Does the Use of Protease Inhibitors Further Improve in Vivo Distribution?
Targeting of the Cholecystokinin-2 Receptor with the Minigastrin Analog 177Lu-DOTA-PP-F11N: Does the Use of Protease Inhibitors Further Improve In Vivo Distribution? Alexander W. Sauter*1,2, Rosalba Mansi*3, Ulrich Hassiepen4, Lionel Muller4, Tania Panigada4, Stefan Wiehr2, Anna-Maria Wild2, Susanne Geistlich5, Martin B´eh´e5, Christof Rottenburger1, Damian Wild1, and Melpomeni Fani3 1Division of Nuclear Medicine, University Hospital Basel, Basel, Switzerland; 2Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, Tuebingen, Germany; 3Division of Radiopharmaceutical Chemistry, University Hospital Basel, Basel, Switzerland; 4Novartis Pharma AG, Institutes for Biomedical Research, Novartis Campus, Basel, Switzerland; and 5Center for Radiopharmaceutical Sciences, Paul Scherrer Institute, Villigen, Switzerland performance of 177Lu-DOTA-MG11 in the presence of inhibitors. The Patients with metastatic medullary thyroid cancer (MTC) have limited human application of single compounds without unessential additives systemic treatment options. The use of radiolabeled gastrin analogs is preferable. Preliminary clinical data spotlight the stomach as a po- targeting the cholecystokinin-2 receptor (CCK2R) is an attractive tential dose-limiting organ besides the kidneys. approach. However, their therapeutic efficacy is presumably decreased Key Words: medullary thyroid cancer; cholecystokinin-2 receptor; by their enzymatic degradation in vivo. We aimed to investigate whether gastrin; peptide receptor radionuclide therapy; 177Lu-DOTA-PP-F11N 177 177 the chemically stabilized analog Lu-DOTA-PP-F11N ( Lu-DOTA- J Nucl Med 2019; 60:393–399 (DGlu)6-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2) performs better than refer- DOI: 10.2967/jnumed.118.207845 ence analogs with varying in vivo stability, namely 177Lu-DOTA-MG11 177 177 ( Lu-DOTA-DGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2)and Lu-DOTA- 177 PP-F11 ( Lu-DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2), and whether the use of protease inhibitors further improves CCKR2 targeting.
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