Publisher: ROTOP Pharmaka GmbH, Bautzner Landstrasse 400, 01328 Dresden, Germany, Phone: +49 351 26 31 02 10, Fax: +49 351 26 31 03 13, e-mail: service@rotop-pharmaka.de
Pharmacotherapeutic group: Diagnostic radiopharmaceuticals, tumour detection, technetium (99mTc) compounds
ATC code: V09IA07
Technetium (99mTc) labelled EDDA/HYNIC-TOC binds with high affinity to somatostatin receptor subtypes 2 and 5, also to subtype 3 but with lesser affinity.
At the chemical concentrations used for diagnostic examinations 99mTcEDDA/HYNIC-TOC does not appear to have any pharmacodynamic activity.
Direct head-to-head comparison of technical performance (image quality and tumour/tissue uptake) and diagnostic performance (sensitivity and specificity) of technetium 99mTc-EDDA/HYNIC-TOC versus indium (111In) pentetreotide in the same patients and clinical contexts have not been provided in studies recruiting exclusively or mostly GEP-NET.
In the intended population of GEP-NET, three published studies assessed diagnostic performance of 99mTc-EDDA/HYNIC-TOC based on composite reference standards (histopathology or surgery or clinical imaging follow-up). In the study of Gomez et al. 2010, recruiting 32 patients with histologically proven or clinically suspected GEP-NET (22 carcinoid, 2 insulinomas, 2 gastrinomas and 6 non-specific), sensitivity and specificity were 94% (16/17) and 100% (15/15), respectively, for detection of primary tumour and 79% (11/14) and 100% (18/18), respectively, for detection of metastases. Sepulveda et al. 2012 with 56 patients with suspected neuroendocrine tumours, mostly GEP-NET, undergoing scintigraphy with 99mTc-EDDA/HYNIC-TOC for detection of primary tumour or metastases obtained a sensitivity and specificity of 88.4% (78-97%) and 92.3% (64-100%), respectively. In the study of Gabriel et al. 2005, scintigraphy with 99mTc-EDDA/HYNIC-TOC performed in 88 proven GEPNET resulted in a sensitivity of 77.5% (31/40) and specificity of 50% (½) for initial staging, and of 83.3% (25/30) and 100% (16/16), respectively, for restaging
After intravenous administration, 99mTc-EDDA/HYNIC-TOC is rapidly eliminated from the blood. Already after 10 minutes, accumulation of the 99mTc-EDDA/HYNICTOC is seen in the main organs, i.e. liver, spleen and kidneys as well as in tumours expressing somatostatin receptors.
Maximal values of the tumour/background ratio are observed at 4 hours after injection. Cancer lesions are still visible after 24 hours. Slight excretion by the alimentary tract is observed in late images.
The activity is excreted mainly by the renal route with a small contribution of hepatic excretion. 99mTc-EDDA/HYNIC-TOC is rapidly eliminated from the blood. The activity accumulated in the blood cells is below 5% regardless of time after injection.
In studies performed in mice and rats no effects of acute toxicity at dose level of 40 µg/kg bodyweight have been found. Toxicity with repeated administration of 99mTc-EDDA/HYNIC-TOC was not tested. This agent is not intended for regular or continuous administration.
Mutagenicity studies performed in a bacterial reverse mutation assay showed no 99mTc-EDDA/HYNIC-TOC induced gene mutations.
Long-term carcinogenicity studies have not been carried out.
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