dependent manner. ZD6126 augmented the cell-killing effect of radiation and radiation-induced apoptosis in HUVEC. The combination of ZD6126 and radiation further decreased tumor vascularization in an in vivo Matrigel angiogenesis assay. In tumor xenografts, ZD6126 enhanced the antitumor activity of radiation, resulting in tumor growth delay.. These preclinical studies suggest that ZD6126 can augment the radiation response of proliferating endothelial H and N and lung cancer cells. These results complement recent reports suggesting the potential value of combining radiation with vascular targeting/antiangiogenic agents.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Carcinoma, Squamous Cell; Caspases; Cell Line, Tumor; Cell Proliferation; Collagen; Combined Modality Therapy; Drug Combinations; Drug Screening Assays, Antitumor; Endothelial Cells; G2 Phase; Head and Neck Neoplasms; Humans; Laminin; Mice; Mice, Nude; Neovascularization, Pathologic; Organophosphorus Compounds; Proteoglycans; Random Allocation; S Phase; Umbilical Veins

Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or with neo vector as a control (SAS/neo) were inoculated subcutaneously into both the hind legs of Balb/cA nude mice. Mice bearing the tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all proliferating (P) cells in the tumors. The mice then received a hypoxic cytotoxin, tirapazamine (TPZ) or TX-402, with or without a vascular targeting agent (VTA), ZD6126. Another group of mice given ZD6126 received a series of test doses of gamma-rays while alive or after tumor clamping to obtain hypoxic fractions (HFs) in the tumors. After each treatment, the tumor cells were isolated and incubated with a cytokinesis blocker (cytochalasin-B), and the micronucleus (MN) frequency in cells without BrdU labeling [quiescent (Q) cells] was determined using immunofluorescence staining for BrdU. The MN frequency in total (P+Q) tumor cells was determined from the tumors that were not pretreated with BrdU. Both hypoxic cytotoxins showed significantly greater toxicity toward SAS/mp53 and Q than SAS/neo and total tumor cells, respectively. The sensitivity to TX-402 was significantly higher than that to TPZ in both total and Q tumor cells of both tumors. The significant enhancive effect by ZD6126 combined with each hypoxic cytotoxin was similar irrespective of p53 status, and slightly greater for total than Q cells probably because of a more marked increase in the size of the HFs in total than Q cells on the use of ZD6126 in both tumors, resulting in a reduction of the difference in the sensitivity to the hypoxic cytotoxin between total and Q cells. In the treatment of conventional cancer therapy-resistant Q tumor cells or p53-mutated tumor cells, the use of hypoxic cytotoxin was very promising either alone or when VTA was co-administered. TX-402 might be more promising than TPZ, although further study of the toxicity to normal tissue is needed.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Squamous Cell; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Cell Survival; Combined Modality Therapy; Cyclic N-Oxides; Gamma Rays; Head and Neck Neoplasms; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Micronucleus Tests; Mutation; Organophosphorus Compounds; Quinoxalines; Radiotherapy; Tirapazamine; Triazines; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays

The aim of this study was to evaluate the antitumor efficacy of the vascular targeting agent ZD6126 (N-acetylcochinol-O-phosphate) in the rodent squamous cell carcinoma (SCC) VII carcinoma model, in combination with boron neutron capture therapy (BNCT).. Sodium borocaptate-(10)B (BSH, 125 mg/kg, i.p.) or l-p-boronophenylalanine-(10)B (BPA, 250 mg/kg, i.p.) was injected into SCC VII tumor-bearing mice, and 15 min later, ZD6126 (100 mg/kg, i.p.) was administered. Then, the (10)B concentrations in tumors and normal tissues were measured by prompt gamma-ray spectrometry. On the other hand, for the thermal neutron beam exposure experiment, SCC VII tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells in the tumors, followed by treatment with a (10)B-carrier and ZD6126 in the same manner as the above-mentioned (10)B pharmacokinetics analyses. To obtain almost similar intratumor (10)B concentrations during neutron exposure, thermal neutron beam irradiation was started from the time point of 30 min after injection of BSH only, 90 min after BSH injection for combination with ZD6126, 120 min after the injection of BPA only, and 180 min after BPA injection for combination with ZD6126. Right after irradiation, the tumors were excised, minced, and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the micronucleus (MN) frequency in cells without BrdU labeling (quiescent [Q] cells) was determined using immunofluorescence staining for BrdU. Meanwhile, the MN frequency in total (P + Q) tumor cells was determined from the tumors that were not pretreated with BrdU. The clonogenic cell survival assay was also performed in mice given no BrdU.. Pharmacokinetics analyses showed that combination with ZD6126 greatly increased the (10)B concentrations in tumors after 60 min after BSH injection and after 120 min after BPA injection. The concentrations of (10)B from BSH in normal tissues were also raised by combination with ZD6126, although not so clearly as those in tumors. Combination with ZD6126 had almost no effect on the concentrations of (10)B from BPA in normal tissues. The clonogenic surviving fractions of total tumor cells and the MN frequencies of both total and Q tumor cells were reduced and increased by combination with ZD6126, respectively, whether BSH or BPA was employed. However, the degrees of these changes in the clonogenic surviving fractions and the MN frequencies were more obviously observed in tumors from BSH-injected mice than from BPA-injected mice, and in Q tumor cells than in total tumor cells regardless of the employed (10)B-carrier.. Combination with ZD6126 was regarded as more promising in BSH-BNCT than BPA-BNCT, and more effective for enhancing the sensitivity of the Q tumor cells than that of the total tumor cells. This resulted in the decrease in the extended difference in the sensitivity between the total and Q tumor cells caused by the use of (10)B-carrier for BNCT.

Topics: Animals; Borohydrides; Boron; Boron Neutron Capture Therapy; Bromodeoxyuridine; Carcinoma, Squamous Cell; Isotopes; Mice; Micronucleus Tests; Organophosphorus Compounds; Sulfhydryl Compounds; Tumor Stem Cell Assay

Physiological differences between tumor and normal vasculature provide a target for drug discovery. In particular, the immature nature of tumor vasculature may render it intrinsically sensitive to disruption by agents affecting the endothelial cell cytoskeleton, including tubulin-binding agents. In this article, we report the synthesis of a water-soluble phosphate prodrug, ZD6126, of the tubulin-binding agent N-acetylcolchinol. In vitro studies demonstrate the comparative tubulin-binding properties of the prodrug and active drug, and show the induction of pronounced, reversible changes in endothelial cell morphology at subcytotoxic doses. Neither ZD6126 nor N-acetylcolchinol showed effects on the growth of human umbilical vein endothelial cells at concentrations below 100 micro M. In contrast, changes in endothelial cell morphology were seen at much lower, noncytotoxic concentrations (0.1 micro M) of ZD6126 and more pronounced effects were seen in proliferating versus confluent endothelial cell cultures. In vivo studies were carried out using a murine tumor model (CaNT) with single administration of a dose well below the maximum tolerated dose. These studies showed a large reduction in vascular volume, induction of extensive necrosis in tumors, and a reduced tumor cell yield in a clonal excision assay, consistent with vascular rather than cytotoxic effects. A viable rim of tumor remained after single-dose administration and minimal growth delay was observed. However, well-tolerated, multiple administration regimens led to pronounced tumor-growth delay. In the human xenograft FaDu, the growth delay given by a single dose of paclitaxel was enhanced by combination with a single dose of ZD6126, and the growth delay given by the combination was greater than the sum of the growth delays from the individual treatments. These findings show that ZD6126 is a promising antivascular agent for the treatment of solid tumors.

Topics: Adenocarcinoma; Angiogenesis Inhibitors; Animals; Carcinoma, Squamous Cell; Cattle; Cell Survival; Colchicine; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; Humans; Mammary Neoplasms, Experimental; Mice; Mice, Inbred CBA; Mice, SCID; Necrosis; Neoplasms, Experimental; Neovascularization, Pathologic; Organophosphorus Compounds; Pharyngeal Neoplasms; Prodrugs; Protein Binding; Tubulin; Xenograft Model Antitumor Assays