Combination of the vascular targeting agent ZD6126 with boron neutron capture therapy
- Radiation Oncology Research Laboratory, Research Reactor Institute, Kyoto University, Osaka (Japan)
- Division of Radiation Life Science, Research Reactor Institute, Kyoto University, Osaka (Japan)
- Division of Radiation Safety, Research Reactor Institute, Kyoto University, Osaka (Japan)
Purpose: 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). Methods and materials: Sodium borocaptate-{sup 10}B (BSH, 125 mg/kg, i.p.) or l-p-boronophenylalanine-{sup 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 {sup 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 {sup 10}B-carrier and ZD6126 in the same manner as the above-mentioned {sup 10}B pharmacokinetics analyses. To obtain almost similar intratumor {sup 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. Results: Pharmacokinetics analyses showed that combination with ZD6126 greatly increased the {sup 10}B concentrations in tumors after 60 min after BSH injection and after 120 min after BPA injection. The concentrations of {sup 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 {sup 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 {sup 10}B-carrier. Conclusions: 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 {sup 10}B-carrier for BNCT.
- OSTI ID:
- 20630945
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 60, Issue 3; Other Information: DOI: 10.1016/j.ijrobp.2004.07.672; PII: S0360-3016(04)02009-7; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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