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Kwon D, Zhang Z, Zeisler J, Kuo HT, Lin KS, Benard F. Reducing the Kidney Uptake of High Contrast CXCR4 PET Imaging Agents via Linker Modifications. Pharmaceutics 2022; 14:pharmaceutics14071502. [PMID: 35890397 PMCID: PMC9316317 DOI: 10.3390/pharmaceutics14071502] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/02/2022] [Accepted: 07/07/2022] [Indexed: 01/27/2023] Open
Abstract
Purpose: The C-X-C chemokine receptor 4 (CXCR4) is highly expressed in many subtypes of cancers, notably in several kidney-based malignancies. We synthesized, labeled, and assessed a series of radiotracers based on a previous high contrast PET imaging radiopharmaceutical [68Ga]Ga-BL02, with modifications to its linker and metal chelator, in order to improve its tumor-to-kidney contrast ratio. Methods: Based on the design of BL02, a piperidine-based cationic linker (BL06) and several anionic linkers (tri-Aad (BL17); tri-D-Glu (BL20); tri-Asp (BL25); and tri-cysteic acid (BL31)) were substituted for the triglutamate linker. Additionally, the DOTA chelator was swapped for a DOTAGA chelator (BL30). Each radiotracer was labeled with 68Ga and evaluated in CXCR4-expressing Daudi xenograft mice with biodistribution and/or PET imaging studies. Results: Of all the evaluated radiotracers, [68Ga]Ga-BL31 showed the most promising biodistribution profile, with a lower kidney uptake compared to [68Ga]Ga-BL02, while retaining the high imaging contrast capabilities of [68Ga]Ga-BL02. [68Ga]Ga-BL31 also compared favorably to [68Ga]Ga-Pentixafor, with superior imaging contrast in all non-target organs. The other anionic linker-based radiotracers showed either equivocal or worse contrast ratios compared to [68Ga]Ga-BL02; however, [68Ga]Ga-BL25 also showed lower kidney uptake, as compared to that of [68Ga]Ga-BL02. Meanwhile, [68Ga]Ga-BL06 had high non-target organ uptake and relatively lower tumor uptake, while [68Ga]Ga-BL30 showed significantly increased kidney uptake and similar tumor uptake values. Conclusions: [68Ga]Ga-BL31 is an optimized CXCR4-targeting radiopharmaceutical with lower kidney retention that has clinical potential for PET imaging and radioligand therapy.
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Affiliation(s)
- Daniel Kwon
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
| | - Zhengxing Zhang
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
| | - Jutta Zeisler
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
| | - Hsiou-Ting Kuo
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
| | - Kuo-Shyan Lin
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
- Department of Radiology, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Francois Benard
- Department of Molecular Oncology, BC Cancer, Vancouver, BC V5Z 1L3, Canada; (D.K.); (Z.Z.); (J.Z.); (H.-T.K.); (K.-S.L.)
- Department of Radiology, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
- Correspondence: ; Tel.: +1-604-675-8206
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