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Busslinger SD, Becker AE, Vaccarin C, Deberle LM, Renz ML, Groehn V, Schibli R, Müller C. Investigations Using Albumin Binders to Modify the Tissue Distribution Profile of Radiopharmaceuticals Exemplified with Folate Radioconjugates. Cancers (Basel) 2023; 15:4259. [PMID: 37686538 PMCID: PMC10486429 DOI: 10.3390/cancers15174259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/14/2023] [Accepted: 08/19/2023] [Indexed: 09/10/2023] Open
Abstract
Introducing an albumin-binding entity into otherwise short-lived radiopharmaceuticals can be an effective means to improve their pharmacokinetic properties due to enhanced blood residence time. In the current study, DOTA-derivatized albumin binders based on 4-(p-iodophenyl)butanoate (DOTA-ALB-1 and DOTA-ALB-3) and 5-(p-iodophenyl)pentanoate entities (DOTA-ALB-24 and DOTA-ALB-25) without and with a hydrophobic 4-(aminomethyl)benzoic acid (AMBA) linker unit, respectively, were synthesized and labeled with lutetium-177 for in vitro and in vivo comparison. Overall, [177Lu]Lu-DOTA-ALB-1 demonstrated ~3-fold stronger in vitro albumin-binding affinity and a longer blood residence time (T50%IA ~8 h) than [177Lu]Lu-DOTA-ALB-24 (T50%IA ~0.8 h). Introducing an AMBA linker enhanced the albumin-binding affinity, resulting in a T50%IA of ~24 h for [177Lu]Lu-DOTA-ALB-3 and ~2 h for [177Lu]Lu-DOTA-ALB-25. The same albumin binders without or with the AMBA linker were incorporated into 6R- and 6S-5-methyltetrahydrofolate-based DOTA-conjugates (177Lu-RedFols). Biodistribution studies in mice performed with both diastereoisomers of [177Lu]Lu-RedFol-1 and [177Lu]Lu-RedFol-3, which comprised the 4-(p-iodophenyl)butanoate moiety, demonstrated a slower accumulation in KB tumors than those of [177Lu]Lu-RedFol-24 and [177Lu]Lu-RedFol-25 with the 5-(p-iodophenyl)pentanoate entity. In all cases, the tumor uptake was high (30-45% IA/g) 24 h after injection. Both diastereoisomers of [177Lu]Lu-RedFol-1 and [177Lu]Lu-RedFol-3 demonstrated high blood retention (3.8-8.7% IA/g, 24 h p.i.) and a 2- to 4-fold lower kidney uptake than the corresponding diastereoisomers of [177Lu]Lu-RedFol-24 and [177Lu]Lu-RedFol-25, which were more rapidly cleared from the blood (<0.2% IA/g, 24 h after injection). Kidney retention of the 6S-diastereoisomers of all 177Lu-RedFols was consistently higher than that of the respective 6R-diastereoisomers, irrespective of the albumin binder and linker unit used. It was demonstrated that the blood clearance data obtained with 177Lu-DOTA-ALBs had predictive value for the blood retention times of the respective folate radioconjugates. The use of these albumin-binding entities without or with an AMBA linker may serve for fine-tuning the blood retention of folate radioconjugates and also other radiopharmaceuticals and, hence, optimize their tissue distribution profiles. Dosimetry estimations based on patient data obtained with one of the most promising folate radioconjugates will be crucial to identify the dose-limiting organ, which will allow for selecting the most suitable folate radioconjugate for therapeutic purposes.
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Affiliation(s)
- Sarah D. Busslinger
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
| | - Anna E. Becker
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
| | - Christian Vaccarin
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
| | - Luisa M. Deberle
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
| | - Marie-Luise Renz
- Merck & Cie KmG, Im Laternenacker 5, 8200 Schaffhausen, Switzerland; (M.-L.R.); (V.G.)
| | - Viola Groehn
- Merck & Cie KmG, Im Laternenacker 5, 8200 Schaffhausen, Switzerland; (M.-L.R.); (V.G.)
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
| | - Cristina Müller
- Center for Radiopharmaceutical Sciences ETH-PSI, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen-PSI, Switzerland; (S.D.B.); (A.E.B.); (C.V.); (L.M.D.); (R.S.)
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
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Folate-based radiotracers for nuclear imaging and radionuclide therapy. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Benešová M, Guzik P, Deberle LM, Busslinger SD, Landolt T, Schibli R, Müller C. Design and Evaluation of Novel Albumin-Binding Folate Radioconjugates: Systematic Approach of Varying the Linker Entities. Mol Pharm 2022; 19:963-973. [PMID: 35192367 DOI: 10.1021/acs.molpharmaceut.1c00932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tumor targeting using folate radioconjugates is a promising strategy for theragnostics of folate receptor-positive tumors. The aim of this study was to investigate the impact of structural modifications of folate radioconjugates on their pharmacokinetic properties. Four novel folate radioconjugates ([177Lu]Lu-OxFol-2, [177Lu]Lu-OxFol-3, [177Lu]Lu-OxFol-4, and [177Lu]Lu-OxFol-5), modified with a lipophilic or hydrophilic linker entity in close proximity to the albumin-binding 4-(p-iodophenyl)butanoate entity or the DOTA chelator, respectively, were designed and evaluated for comparison with the previously developed [177Lu]Lu-OxFol-1. A hydrophobic 4-(aminomethyl)benzoic acid linker, incorporated in close proximity to the 4-(p-iodophenyl)butanoate entity, enhanced the albumin-binding properties (relative affinity 7.3) of [177Lu]Lu-OxFol-3 as compared to those of [177Lu]Lu-OxFol-1 (relative affinity set as 1.0). On the other hand, a hydrophilic d-glutamic acid (d-Glu) linker entity used in [177Lu]Lu-OxFol-2 compromised the albumin-binding properties. [177Lu]Lu-OxFol-4 and [177Lu]Lu-OxFol-5, in which the respective linker entities were incorporated adjacent to the DOTA chelator, showed similar albumin-binding properties (0.6 and 1.0, respectively) as [177Lu]Lu-OxFol-1. Biodistribution studies in KB tumor-bearing nude mice revealed twofold higher tumor-to-kidney ratios at 4 h and 24 h after injection of [177Lu]Lu-OxFol-3 (∼1.2) than after injection of [177Lu]Lu-OxFol-1 (∼0.6). The tumor-to-kidney ratios of [177Lu]Lu-OxFol-2 were, however, much lower (∼0.2) due to the high kidney retention of this radioconjugate. The tumor-to-kidney ratios of [177Lu]Lu-OxFol-5 were only slightly increased (∼0.9), and the ratios for [177Lu]Lu-OxFol-4 (∼0.7) were in the same range as for [177Lu]Lu-OxFol-1. SPECT/CT imaging studies demonstrated similar tumor uptake of all radioconjugates but a clearly improved tumor-to-kidney ratio for [177Lu]Lu-OxFol-3 as compared to that for [177Lu]Lu-OxFol-1. Based on these data, it can be concluded that the linker entity in close proximity to the 4-(p-iodophenyl)butanoate entity affects the radioconjugate's pharmacokinetic profile considerably due to the altered affinity to albumin. Changes in the linker entity, which connects the DOTA chelator with the folate molecule, do not have a major impact on the radioconjugate's tissue distribution profile, however. As a result of these findings, [177Lu]Lu-OxFol-3 had a comparable therapeutic effect to that of [177Lu]Lu-OxFol-1 but appeared advantageous in preventing kidney damage. Provided that the kidneys will present the dose-limiting organs in patients, [177Lu]Lu-OxFol-3 would be the preferred candidate for a clinical translation.
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Affiliation(s)
- Martina Benešová
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland.,Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
| | - Patrycja Guzik
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Luisa M Deberle
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Sarah D Busslinger
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Tanja Landolt
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland.,Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
| | - Cristina Müller
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland.,Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
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