ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P41. Preclinical Evaluation of New Radiolabeled CCK Ligands as
Molecular Imaging Agents for CCK2 Receptor Targeting
S. Dorbes a , S. Brillouet b , L.P. Delord c , F. Courbon b , M. Poirot a , S. Silvente-Poirot a
a
Métabolisme, oncogénèse et différenciation cel, Institut Claudius Regaud, 20-24 rue du pont Saint-Pierre
31059, Toulouse, France
e-mail: dorbes@chimie.ups-tlse.fr
b
Département de Service de Médecine Nucléaire, Institut Claudius Regaud, 20-24 rue du pont Saint-Pierre,
31059, Toulouse, France
c
EA3035 Laboratoire de Pharmacologie Clinique et Ex, Institut Claudius Regaud, 20-24 rue du pont Saint-
Pierre, 31059, Toulouse, France
Somatostatin receptor scintigraphy has been proven as a valuable tool for staging gastrointestinal endocrine
tumors. But, its sensitivity and accuracy in other cancers, such as metastatic medullary thyroid cancer (MTC), is
limited. Actually, either the somatostatin receptors are not expressed in these tumors and metastasis or their
expression change during the evolution of the pathology.
The cholecystokinin/gastrin receptor (CCK2R) is overexpressed in MTC up to 90% but not in the corresponding
healthy tissues [1]. Thus, the CCK2R represents a potential target for the diagnosis and internal radiotherapy of
these tumors. Previously studies had demonstrated the feasibility of radiolabeled CCK/gastrin ligands to target
MTC in animals and patients. Different adverse effects using these radioligands were reported indicating that
tumor uptake, biodistribution and stability of the radioligand must be improved for clinical application[2].
The aim of this study was to synthesise new radioligands of the CCK2R with optimized properties to target the
CCK2R in different tumor models : E151A-CCK2R-NIH-3T3 [3] and TT (MTC) cells.
Chemical synthesis, EC50 studies, SPECT (Single Photon Emission Computed Tomography) imaging and
biodistribution of optimized CCK2R radioligands will be presented in this communication.
References:
[1] J. C. Reubi, J. C. Schaer, Cancer Res., 57, 1377 (1997).
[2] M. Béhé, T. Behr, Biopolymers (Pept. Sci.), 66, 399 (2002).
[3] C. Gales et al, Oncogene, 22, 6081 (2003).
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