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Imaging of small-cell lung cancer xenografts with I-125, In-111, and Re-188 octreotides

Journal Article · · Journal of Nuclear Medicine
OSTI ID:441589
Somatostatin receptor imaging has been reported to be valuable for the localization of small-cell lung cancer (SCLC). We estimated the efficiency of I-125-Tyr-3-octreotide(I-125-octreotide), In-111-DTPA-D-Phe-1-octreotide (in-111-octreotide), and Re-188-octreotide in a mouse model of SCLC. Tyr-3-octreotide was labeled with I-125 by the chloramine T method, and In-111-octreotide was supplied by Mallinckrodt Medical (The Netherlands), while Re-188 was obtained from a W-188/Re-188 generator, and octreotide was labeled with Re-188 efficiently by a direct labeling using stannous chloride as a reduction agent. The expression of somatostatin receptor on NCI-H69 cells (a SCLC cell line) had been previously reported and we confirmed it by a cell binding assay. I-125-, In-111-, and Re-188-octreotides were injected i.v. into nude mice bearing NCI-H69 xenografts. Biodistributions were determined at 15 min, 2, 4, 8, and 24 h after injection. Specific binding of radiolabeled octreotides was observed by pretreatment of mice with unlabeled octreotide. Tumor uptake of I-125-, In-111-, and Re-188-octreotides at 2 h was 0.9{plus_minus}0.3, 0.3{plus_minus}0.1, 0.5{plus_minus}0.1% ID/g, respectively. Tumor-to-blood ratios were 0.91, 7.45, 0.41 at 2 h, 1.66, 11.16, 1.23 at 8 h for I-125-, In-111-, and Rej-188-octreotides, respectively. I-125-and Re-188 octreotides showed significant accumulations in the liver and GI tract. By contrast, In-111-octreotide cleared more rapidly from the blood and accumulated in normal tissues less than I-125- and Re-188- octreotides, resulting in high tumor-to-normal tissue ratios. In conclusion, as absolute level of tumor uptake of Re-188-octreotide is higher than that of In-111-octreotide, and Re-188-octreotide can be prepared easily as a kit, Re-188-octreotide is useful for the targeting of SCLC as well as I-125-octreotide, while In-111-octreotide is potent to achieve clear tumor-to-normal tissue contrast.
OSTI ID:
441589
Report Number(s):
CONF-950603--
Journal Information:
Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 36; ISSN JNMEAQ; ISSN 0161-5505
Country of Publication:
United States
Language:
English