The Effect of Pentoxifylline in Improving Tumor Hypoxia Assessed by (superscript 99m)Tc-HL91-NI

Purpose: (superscript 99m)Tc-HL-NI is a novel hypoxia-imaging agent synthesized by the Institute of Nuclear Energy Research (INER). Pentoxifylline (PTX) is a peripheral vasodilator and has been found to improve tumor hypoxia and to enhance response to radiotherapy. The purpose of the study was to evaluate the feasibility of using (superscript 99m)Tc-HL91-NI for assessing the effect of PTX in modifying tumor hypoxia. Methods: The human breast cancer-bearing nude mice were pretreated with 100 mg of PTX as the study group. (superscript 99m)Tc-HL91-NI was administered intravenously and whole body scan was performed at 2 h post-injection. The uptake ratios of tumor-to-background (T/B) were measured. Parallel studies without PTX pretreatment were performed as control group for comparison. Results: There was relatively higher uptake of (superscript 99m)Tc-HL91-NI in tumor compared to the contralateral thigh. In addition, the tumor uptake of (superscript 99m)Tc-HL91-NI was significantly reduced in PTX treated group than controls. The T/B ratios of (superscript 99m)Tc-HL91-NI were 1.95±0.34 and 3.53±0.55 for PTX and control groups, respectively (P=0.01). Conclusions: The preliminary results suggested that (superscript 99m)Tc-HL91-NI prepared by INER could be used to noninvasively evaluate the effect of PTX in improving tumor hypoxia in vivo. Further human trials should be warranted before its clinical applications.