Improved kit formulation for preparation of (99m)Tc-HYNIC-TOC: results of preliminary clinical evaluation in imaging patients with neuroendocrine tumors.

Abstract

(99m)Tc-HYNIC-TOC is a cost-effective and logistically viable agent for scintigraphy of neuroendocrine tumors overexpressing somatostatin receptors as compared with [(111)In-DTPA-D-Phe(1)] Octreotide (Octreoscan(®)). Several studies have been reported, wherein the efficacy of this agent is demonstrated. In the present article, the authors report the preparation of a single-vial HYNIC-TOC kit suitable for the preparation of 4-5 patient doses (15 mCi/patient) of (99m)Tc-HYNIC-TOC. The kits were tested for sterility and bacterial endotoxins to assure safety of the product. A significant modification in this kit is the inclusion of buffer in the kit itself, unlike in commercially available kits where the buffer solution has to be added during preparation. (99m)Tc-HYNIC-TOC was prepared by adding 20-80 mCi (740-2960 MBq) of freshly eluted Na(99m)TcO4 in 1-3 mL of sterile saline directly into the kit vial and heating the vial in a water bath at 100°C for 20 minutes. The labeling yield and radiochemical purity of (99m)Tc-HYNIC-TOC, prepared using the lyophilized cold kit, were consistently >90%. The kits were evaluated over a period of 9 months and found to be stable when stored at -20°C. Limited clinical studies performed with the (99m)Tc-HYNIC-TOC, formulated using the kit, showed adequate sensitivity and specificity for the detection of gasteroenteropancreatic neuroendocrine tumors.