Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer

<b>Background/Objectives:</b> Overexpressed in various solid tumors, the gastrin-releasing peptide receptor (GRPR) is a promising target for cancer diagnosis and therapy. However, the high pancreas uptake of the current clinically evaluated GRPR-targeted radiopharmaceuticals limits their...

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Main Authors: Lei Wang, Chao-Cheng Chen, Devon Chapple, Antonio A. W. L. Wong, Sara Kurkowska, Wing Sum Lau, Carlos F. Uribe, François Bénard, Kuo-Shyan Lin
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Published: MDPI AG 2025-02-01
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Online Access:https://www.mdpi.com/1424-8247/18/2/234
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author Lei Wang
Chao-Cheng Chen
Devon Chapple
Antonio A. W. L. Wong
Sara Kurkowska
Wing Sum Lau
Carlos F. Uribe
François Bénard
Kuo-Shyan Lin
author_facet Lei Wang
Chao-Cheng Chen
Devon Chapple
Antonio A. W. L. Wong
Sara Kurkowska
Wing Sum Lau
Carlos F. Uribe
François Bénard
Kuo-Shyan Lin
author_sort Lei Wang
collection DOAJ
description <b>Background/Objectives:</b> Overexpressed in various solid tumors, the gastrin-releasing peptide receptor (GRPR) is a promising target for cancer diagnosis and therapy. However, the high pancreas uptake of the current clinically evaluated GRPR-targeted radiopharmaceuticals limits their applications. In this study, we replaced the Pro<sup>14</sup> residue in our previously reported GRPR-targeted LW02056 and ProBOMB5 with 4,4-difluoroproline (diF-Pro) to obtain an agonist LW02060 (DOTA-Pip-[D-Phe<sup>6</sup>,Tle<sup>10</sup>,NMe-His<sup>12</sup>,diF-Pro<sup>14</sup>]Bombesin(6–14)) and an antagonist LW02080 (DOTA-Pip-[D-Phe<sup>6</sup>,NMe-Gly<sup>11</sup>,Leu<sup>13</sup>(ψ)diF-Pro<sup>14</sup>]Bombesin(6–14)), respectively. <b>Methods/Results</b>: The binding affinities (K<sub>i</sub>) of Ga-LW02060, Ga-LW02080, Lu-LW02060, and Lu-LW02080 were measured by in vitro competition binding assays using PC-3 cells and were found to be 5.57 ± 2.47, 21.7 ± 6.69, 8.00 ± 2.61, and 32.1 ± 8.14 nM, respectively. The <sup>68</sup>Ga- and <sup>177</sup>Lu-labeled ligands were obtained in 36–75% decay-corrected radiochemical yields with >95% radiochemical purity. PET imaging, SPECT imaging, and ex vivo biodistribution studies were conducted in PC-3 tumor-bearing mice. Both [<sup>68</sup>Ga]Ga-LW02060 and [<sup>68</sup>Ga]Ga-LW02080 enabled clear tumor visualization in PET images at 1 h post-injection (pi). Tumor uptake values of [<sup>68</sup>Ga]Ga-LW02060 and [<sup>68</sup>Ga]Ga-LW02080 at 1 h pi were 16.8 ± 2.70 and 7.36 ± 1.33 %ID/g, respectively, while their pancreas uptake values were 3.12 ± 0.89 and 0.38 ± 0.04 %ID/g, respectively. Compared to [<sup>177</sup>Lu]Lu-LW02080, [<sup>177</sup>Lu]Lu-LW02060 showed higher tumor uptake at all time points (1, 4, 24, 72, and 120 h pi). However, fast tumor clearance was observed for both [<sup>177</sup>Lu]Lu-LW02060 and [<sup>177</sup>Lu]Lu-LW02080. <b>Conclusions:</b> Our data demonstrate that [<sup>68</sup>Ga]Ga-LW02060 is promising for clinical translation for the detection of GRPR-expressing tumor lesions. However, further optimizations are needed for [<sup>177</sup>Lu]Lu-LW02060 and [<sup>177</sup>Lu]Lu-LW02080 to prolong tumor retention for therapeutic applications.
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spelling doaj-art-2fb6a0276a44426693ada8f608d3733d2025-08-20T02:45:01ZengMDPI AGPharmaceuticals1424-82472025-02-0118223410.3390/ph18020234Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing CancerLei Wang0Chao-Cheng Chen1Devon Chapple2Antonio A. W. L. Wong3Sara Kurkowska4Wing Sum Lau5Carlos F. Uribe6François Bénard7Kuo-Shyan Lin8Department of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Integrative Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Integrative Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, CanadaDepartment of Molecular Oncology, BC Cancer Research Institute, Vancouver, BC V5Z 1L3, Canada<b>Background/Objectives:</b> Overexpressed in various solid tumors, the gastrin-releasing peptide receptor (GRPR) is a promising target for cancer diagnosis and therapy. However, the high pancreas uptake of the current clinically evaluated GRPR-targeted radiopharmaceuticals limits their applications. In this study, we replaced the Pro<sup>14</sup> residue in our previously reported GRPR-targeted LW02056 and ProBOMB5 with 4,4-difluoroproline (diF-Pro) to obtain an agonist LW02060 (DOTA-Pip-[D-Phe<sup>6</sup>,Tle<sup>10</sup>,NMe-His<sup>12</sup>,diF-Pro<sup>14</sup>]Bombesin(6–14)) and an antagonist LW02080 (DOTA-Pip-[D-Phe<sup>6</sup>,NMe-Gly<sup>11</sup>,Leu<sup>13</sup>(ψ)diF-Pro<sup>14</sup>]Bombesin(6–14)), respectively. <b>Methods/Results</b>: The binding affinities (K<sub>i</sub>) of Ga-LW02060, Ga-LW02080, Lu-LW02060, and Lu-LW02080 were measured by in vitro competition binding assays using PC-3 cells and were found to be 5.57 ± 2.47, 21.7 ± 6.69, 8.00 ± 2.61, and 32.1 ± 8.14 nM, respectively. The <sup>68</sup>Ga- and <sup>177</sup>Lu-labeled ligands were obtained in 36–75% decay-corrected radiochemical yields with >95% radiochemical purity. PET imaging, SPECT imaging, and ex vivo biodistribution studies were conducted in PC-3 tumor-bearing mice. Both [<sup>68</sup>Ga]Ga-LW02060 and [<sup>68</sup>Ga]Ga-LW02080 enabled clear tumor visualization in PET images at 1 h post-injection (pi). Tumor uptake values of [<sup>68</sup>Ga]Ga-LW02060 and [<sup>68</sup>Ga]Ga-LW02080 at 1 h pi were 16.8 ± 2.70 and 7.36 ± 1.33 %ID/g, respectively, while their pancreas uptake values were 3.12 ± 0.89 and 0.38 ± 0.04 %ID/g, respectively. Compared to [<sup>177</sup>Lu]Lu-LW02080, [<sup>177</sup>Lu]Lu-LW02060 showed higher tumor uptake at all time points (1, 4, 24, 72, and 120 h pi). However, fast tumor clearance was observed for both [<sup>177</sup>Lu]Lu-LW02060 and [<sup>177</sup>Lu]Lu-LW02080. <b>Conclusions:</b> Our data demonstrate that [<sup>68</sup>Ga]Ga-LW02060 is promising for clinical translation for the detection of GRPR-expressing tumor lesions. However, further optimizations are needed for [<sup>177</sup>Lu]Lu-LW02060 and [<sup>177</sup>Lu]Lu-LW02080 to prolong tumor retention for therapeutic applications.https://www.mdpi.com/1424-8247/18/2/234gastrin-releasing peptide receptor4,4-difluoroprolinegallium-68lutetium-177pancreas uptake
spellingShingle Lei Wang
Chao-Cheng Chen
Devon Chapple
Antonio A. W. L. Wong
Sara Kurkowska
Wing Sum Lau
Carlos F. Uribe
François Bénard
Kuo-Shyan Lin
Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
Pharmaceuticals
gastrin-releasing peptide receptor
4,4-difluoroproline
gallium-68
lutetium-177
pancreas uptake
title Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
title_full Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
title_fullStr Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
title_full_unstemmed Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
title_short Synthesis and Evaluation of <sup>68</sup>Ga- and <sup>177</sup>Lu-Labeled [diF-Pro<sup>14</sup>]Bombesin(6−14) Analogs for Detection and Radioligand Therapy of Gastrin-Releasing Peptide Receptor-Expressing Cancer
title_sort synthesis and evaluation of sup 68 sup ga and sup 177 sup lu labeled dif pro sup 14 sup bombesin 6 14 analogs for detection and radioligand therapy of gastrin releasing peptide receptor expressing cancer
topic gastrin-releasing peptide receptor
4,4-difluoroproline
gallium-68
lutetium-177
pancreas uptake
url https://www.mdpi.com/1424-8247/18/2/234
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