technetium-tc-99m-depreotide and Disease-Models--Animal

(177)Lu-DOTA-Tyr(3)-octreotate is a candidate radiopharmaceutical for the therapy of somatostatin receptor (sstr)-positive small cell lung cancer (SCLC). Scintigraphy of lung tumors is made with 2 alternative somatostatin analogs, (111)In-DTPA-octreotide or (99m)Tc-depreotide. The aim of this study was to compare the biodistribution of these 3 radiopharmaceuticals in SCLC xenografted to nude mice.. Nude mice, bearing tumors from the human SCLC cell line NCI-H69, were intravenously injected with 10 MBq (2.4 microg) (99m)Tc-depreotide and 2 MBq (0.5 microg) (111)In-DTPA-octreotide simultaneously. The activity concentration (%IA/g) was measured in tumor and normal tissue at 2, 4, and 24 hours postinjection (hpi). The results were compared with earlier published biodistribution data of 3 MBq (0.7 microg) (177)Lu-DOTA-Tyr(3)-octreotate in the same animal model.. The activity concentration of (111)In-DTPAoctreotide in tumor was higher than the activity concentration of (99m)Tc-depreotide at 2-24 hpi, p < 0.05. The highest tumor uptake at 24 hpi was, however, found for (177)Lu-DOTA-Tyr(3)-octreotate. The activity concentration of (99m)Tc-depreotide was significantly higher in the heart, lungs, liver, the salivary glands, spleen, and bone marrow than for (111)In-DTPA-octreotide at 2-24 hpi. Saturation of the somatostatin receptors may have influenced the uptake in tumor and sstr-positive normal tissues.. The low tumor-to-lung and tumor-to-liver activity concentration ratios for (99m)Tc-depreotide could result in a lower detection rate of SCLC with this compound versus (111)In-DTPA-octreotide. (177)Lu-DOTA-Tyr(3)-octreotate gave the highest tumor-activity concentration, and has, thus, the best properties for therapy.

Topics: Animals; Carcinoma, Small Cell; Cell Line, Tumor; Disease Models, Animal; Humans; Indium Radioisotopes; Liver; Lung; Lung Neoplasms; Mice; Mice, Nude; Neoplasm Transplantation; Neoplasms, Experimental; Octreotide; Organometallic Compounds; Organotechnetium Compounds; Pentetic Acid; Radiopharmaceuticals; Somatostatin; Time Factors; Tissue Distribution