UNLABELLED: When labeled with gamma-emitting radionuclides, somatostatin analogs have the potential to localize somatostatin receptor-positive tumors using gamma camera scintigraphy. We present a somatostatin analog, [DFO]-octreotide (SDZ 216-927), that comprises desferrioxamine B coupled to octreotide via a succinyl linker. This conjugate can be labeled with either 67Ga for gamma scintigraphy or 68Ga for PET imaging. The 67Ga-labeled conjugate is stable in vitro to autoradiolysis over a 24-hr period. METHODS: Rats bearing a somatostatin receptor-positive pancreatic islet cell tumor were injected with 20 MBq of 67Ga[DFO]-octreotide (33 GBq 67Ga/mumole). RESULTS: After 1 hr, the accumulation of 67Ga[DFO]-octreotide was 0.38 +/- 0.08 %ID/g and the tumor-to-nontumor ratios for blood, muscle, liver and intestine were 2.5, 7.4, 1.9 and 1.6, respectively. PET studies with 68Ga[DFO]-octreotide recorded a very rapid accumulation at the tumor and a subsequent residence half-life of about 6 hr. CONCLUSION: Gallium-68-[DFO]-octreotide can be used in PET studies to diagnose receptor-positive tumors such as gastroenteropancreatic, small-cell lung and breast tumors.
UNLABELLED: When labeled with gamma-emitting radionuclides, somatostatin analogs have the potential to localize somatostatin receptor-positive tumors using gamma camera scintigraphy. We present a somatostatin analog, [DFO]-octreotide (SDZ 216-927), that comprises desferrioxamine B coupled to octreotide via a succinyl linker. This conjugate can be labeled with either 67Ga for gamma scintigraphy or 68Ga for PET imaging. The 67Ga-labeled conjugate is stable in vitro to autoradiolysis over a 24-hr period. METHODS:Rats bearing a somatostatin receptor-positive pancreatic islet cell tumor were injected with 20 MBq of 67Ga[DFO]-octreotide (33 GBq 67Ga/mumole). RESULTS: After 1 hr, the accumulation of 67Ga[DFO]-octreotide was 0.38 +/- 0.08 %ID/g and the tumor-to-nontumor ratios for blood, muscle, liver and intestine were 2.5, 7.4, 1.9 and 1.6, respectively. PET studies with 68Ga[DFO]-octreotide recorded a very rapid accumulation at the tumor and a subsequent residence half-life of about 6 hr. CONCLUSION:Gallium-68-[DFO]-octreotide can be used in PET studies to diagnose receptor-positive tumors such as gastroenteropancreatic, small-cell lung and breast tumors.
Authors: Mila V Todorović-Tirnanić; Milan M Gajić; Vladimir B Obradović; Richard P Baum Journal: Cancer Biother Radiopharm Date: 2014-01-22 Impact factor: 3.099