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Glioma
Research from Purdue University provides new data on glioma
November 5th, 2009
Research findings, '99mTcO(MAG2-3G3-dimer): a new integrin alpha vbeta3-targeted SPECT radiotracer with high tumor uptake and favorable pharmacokinetics,' are discussed in a new report. "This report presents the synthesis of a cyclic RGD dimer conjugate, MAG(2)-G(3)-E[G(3)-c(RGDfK)](2) (MAG(2)-3G(3)-dimer, G(3)=Gly-Gly-Gly, MAG(2)=S-benzoyl mercaptoacetylglycylglycyl), and evaluation of its (99m)Tc complex, (99m)TcO(MAG(2)-3G(3)-dimer), as a new radiotracer for imaging the tumor integrin alpha(v)beta(3) expression. An in vitro displacement assay was used to determine the integrin alpha(v)beta(3) binding affinity of MAG(2)-3G(3)-dimer against (125)I-c(RGDyK) bound to U87MG human glioma cells," scientists in the United States report. "The athymic nude mice bearing U87MG glioma xenografts were used for biodistribution and planar imaging studies. We found that (1) MAG(2) is such a highly effective bifunctional chelator that (99m)TcO(MAG(2)-3G(3)-dimer) can be prepared in high yield (radiochemical purity >95%) and with high specific activity (approximately 5 Ci/micromol) using a kit formulation; (2) (99m)TcO(MAG(2)-3G(3)-dimer) has very high solution stability in the kit matrix; and (3) (99m)TcO(MAG(2)-3G(3)-dimer) has very fast clearance kinetics from the intestine, liver, and kidneys. Among the (99m)Tc-labeled cyclic RGD peptides evaluated in the xenografted U87MG glioma models, (99m)TcO(MAG(2)-3G(3)-dimer) has the best pharmacokinetics and tumor to background ratios (tumor/liver=4.29 +/-1.00 at 30 min postinjection and 8.29 +/-1.50 at 120 min postinjection; tumor/kidney=1.16 +/-0.19 at 30 min postinjection and 2.49 +/-0.25 at 120 min postinjection). Planar imaging studies showed that tumors in the glioma-bearing mice administered with (99m)TcO(MAG(2)-3G(3)-dimer) can be visualized with excellent contrast as early as 15 min postinjection. (99m)TcO(MAG(2)-3G(3)-dimer) was able to maintain its chemical integrity in kidneys (>80% intact) and liver (>95% intact) over the 2-h period. However, there was significant metabolism (>50% of the injected radioactivity) detected in both urine and feces samples," wrote J. Shi and colleagues, Purdue University. The researchers concluded: "(99m)TcO(MAG(2)-3G(3)-dimer) is a very attractive radiotracer for early detection of integrin alpha(v)beta(3)-positive tumors and has significant advantages over the (18)F-labeled RGD peptide radiotracers with respect to the cost, availability, and easiness for routine clinical preparation." Shi and colleagues published their study in European Journal of Nuclear Medicine and Molecular Imaging (99mTcO(MAG2-3G3-dimer): a new integrin alpha vbeta3-targeted SPECT radiotracer with high tumor uptake and favorable pharmacokinetics. European Journal of Nuclear Medicine and Molecular Imaging, 2009;36(11):1874-84). For more information, contact J. Shi, School of Health Sciences, Purdue University, West Lafayette, IN 47907 USA.. Publisher contact information for the European Journal of Nuclear Medicine and Molecular Imaging is: Springer, 233 Spring Street, New York, NY 10013, USA. Keywords: United States, West Lafayette, Biotechnology, Drugs, Glioma, Nuclear Medicine, Oncology, Pharmaceuticals, Pharmacokinetics, Therapies, Xenograft, Xenotransplantion. This article was prepared by NewsRx editors from staff and other reports. Copyright 2009, NewsRx.com.
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