Improved Kit Formulation for Preparation of 99m Tc-HYNIC-TOC: Results of Preliminary Clinical Evaluation in Imaging Patients with Neuroendocrine Tumors

Abstract

^99mTc-HYNIC-TOC is a cost-effective and logistically viable agent for scintigraphy of neuroendocrine tumors overexpressing somatostatin receptors as compared with [¹¹¹In-DTPA-D-Phe¹] 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 ^99mTc-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. ^99mTc-HYNIC-TOC was prepared by adding 20–80 mCi (740–2960 MBq) of freshly eluted Na^99mTcO₄ 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 ^99mTc-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 ^99mTc-HYNIC-TOC, formulated using the kit, showed adequate sensitivity and specificity for the detection of gasteroenteropancreatic neuroendocrine tumors.