Measurement of PDT-induced hypoxia in Dunning prostate tumors by iodine-123-iodoazomycin arabinoside.
Photodynamic therapy (PDT) is known to produce vascular damage in solid tumors resulting in secondary ischemia and tumor cell death from hypoxia. The oxygenation status of both non-treated and PDT-treated Dunning R3327-AT prostate tumors growing in Fischer X Copenhagen rats was investigated with the novel hypoxic marker, 123I-iodoazomycin arabinoside (IAZA). Both qualitative and quantitative data from planar scintigraphy of anesthetized tumor-bearing rats showed increased retention of 123I-IAZA in tumors treated with PDT. Tumor perfusion in the same tumors was measured with 99mTc-hexamethylpropyleneamine oxime (HM-PAO). Region of interest analyses revealed an inverse correlation between tumor hypoxia measured by 123I-IAZA and tumor perfusion as measured by 99mTc-HMPAO (coefficient of correlation, r = -0.72). Planar images of 2-mm frozen sections from a large tumor showed 123I-IAZA selectively retained in the region that had been treated with PDT. This and other iodinated azomycin nucleosides, labeled with 123I, show promise for monitoring tumor oxygenation status non-invasively and, in particular, for monitoring the effectiveness of interstitial PDT treatments where perfusion shutdown is a major mechanism of tumor response.[1]References
- Measurement of PDT-induced hypoxia in Dunning prostate tumors by iodine-123-iodoazomycin arabinoside. Moore, R.B., Chapman, J.D., Mercer, J.R., Mannan, R.H., Wiebe, L.I., McEwan, A.J., McPhee, M.S. J. Nucl. Med. (1993) [Pubmed]
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