The long term objectives of this program is to investigate in mouse and man the characteristics of tumor physiology which will determine the effectiveness of 'bioreductive radiation therapy' (defined as the combination of fractionated irradiation with multiple doses of a hypoxic cytotoxin), and to ascertain to what extent this therapy can be improved by manipulations of the tumor physiology. Adding to radiation therapy a drug that selectively kills hypoxic cells is potentially applicable to all solid tumors containing hypoxic cells, irrespective of whether these hypoxic cells limit the efficacy of standard radiation fractionation. Theoretically, the presence of hypoxic cells should render the tumors considerable more susceptible to radiation therapy than if all of the tumor cells were well oxygenated, provided the hypoxic cytotoxin can be given repeatedly, preferably with each radiation dose. In other words, the presence of hypoxic cells in solid tumors can be an advantage in cancer treatment by radiotherapy. One of the most hypoxic- selective bioreductive drugs known to date, the benzotriazine di-N-oxide, SR 4233, is about to enter clinical trails and will be used with as many radiation doses as possible in a typical radiotherapy regimen. However, the extent to which this therapy can exploit hypoxic cells in radiotherapy depends on key assumptions of the physiology of tumors. A major goal of this application is to test these assumptions in a selection of transplanted murine tumors and human tumor xenografts. In these tumors, the kinetics both of rehypoxiation following a single dose of SR 4233 and of reoxygenation following a single X-ray dose will be measured and compared. The extent to which the kinetics of these two processes are similar will provide important evidence on the underlying mechanism of these two processes. Since the efficacy of bioreductive radiation therapy should depend on the level of tumor hypoxia, various methods to measure tumor hypoxia and to follow it during therapy will be employed. These will include radiobiological assays. 14C-misonidazole binding and oxygen tension measurements using a computerized polarographic electrode. In addition to the work with animal tumors, oxygen tension measurements in human tumors before and during therapy will be monitored using the same polarographic oxygen electrode system (pO2 histography) used with the mouse tumors. The possibility of increasing the efficacy of bioreductive therapy by manipulating the tumor physiology to increase tumor hypoxia will also be investigated. These manipulations will include reducing inspired O2 levels to 10% and 15%, using the agent BW12C which increased oxygen bonding to hemoglobin and using the cytokine interleukin 1. These manipulations have been chosen as likely to produce some--not necessarily a large--increase in the hypoxia of human tumors when given repeatedly following irradiation.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA025990-16
Application #
2330682
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1979-08-01
Project End
1998-01-31
Budget Start
1997-02-10
Budget End
1998-01-31
Support Year
16
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Stanford University
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
800771545
City
Stanford
State
CA
Country
United States
Zip Code
94305
Brown, Martin (2010) Henry S. Kaplan Distinguished Scientist Award Lecture 2007. The remarkable yin and yang of tumour hypoxia. Int J Radiat Biol 86:907-17
Sasai, K; Brown, J M (1994) Discrepancies between measured changes of radiobiological hypoxic fraction and oxygen tension monitoring using two assay systems. Int J Radiat Oncol Biol Phys 30:355-61
Kim, I H; Brown, J M (1994) Reoxygenation and rehypoxiation in the SCCVII mouse tumor. Int J Radiat Oncol Biol Phys 29:493-7
Brown, J M; Giaccia, A J (1994) Tumour hypoxia: the picture has changed in the 1990s. Int J Radiat Biol 65:95-102
Horsman, M R; Chaplin, D J (1994) Enhancement of cyclophosphamide cytotoxicity in vivo by the benzamide analogue pyrazinamide. Br J Cancer 69:648-54
Kim, I H; Lemmon, M J; Brown, J M (1993) The influence of irradiation of the tumor bed on tumor hypoxia: measurements by radiation response, oxygen electrodes, and nitroimidazole binding. Radiat Res 135:411-7
Minchinton, A I; Brown, J M (1992) Enhancement of the cytotoxicity of SR 4233 to normal and malignant tissues by hypoxic breathing. Br J Cancer 66:1053-8
Stone, H B; Minchinton, A I; Lemmon, M et al. (1992) Pharmacological modification of tumor blood flow: lack of correlation between alteration of mean arterial blood pressure and changes in tumor perfusion. Int J Radiat Oncol Biol Phys 22:79-86
Koong, A C; Hirst, D G (1991) The influence of chronic anaemia on the radiosensitivity of two mouse tumours. Br J Cancer 63:499-502
Stone, H B; Hirst, V K; Cribbs, R et al. (1991) A comparison of radiosensitization by etanidazole and pimonidazole in mouse tumors. Int J Radiat Oncol Biol Phys 20:987-95

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