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Huynh TT, Feng Y, Meshaw R, Zhao XG, Rosenfeld L, Vaidyanathan G, Papo N, Zalutsky MR. PSMA-reactive NB7 single domain antibody fragment: A potential scaffold for developing prostate cancer theranostics. Nucl Med Biol 2024; 134-135:108913. [PMID: 38703588 DOI: 10.1016/j.nucmedbio.2024.108913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/29/2024] [Accepted: 04/22/2024] [Indexed: 05/06/2024]
Abstract
INTRODUCTION Single domain antibody fragments (sdAbs) are an appealing scaffold for radiopharmaceutical development due to their small size (~15 kDa), high solubility, high stability, and excellent tumor penetration. Previously, we developed NB7 sdAb, which has very high affinity for an epitope on PSMA that is different from those targeted by small molecule PSMA inhibitors. Herein, we evaluated NB7 after radioiodination using [*I]SGMIB (1,3,4-isomer) and iso-[*I]SGMIB (1,3,5-isomer), as well as their 211At-labeled analogues. METHODS [*I]SGMIB, iso-[*I]SGMIB, [211At]SAGMB, and iso-[211At]SAGMB conjugates of NB7 sdAb were synthesized and their binding affinity, cell uptake and internalization were assessed in PSMA+ PC3 PIP and PSMA- PC3 flu cells. Biodistribution studies were performed in mice bearing PSMA+ PC3 PIP xenografts. First, a single-label experiment evaluated the tissue distribution of a NB7 bearing a His6-tag (NB7H6) and labeled with iso-[125I]SGMIB. Three paired-label experiments then were performed to compare: a) NB7 labeled using [*I]SGMIB and iso-[*I]SGMIB, b) 131I- vs 211At-labeled NB7 conjugates and c) [125I]SGMIB-NB7H6 to the small molecule PSMA inhibitor [131I]YF2. RESULTS All NB7 radioconjugates bound specifically to PSMA with dissociation constants, Kd, in the low nM range (1.4-6.4 nM). An initial biodistribution study demonstrated good tumor uptake for iso-[125I]SGMIB-NB7H6 (7.2 ± 1.5 % ID/g at 1 h) and no deleterious effect of the His6-tag on renal activity levels, which declined to 3.1 ± 1.1 % ID/g by 4 h. Paired-label biodistribution found no distinction between the two SGMIB isomer NB7 conjugates with the [131I]SGMIB-NB7-to-iso-[125I]SGMIB-NB7 tumor uptake ratios not significantly different from unity: 1.06 ± 0.08 at 1 h, 1.04 ± 0.12 at 4 h, and 1.07 ± 0.09 at 24 h. Both isomer conjugates cleared rapidly from normal tissues and exhibited very low uptake in thyroid, lacrimal and salivary glands. Paired-label biodistribution of [131I]SGMIB-NB7H6 and [211At]SAGMB-NB7H6 demonstrated similar tumor uptake and kidney clearance for the two radioconjugates. However, levels of 211At in thyroid, stomach, salivary and lacrimal glands were significantly higher (P < 0.05) that those for 131I suggesting greater dehalogenation for [211At]SAGMB-NB7H6. Finally, co-administration of [125I]SGMIB-NB7H6 and [131I]YF2 demonstrated good tumor uptake for both with considerably more rapid renal clearance for the NB7 radioconjugate. CONCLUSION NB7 radioconjugates exhibited good accumulation in PSMA-positive xenografts with rapid clearance from kidney and other normal tissues. We conclude that NB7 is a potentially useful scaffold for developing PSMA-targeted theranostics with different characteristics than current small molecule and antibody-based approaches.
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Affiliation(s)
| | | | | | | | | | | | - Niv Papo
- Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Feng Y, Sarrett SM, Meshaw RL, Vaidyanathan G, Cornejo MA, Zeglis BM, Zalutsky MR. Site-Specific Radiohalogenation of a HER2-Targeted Single-Domain Antibody Fragment Using a Novel Residualizing Prosthetic Agent. J Med Chem 2022; 65:15358-15373. [PMID: 36368007 DOI: 10.1021/acs.jmedchem.2c01331] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Because of their rapid tumor accumulation and normal tissue clearance, single-domain antibody fragments (sdAbs) are an attractive vehicle for developing radiotherapeutics labeled with the α-emitter 211At. Herein, we have evaluated iso-[211At]AGMB-PODS, a prosthetic agent that combines a functionality for residualizing radiohalogens with a phenyloxadiazolyl methylsulfone (PODS) moiety for site-specific sdAb conjugation. Iso-[211At]AGMB-PODS and its radioiodinated analogue were evaluated for thiol-selective conjugation to anti-HER2 5F7 sdAb bearing a C-terminus GGC tail. Both radiohalogenated PODS-5F7GGC conjugates were synthesized in good radiochemical yields and retained high binding affinity on HER2-positive BT474 breast carcinoma cells. Iso-[211At]AGMB-PODS-5F7GGC was considerably more stable in vitro than its maleimide analogue in the presence of cysteine and human serum albumin (HSA) and exhibited excellent tumor uptake and high in vivo stability. Superior tumor-to-kidney activity ratios were seen for both radiohalogenated PODS-5F7GGC conjugates compared with [177Lu]Lu-DOTA-PODS-5F7GGC. These results suggest that iso-[211At]AGMB-PODS-5F7GGC warrants further evaluation for the treatment of HER2-expressing malignancies.
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Affiliation(s)
- Yutian Feng
- Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Samantha M. Sarrett
- Hunter College, City University of New York, New York, New York 10021, United States
- Ph.D. Programs in Biochemistry and Chemistry, The Graduate Center, City University of New York, New York, New York 10021, United States
| | - Rebecca L. Meshaw
- Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Ganesan Vaidyanathan
- Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Mike A. Cornejo
- Hunter College, City University of New York, New York, New York 10021, United States
- Ph.D. Programs in Biochemistry and Chemistry, The Graduate Center, City University of New York, New York, New York 10021, United States
| | - Brian M. Zeglis
- Hunter College, City University of New York, New York, New York 10021, United States
- Ph.D. Programs in Biochemistry and Chemistry, The Graduate Center, City University of New York, New York, New York 10021, United States
| | - Michael R. Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, United States
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Zhou Z, McDougald D, Meshaw R, Balyasnikova I, Zalutsky MR, Vaidyanathan G. Labeling single domain antibody fragments with 18F using a novel residualizing prosthetic agent - N-succinimidyl 3-(1-(2-(2-(2-(2-[ 18F]fluoroethoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-5-(guanidinomethyl)benzoate. Nucl Med Biol 2021; 100-101:24-35. [PMID: 34146837 PMCID: PMC8448961 DOI: 10.1016/j.nucmedbio.2021.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/09/2021] [Accepted: 06/09/2021] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Labeling single domain antibody fragments (sdAbs) with 18F is an attractive strategy for immunoPET. Earlier, we developed a residualizing label, N-succinimidyl 3-((4-(4-fluorobutyl)-1H-1,2,3-triazol-1-yl)methyl)-5-(guanidinomethyl)benzoate ([18F]RL-I), synthesized via a click reaction for labeling sdAbs with 18F, that has attractive features but suffered from modest radiochemical yields and suboptimal hydrophobicity. Herein, we have evaluated the potential utility of an analogous agent, N-succinimidyl 3-(1-(2-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-5-(guanidinomethyl)benzoate ([18F]SFETGMB; [18F]RL-III) designed to address these limitations. METHODS [18F]RL-III was synthesized by the click reaction between 3-((2,3-bis(tert-butoxycarbonyl)guanidino)methyl)-5-ethynylbenzoate and 1-azido-2-(2-(2-(2-[18F]fluoroethoxy)ethoxy)ethoxy)ethane and subsequent deprotection. The anti-HER2 sdAbs 5F7 and 2Rs15d were labeled by conjugation with [18F]RL-III and compared in a paired-label fashion to the sdAbs labeled using N-succinimidyl 4-guanidinomethyl-3-[125I]iodobenzoate ([125I]SGMIB) or N-succinimidyl 3-guanidinomethyl-5-[125I]iodobenzoate (iso-[125I]SGMIB). The 18F-labeled sdAbs were evaluated in vitro using HER2-expressing breast and ovarian carcinoma cells (BT474/BT474M1 and SKOV-3) and in vivo in athymic mice bearing subcutaneous SKOV-3 or BT474 xenografts. PET imaging of athymic mice bearing either subcutaneous BT474 or intracranial BT474M1Br-Fluc xenografts after administration of [18F]RL-III-5F7 also was performed. RESULTS Radiochemical yields for the synthesis of Boc2-[18F]RL-III (21.5 ± 3.4%) were significantly higher than reported for Boc2-[18F]RL-I. The overall radiochemical yields for the synthesis of [18F]RL-III-2Rs15d and [18F]RL-III-5F7 from aqueous [18F]fluoride were 1.7 ± 0.7% and 3.8 ± 2.3%, respectively. Both sdAbs, labeled using [18F]RL-III, retained affinity and immunoreactivity to HER2. Uptake and internalization of [18F]RL-III-5F7 in HER2-expressing cells was higher than that seen for [18F]RL-III-2Rs15d. Although different xenograft models were used, [18F]RL-III-2Rs15d showed relatively high uptake in a number of normal tissues, while uptake of [18F]RL-III-5F7 was mainly in tumor and kidneys with minimal background activity. Concordant with the necropsy experiments, microPET imaging with [18F]RL-III-5F7 in the BT474 subcutaneous model demonstrated clear delineation of the tumor (12.2 ± 5.1% ID/g) with minimal background activity except in kidneys. A tumor uptake (max) of 0.98%ID/g and a tumor-to-normal brain ratio of 9.8:1 were observed for [18F]RL-III-5F7 in the intracranial model. CONCLUSIONS Although higher radiochemical yields than that reported for [18F]RL-I were obtained, considerable improvements are needed for this method to be of practical utility. Despite clear tumor delineation with [18F]RL-III-5F7 as early as 1 h, high activity levels in the kidneys remain a concern.
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Affiliation(s)
- Zhengyuan Zhou
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Darryl McDougald
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Rebecca Meshaw
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Irina Balyasnikova
- The Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
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Küppers J, Kürpig S, Bundschuh RA, Essler M, Lütje S. Radiolabeling Strategies of Nanobodies for Imaging Applications. Diagnostics (Basel) 2021; 11:1530. [PMID: 34573872 PMCID: PMC8471529 DOI: 10.3390/diagnostics11091530] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/30/2021] [Accepted: 08/20/2021] [Indexed: 02/06/2023] Open
Abstract
Nanobodies are small recombinant antigen-binding fragments derived from camelid heavy-chain only antibodies. Due to their compact structure, pharmacokinetics of nanobodies are favorable compared to full-size antibodies, allowing rapid accumulation to their targets after intravenous administration, while unbound molecules are quickly cleared from the circulation. In consequence, high signal-to-background ratios can be achieved, rendering radiolabeled nanobodies high-potential candidates for imaging applications in oncology, immunology and specific diseases, for instance in the cardiovascular system. In this review, a comprehensive overview of central aspects of nanobody functionalization and radiolabeling strategies is provided.
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Affiliation(s)
- Jim Küppers
- Department of Nuclear Medicine, University Hospital Bonn, 53127 Bonn, Germany; (S.K.); (R.A.B.); (M.E.); (S.L.)
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Feng Y, Zhou Z, McDougald D, Meshaw RL, Vaidyanathan G, Zalutsky MR. Site-specific radioiodination of an anti-HER2 single domain antibody fragment with a residualizing prosthetic agent. Nucl Med Biol 2021; 92:171-183. [PMID: 32448731 PMCID: PMC7657985 DOI: 10.1016/j.nucmedbio.2020.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION As a consequence of their small size, high stability and high affinity, single domain antibody fragments (sdAbs) are appealing targeting vectors for radiopharmaceutical development. With sdAbs binding to internalizing receptors like HER2, residualizing prosthetic agents can enhance tumor retention of radioiodine, which until now has been done with random labeling approaches. Herein we evaluate a site-specific strategy utilizing a radioiodinated, residualizing maleimido moiety and the anti-HER2 sdAb 5F7 bearing a GGC tail for conjugation. METHODS Maleimidoethyl 3-(guanidinomethyl)-5-iodobenzoate ([131I]MEGMB) and its N-succinimidyl ester analogue, iso-[125I]SGMIB, were labeled by halodestannylation and conjugated with 5F7GGC and 5F7, respectively. Radiochemical purity, immunoreactivity and binding affinity were determined. Paired-label experiments directly compared iso-[125I]SGMIB-5F7 and [131I]MEGMIB-5F7GGC with regard to internalization/residualization and affinity on HER2-expressing SKOV-3 ovarian carcinoma cells as well as biodistribution and metabolite distribution in athymic mice with subcutaneous SKOV-3 xenografts. RESULTS [131I]MEGMIB-5F7GGC had an immunoreactivity of 81.3% and Kd = 0.94 ± 0.27 nM. Internalization assays demonstrated high intracellular trapping for both conjugates, For example, at 1 h, intracellular retention was 50.30 ± 3.36% for [131I]MEGMIB-5F7GGC and 55.95 ± 3.27% for iso-[125I]SGMIB-5F7, while higher retention was seen for iso-[125I]SGMIB-5F7 at later time points. Peak tumor uptake was similar for both conjugates (8.35 ± 2.66%ID/g and 8.43 ± 2.84%ID/g for iso-[125I]SGMIB-5F7 and [131I]MEGMIB-5F7GGC at 1 h, respectively); however, more rapid normal tissue clearance was seen for [131I]MEGMIB-5F7GGC, with a 2-fold higher tumor-to-kidney ratio and a 3-fold higher tumor-to-liver ratio compared with co-injected iso-[125I]SGMIB-5F7. Consisted with this, generation of labeled catabolites in the kidneys was higher for [131I]MEGMIB-5F7GGC. CONCLUSION [131I]MEGMIB-5F7GGC offers similar tumor targeting as iso-[125I]SGMIB-5F7 but with generally lower normal tissue uptake. ADVANCES IN KNOWLEDGE AND IMPLICATION FOR PATIENT CARE The site specific nature of the [131I]MEGMIB reagent may facilitate clinical translation, particularly for sdAb with compromised affinity after random labeling.
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Affiliation(s)
- Yutian Feng
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Zhengyuan Zhou
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Darryl McDougald
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Rebecca L Meshaw
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | | | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
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Staben LR, Chen J, Cruz-Chuh JD, Del Rosario G, Go MA, Guo J, Khojasteh SC, Kozak KR, Li G, Ng C, Lewis Phillips GD, Pillow TH, Rowntree RK, Wai J, Wei B, Xu K, Xu Z, Yu SF, Zhang D, Dragovich PS. Systematic Variation of Pyrrolobenzodiazepine (PBD)-Dimer Payload Physicochemical Properties Impacts Efficacy and Tolerability of the Corresponding Antibody-Drug Conjugates. J Med Chem 2020; 63:9603-9622. [PMID: 32787101 DOI: 10.1021/acs.jmedchem.0c00691] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytotoxic pyrrolobenzodiazepine (PBD)-dimer molecules are frequently utilized as payloads for antibody-drug conjugates (ADCs), and many examples are currently in clinical development. In order to further explore this ADC payload class, the physicochemical properties of various PBD-dimer molecules were modified by the systematic introduction of acidic and basic moieties into their chemical structures. The impact of these changes on DNA binding, cell membrane permeability, and in vitro antiproliferation potency was, respectively, determined using a DNA alkylation assay, PAMPA assessments, and cell-based cytotoxicity measurements conducted with a variety of cancer lines. The modified PBD-dimer compounds were subsequently incorporated into CD22-targeting ADCs, and these entities were profiled in a variety of in vitro and in vivo experiments. The introduction of a strongly basic moiety into the PBD-dimer scaffold afforded a conjugate with dramatically worsened mouse tolerability properties relative to ADCs derived from related payloads, which lacked the basic group.
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Affiliation(s)
- Leanna R Staben
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Jinhua Chen
- WuXi AppTec Co., Ltd, 288 Fute Zhong Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | | | - Geoff Del Rosario
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Mary Ann Go
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Jun Guo
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - S Cyrus Khojasteh
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Katherine R Kozak
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Guangmin Li
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Carl Ng
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | | | - Thomas H Pillow
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Rebecca K Rowntree
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - John Wai
- WuXi AppTec Co., Ltd, 288 Fute Zhong Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - BinQing Wei
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Keyang Xu
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Zijin Xu
- WuXi AppTec Co., Ltd, 288 Fute Zhong Road, Waigaoqiao Free Trade Zone, Shanghai 200131, China
| | - Shang-Fan Yu
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Donglu Zhang
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Peter S Dragovich
- Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
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Zhou Z, Zalutsky MR, Vaidyanathan G. Labeling a TCO-functionalized single domain antibody fragment with 18F via inverse electron demand Diels Alder cycloaddition using a fluoronicotinyl moiety-bearing tetrazine derivative. Bioorg Med Chem 2020; 28:115634. [PMID: 32773089 DOI: 10.1016/j.bmc.2020.115634] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/27/2020] [Accepted: 06/28/2020] [Indexed: 02/07/2023]
Abstract
Single domain antibody fragments (sdAbs) exhibit a rapid tumor uptake and fast blood clearance amenable for labeling with 18F (t½ = 110 min) but suffer from high kidney accumulation. Previously, we developed a method for 18F-labeling of sdAbs via trans-cyclooctene (TCO)-tetrazine (Tz) inverse electron demand Diel's Alder cycloaddition reaction (IEDDAR) that incorporated a renal brush border enzyme (RBBE)-cleavable linker. Although >15 fold reduction in kidney activity levels was achieved, tumor uptake was compromised. Here we investigate whether replacing the [18F]AlF-NOTA moiety with [18F]fluoronicotinyl would rectify this problem. Anti-HER2 sdAb 5F7 was first derivatized with a TCO-containing agent that included the RBBE-cleavable linker GlyLys (GK) and a PEG chain, and then subjected to IEDDAR with 6-[18F]fluoronicotinyl-PEG4-methyltetrazine to provide [18F]FN-PEG4-Tz-TCO-GK-PEG4-5F7 ([18F]FN-GK-5F7). For comparisons, a control lacking GK linker and 5F7 labeled using residualizing N-succinimidyl 3-guanidinomethyl-5-[125I]iodobenzoate (iso-[125I]SGMIB) also were synthesized. Radiochemical purity, affinity (KD) and immunoreactive fraction of [18F]FN-GK-5F7 were 99%, 5.4 ± 0.7 nM and 72.5 ± 4.3%, respectively. Tumor uptake of [18F]FN-GK-5F7 in athymic mice bearing subcutaneous SKOV3 xenografts (3.7 ± 1.2% ID/g and 3.4 ± 1.0% ID/g at 1 h and 3 h, respectively) was 2- to 3-fold lower than for co-injected iso-[125I]SGMIB-5F7 (6.9 ± 1.9 %ID/g and 8.7 ± 3.0 %ID/g). However, due to its 6-fold lower kidney activity levels, tumor-to-kidney ratios for [18F]FN-GK-5F7 were 3-4 times higher than those for co-injected iso-[125I]SGMIB-5F7 as well as those observed for the 18F conjugate lacking the RBBE-cleavable linker. Micro-PET/CT imaging of [18F]FN-GK-5F7 in mice with SKOV-3 subcutaneous xenografts clearly delineated tumor as early as 1 h with minimal activity in the kidneys; however, there was considerable activity in gallbladder and intestines. Although the tumor uptake of [18F]FN-GK-5F7 was unexpectedly disappointing, incorporating an alternative RBBE-cleavable linker into this labeling strategy may ameliorate this problem.
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Affiliation(s)
- Zhengyuan Zhou
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
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Fujiki K, Kanayama Y, Yano S, Sato N, Yokokita T, Ahmadi P, Watanabe Y, Haba H, Tanaka K. 211At-labeled immunoconjugate via a one-pot three-component double click strategy: practical access to α-emission cancer radiotherapeutics. Chem Sci 2018; 10:1936-1944. [PMID: 30881623 PMCID: PMC6385556 DOI: 10.1039/c8sc04747b] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/19/2018] [Indexed: 01/04/2023] Open
Abstract
α-Emission radiotherapeutics has potential to be one of most effective cancer therapeutics. Herein, we report a facile synthesis of an 211At-labeled immunoconjugate for use as an α-emission molecular targeting therapy. We synthesized a tetrazine probe modified with closo-decaborate(2-), a prosthetic group that forms a bioavailable stable complex with 211At. Our one-pot three-component double-click labeling method was used to attach decaborate to trastuzumab (anti-HER2 antibody) using decaborate-tetrazine and TCO-aldehyde probes without reducing the antibody binding affinity. Labeling the decaborate-attached trastuzumab with 211At produced in the cyclotron at the RIKEN Nishina Center, at which highly radioactive 211At can be produced, readily furnished the 211At-labeled trastuzumab with a maximum specific activity of 15 MBq μg-1 and retention of the native binding affinity. Intratumor injection of the 211At-labeled trastuzumab in BALB/c nude mice implanted with HER2-expressing epidermoid cancer cells yielded efficient accumulation at the targeted tumor site as well as effective suppression of tumor growth.
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Affiliation(s)
- Katsumasa Fujiki
- Biofunctional Synthetic Chemistry Laboratory , RIKEN Cluster for Pioneering Research , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan . .,GlycoTargeting Research Laboratory , RIKEN Baton Zone Program , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan
| | - Yousuke Kanayama
- Laboratory for Pathophysiological and Health Science , RIKEN Center for Biosystems Dynamics Research , 6-7-3 Minatojima-minamimachi, Chuo-ku , Kobe , Hyogo 650-0047 , Japan
| | - Shinya Yano
- Nuclear Chemistry Research Team , RIKEN Nishina Center for Accelerator-Based Science , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan
| | - Nozomi Sato
- Nuclear Chemistry Research Team , RIKEN Nishina Center for Accelerator-Based Science , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan
| | - Takuya Yokokita
- Nuclear Chemistry Research Team , RIKEN Nishina Center for Accelerator-Based Science , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan
| | - Peni Ahmadi
- Biofunctional Synthetic Chemistry Laboratory , RIKEN Cluster for Pioneering Research , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan .
| | - Yasuyoshi Watanabe
- Laboratory for Pathophysiological and Health Science , RIKEN Center for Biosystems Dynamics Research , 6-7-3 Minatojima-minamimachi, Chuo-ku , Kobe , Hyogo 650-0047 , Japan
| | - Hiromitsu Haba
- Nuclear Chemistry Research Team , RIKEN Nishina Center for Accelerator-Based Science , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan
| | - Katsunori Tanaka
- Biofunctional Synthetic Chemistry Laboratory , RIKEN Cluster for Pioneering Research , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan . .,GlycoTargeting Research Laboratory , RIKEN Baton Zone Program , 2-1 Hirosawa , Wako , Saitama 351-0198 , Japan.,Biofunctional Chemistry Laboratory , A. Butlerov Institute of Chemistry , Kazan Federal University , 18 Kremlyovskaya Street , Kazan 420008 , Russia
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Zhou Z, McDougald D, Devoogdt N, Zalutsky MR, Vaidyanathan G. Labeling Single Domain Antibody Fragments with Fluorine-18 Using 2,3,5,6-Tetrafluorophenyl 6-[ 18F]Fluoronicotinate Resulting in High Tumor-to-Kidney Ratios. Mol Pharm 2018; 16:214-226. [PMID: 30427188 DOI: 10.1021/acs.molpharmaceut.8b00951] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
ImmunoPET agents are being investigated to assess the status of epidermal growth factor receptor 2 (HER2) in breast cancer patients with the goal of selecting those likely to benefit from HER2-targeted therapies and monitoring their progress after these treatments. We have been exploring the use of single domain antibody fragments (sdAbs) labeled with 18F using residualizing prosthetic agents for this purpose. In this study, we have labeled two sdAbs that bind to different domains on the HER2 receptor, 2Rs15d and 5F7, using 2,3,5,6-tetrafluorophenyl 6-[18F]fluoronicotinate ([18F]TFPFN) and evaluated their HER2 targeting properties in vitro and in vivo. The overall decay-corrected radiochemical yield for the synthesis of [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 was 5.7 ± 3.6 and 4.0 ± 2.0%, respectively. The radiochemical purity of labeled sdAbs was >95%, immunoreactive fractions were about 60%, and affinity was in the low nanomolar range. Intracellularly trapped activity from [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 in HER2-expressing SKOV-3 ovarian and BT474M1 breast carcinoma cells were similar to the sdAbs labeled using the previously validated radioiodination residualizing prosthetic agents N-succinimidyl 4-guanidinomethyl-3-[125I]iodobenzoate ([125I]SGMIB) and N-succinimidyl 3-guanidinomethyl-5-[125I]iodobenzoate ( iso-[125I]SGMIB). Intracellular activity was about 2-fold higher for radiolabeled 5F7 compared with 2Rs15d for both 18F and 125I. While tumor uptake of both [18F]TFPFN-2Rs15d and [18F]TFPFN-5F7 was comparable to those for the coadministered 125I-labeled sdAb, renal uptake of the 18F-labeled sdAbs was substantially lower. In microPET images, the tumor was clearly delineated in SKOV-3 and BT474 xenograft-bearing athymic mice with low levels of background activity in normal tissues, except the bladder. These results indicate that the [18F]TFPFN prosthetic group could be a valuable reagent for developing sdAb-based immunoPET imaging agents.
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Affiliation(s)
- Zhengyuan Zhou
- Department of Radiology , Duke University Medical Center , Durham , North Carolina 27710 , United States
| | - Darryl McDougald
- Department of Radiology , Duke University Medical Center , Durham , North Carolina 27710 , United States
| | - Nick Devoogdt
- In vivo Cellular and Molecular Imaging laboratory , Vrije Universiteit Brussel, (VUB) , 1090 , Brussels , Belgium
| | - Michael R Zalutsky
- Department of Radiology , Duke University Medical Center , Durham , North Carolina 27710 , United States
| | - Ganesan Vaidyanathan
- Department of Radiology , Duke University Medical Center , Durham , North Carolina 27710 , United States
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Fluorine-18 Labeling of the HER2-Targeting Single-Domain Antibody 2Rs15d Using a Residualizing Label and Preclinical Evaluation. Mol Imaging Biol 2018; 19:867-877. [PMID: 28409338 DOI: 10.1007/s11307-017-1082-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE Our previous studies with F-18-labeled anti-HER2 single-domain antibodies (sdAbs) utilized 5F7, which binds to the same epitope on HER2 as trastuzumab, complicating its use for positron emission tomography (PET) imaging of patients undergoing trastuzumab therapy. On the other hand, sdAb 2Rs15d binds to a different epitope on HER2 and thus might be a preferable vector for imaging in these patients. The aim of this study was to evaluate the tumor targeting of F-18 -labeled 2Rs15d in HER2-expressing breast carcinoma cells and xenografts. PROCEDURES sdAb 2Rs15d was labeled with the residualizing labels N-succinimidyl 3-((4-(4-[18F]fluorobutyl)-1H-1,2,3-triazol-1-yl)methyl)-5-(guanidinomethyl)benzoate ([18F]RL-I) and N-succinimidyl 4-guanidinomethyl-3-[125I]iodobenzoate ([125I]SGMIB), and the purity and HER2-specific binding affinity and immunoreactivity were assessed after labeling. The biodistribution of I-125- and F-18-labeled 2Rs15d was determined in SCID mice bearing subcutaneous BT474M1 xenografts. MicroPET/x-ray computed tomograph (CT) imaging of [18F]RL-I-2Rs15d was performed in this model and compared to that of nonspecific sdAb [18F]RL-I-R3B23. MicroPET/CT imaging was also done in an intracranial HER2-positive breast cancer brain metastasis model after administration of 2Rs15d-, 5F7-, and R3B23-[18F]RL-I conjugates. RESULTS [18F]RL-I was conjugated to 2Rs15d in 40.8 ± 9.1 % yield and with a radiochemical purity of 97-100 %. Its immunoreactive fraction (IRF) and affinity for HER2-specific binding were 79.2 ± 5.4 % and 7.1 ± 0.4 nM, respectively. [125I]SGMIB was conjugated to 2Rs15d in 58.4 ± 8.2 % yield and with a radiochemical purity of 95-99 %; its IRF and affinity for HER2-specific binding were 79.0 ± 12.9 % and 4.5 ± 0.8 nM, respectively. Internalized radioactivity in BT474M1 cells in vitro for [18F]RL-I-2Rs15d was 43.7 ± 3.6, 36.5 ± 2.6, and 21.7 ± 1.2 % of initially bound radioactivity at 1, 2, and 4 h, respectively, and was similar to that seen for [125I]SGMIB-2Rs15d. Uptake of [18F]RL-I-2Rs15d in subcutaneous xenografts was 16-20 %ID/g over 1-3 h. Subcutaneous tumor could be clearly delineated by microPET/CT imaging with [18F]RL-I-2Rs15d but not with [18F]RL-I-R3B23. Intracranial breast cancer brain metastases could be visualized after intravenous administration of both [18F]RL-I-2Rs15d and [18F]RL-I-5F7. CONCLUSIONS Although radiolabeled 2Rs15d conjugates exhibited lower tumor cell retention both in vitro and in vivo than that observed previously for 5F7, given that it binds to a different epitope on HER2 from those targeted by the clinically utilized HER2-targeted therapeutic antibodies trastuzumab and pertuzumab, F-18-labeled 2Rs15d has potential for assessing HER2 status by PET imaging after trastuzumab and/or pertuzumab therapy.
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Vivier D, Sharma SK, Zeglis BM. Understanding the in vivo fate of radioimmunoconjugates for nuclear imaging. J Labelled Comp Radiopharm 2018; 61:672-692. [PMID: 29665104 PMCID: PMC6432633 DOI: 10.1002/jlcr.3628] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/16/2018] [Accepted: 04/03/2018] [Indexed: 12/17/2022]
Abstract
Over the past 25 years, antibodies have emerged as extraordinarily promising vectors for the delivery of radionuclides to tumors for nuclear imaging. While radioimmunoconjugates often produce very high activity concentrations in target tissues, they also are frequently characterized by elevated activity concentrations in healthy organs as well. The root of this background uptake lies in the complex network of biological interactions between the radioimmunoconjugate and the subject. In this review, we seek to provide an overview of these interactions and thus paint a general picture of the in vivo fate of radioimmunoconjugates. To cover the entire story, we have divided our discussion into 2 parts. First, we will address the path of the entire radioimmunoconjugate as it travels through the body. And second, we will cover the fate of the radionuclide itself, as its course can diverge from the antibody under certain circumstances. Ultimately, our goal is to provide the nuclear imaging field with a resource covering these important-yet often underestimated-pathways.
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Affiliation(s)
- Delphine Vivier
- Department of Chemistry, Hunter College and the Graduate Center of the City University of New York, New York, NY, USA
| | - Sai Kiran Sharma
- Department of Radiology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Brian M. Zeglis
- Department of Chemistry, Hunter College and the Graduate Center of the City University of New York, New York, NY, USA
- Department of Radiology and the Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Radiology, Weill Cornell Medical College, New York, NY, USA
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12
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Pruszynski M, Kang CM, Koumarianou E, Vaidyanathan G, Zalutsky MR. d-Amino Acid Peptide Residualizing Agents for Protein Radioiodination: Effect of Aspartate for Glutamate Substitution. Molecules 2018; 23:molecules23051223. [PMID: 29783774 PMCID: PMC6099567 DOI: 10.3390/molecules23051223] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/15/2018] [Accepted: 05/17/2018] [Indexed: 11/29/2022] Open
Abstract
The residualizing prosthetic agent Nε-(3-[*I]iodobenzoyl)-Lys5-Nα-maleimido-Gly1-d-GEEEK ([*I]IB-Mal-d-GEEEK) showed promise for the radioiodination of monoclonal antibodies (mAbs) that bind to internalizing molecular targets. Although enhanced tumor uptake was achieved in these studies, elevated kidney accumulation also was observed, particularly with low-molecular-weight, single-domain antibody fragments (sdAbs). Here, we developed an analogous agent (IB-Mal-d-GDDDK), in which glutamate residues (E) were replaced with aspartates (D) to determine whether this modification could decrease renal uptake. [125I]IB-Mal-d-GDDDK and [131I]IB-Mal-d-GEEEK were synthesized with similar radiochemical yields (60–80%) and coupled to the anti-HER2 sdAb 5F7 at 50–60% efficiency. Paired-label internalization assays in vitro indicated similar levels of intracellular activity residualization in HER2-expressing BT474M1 cells for [125I]IB-Mal-d-GDDDK-5F7 and [131I]IB-Mal-d-GEEEK-5F7. A paired-label biodistribution comparison of the two labeled conjugates was performed in mice with HER2-expressing SKOV-3 xenografts, and the results of this study indicated that renal uptake at 1 h was 127.5 ± 18.7% ID/g and 271.4 ± 66.6% ID/g for [125I]IB-Mal-d-GDDDK-5F7 and [131I]IB-Mal-d-GEEEK-5F7, respectively. The tumor uptake of the two radioconjugates was not significantly different. These results demonstrate that substitution of E with D in the IB-Mal-d-GEEEK construct reduced kidney accumulation of the sdAb. However, renal activity levels need to be reduced further if d-amino acid derived prosthetic agents are to be of practical value for labeling low molecular weight biomolecules such as sdAbs.
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Affiliation(s)
- Marek Pruszynski
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
- Present address: Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Poland.
| | - Choong Mo Kang
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
- Present address: Korea Institute of Radiological and Medical Sciences, Seoul 01812, Korea.
| | - Eftychia Koumarianou
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
- Present address: Laboratory for Translational and Molecular Imaging, Duke-National University of Singapore Medical School, Singapore 169857, Singapore.
| | | | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
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Choi J, Vaidyanathan G, Koumarianou E, Kang CM, Zalutsky MR. Astatine-211 labeled anti-HER2 5F7 single domain antibody fragment conjugates: radiolabeling and preliminary evaluation. Nucl Med Biol 2018; 56:10-20. [PMID: 29031230 PMCID: PMC5732883 DOI: 10.1016/j.nucmedbio.2017.09.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/28/2017] [Accepted: 09/14/2017] [Indexed: 01/11/2023]
Abstract
INTRODUCTION Derived from heavy chain only camelid antibodies, ~15-kDa single-domain antibody fragments (sdAbs) are an attractive platform for developing molecularly specific imaging probes and targeted radiotherapeutics. The rapid tumor accumulation and normal tissue clearance of sdAbs might be ideal for use with 211At, a 7.2-h half-life α-emitter, if appropriate labeling chemistry can be devised to trap 211At in cancer cells after sdAb binding. This study evaluated two reagents, [211At]SAGMB and iso-[211At]SAGMB, for this purpose. METHODS [211At]SAGMB and iso-[211At]SAGMB, and their radioiodinated analogues [131I]SGMIB and iso-[131I]SGMIB, were synthesized by halodestannylation and reacted with the anti-HER2 sdAb 5F7. Radiochemical purity, immunoreactivity and binding affinity were determined. Paired-label internalization assays on HER2-expressing BT474M1 breast carcinoma cells directly compared [131I]SGMIB-5F7/[211At]SAGMB-5F7 and iso-[131I]SGMIB-5F7/iso-[211At]SAGMB-5F7 tandems. The biodistribution of the two tandems was evaluated in SCID mice with subcutaneous BT474M1 xenografts. RESULTS Radiochemical yields for Boc2-iso-[211At]SAGMB and Boc2-[211At]SAGMB synthesis, and efficiencies for coupling of iso-[211At]SAGMB and [211At]SAGMB to 5F7 were similar, with radiochemical purities of [211At]SAGMB-5F7 and iso-[211At]SAGMB-5F7 >98%. iso-[211At]SAGMB-5F7 and [211At]SAGMB-5F7 had immunoreactive fractions >80% and HER2 binding affinities of less than 5 nM. Internalization assays demonstrated high intracellular trapping of radioactivity, with little difference observed between corresponding 211At- and 131I-labeled 5F7 conjugates. Higher BT474M1 intracellular retention was observed from 1-6 h for the iso-conjugates (iso-[211At]SAGMB-5F7, 74.3 ± 2.8%, vs. [211At]SAGMB-5F7, 63.7 ± 0.4% at 2 h) with the opposite behavior observed at 24 h. Peak tumor uptake for iso-[211At]SAGMB-5F7 was 23.4 ± 2.2% ID/g at 4 h, slightly lower than its radioiodinated counterpart, but significantly higher than observed with [211At]SAGMB-5F7. Except in kidneys and lungs, tumor-to-normal organ ratios for iso-[211At]SAGMB-5F7 were greater than 10:1 by 2 h, and significantly higher than those for [211At]SAGMB-5F7. CONCLUSION These 211At-labeled sdAb conjugates, particularly iso-[211At]SAGMB-5F7, warrant further evaluation for targeted α-particle radiotherapy of HER2-expressing cancers.
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Affiliation(s)
- Jaeyeon Choi
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Ganesan Vaidyanathan
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Eftychia Koumarianou
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Choong Mo Kang
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, North Carolina, 27710, USA.
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Dekempeneer Y, Keyaerts M, Krasniqi A, Puttemans J, Muyldermans S, Lahoutte T, D'huyvetter M, Devoogdt N. Targeted alpha therapy using short-lived alpha-particles and the promise of nanobodies as targeting vehicle. Expert Opin Biol Ther 2016; 16:1035-47. [PMID: 27145158 PMCID: PMC4940885 DOI: 10.1080/14712598.2016.1185412] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Introduction: The combination of a targeted biomolecule that specifically defines the target and a radionuclide that delivers a cytotoxic payload offers a specific way to destroy cancer cells. Targeted radionuclide therapy (TRNT) aims to deliver cytotoxic radiation to cancer cells and causes minimal toxicity to surrounding healthy tissues. Recent advances using α-particle radiation emphasizes their potential to generate radiation in a highly localized and toxic manner because of their high level of ionization and short range in tissue. Areas covered: We review the importance of targeted alpha therapy (TAT) and focus on nanobodies as potential beneficial vehicles. In recent years, nanobodies have been evaluated intensively as unique antigen-specific vehicles for molecular imaging and TRNT. Expert opinion: We expect that the efficient targeting capacity and fast clearance of nanobodies offer a high potential for TAT. More particularly, we argue that the nanobodies’ pharmacokinetic properties match perfectly with the interesting decay properties of the short-lived α-particle emitting radionuclides Astatine-211 and Bismuth-213 and offer an interesting treatment option particularly for micrometastatic cancer and residual disease.
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Affiliation(s)
- Yana Dekempeneer
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Marleen Keyaerts
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium.,b Nuclear Medicine Department , UZ Brussel , Brussels , Belgium
| | - Ahmet Krasniqi
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Janik Puttemans
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Serge Muyldermans
- c Vrije Universiteit Brussel , Laboratory of Cellular and Molecular Immunology , Brussels , Belgium
| | - Tony Lahoutte
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium.,b Nuclear Medicine Department , UZ Brussel , Brussels , Belgium
| | - Matthias D'huyvetter
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
| | - Nick Devoogdt
- a Vrije Universiteit Brussel, In Vivo Cellular and Molecular Imaging , Brussels , Belgium
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Vaidyanathan G, McDougald D, Choi J, Pruszynski M, Koumarianou E, Zhou Z, Zalutsky MR. N-Succinimidyl 3-((4-(4-[(18)F]fluorobutyl)-1H-1,2,3-triazol-1-yl)methyl)-5-(guanidinomethyl)benzoate ([(18)F]SFBTMGMB): a residualizing label for (18)F-labeling of internalizing biomolecules. Org Biomol Chem 2016; 14:1261-71. [PMID: 26645790 PMCID: PMC4720566 DOI: 10.1039/c5ob02258d] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Residualizing labeling methods for internalizing peptides and proteins are designed to trap the radionuclide inside the cell after intracellular degradation of the biomolecule. The goal of this work was to develop a residualizing label for the (18)F-labeling of internalizing biomolecules based on a template used successfully for radioiodination. N-Succinimidyl 3-((4-(4-[(18)F]fluorobutyl)-1H-1,2,3-triazol-1-yl)methyl)-5-(bis-Boc-guanidinomethyl)benzoate ([(18)F]SFBTMGMB-Boc2) was synthesized by a click reaction of an azide precursor and [(18)F]fluorohexyne in 8.5 ± 2.8% average decay-corrected radiochemical yield (n = 15). An anti-HER2 nanobody 5F7 was labeled with (18)F using [(18)F]SFBTMGMB ([(18)F]RL-I), obtained by the deprotection of [(18)F]SFBTMGMB-Boc2, in 31.2 ± 6.7% (n = 5) conjugation efficiency. The labeled nanobody had a radiochemical purity of >95%, bound to HER2-expressing BT474M1 breast cancer cells with an affinity of 4.7 ± 0.9 nM, and had an immunoreactive fraction of 62-80%. In summary, a novel residualizing prosthetic agent for labeling biomolecules with (18)F has been developed. An anti-HER2 nanobody was labeled using this prosthetic group with retention of affinity and immunoreactivity to HER2.
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Affiliation(s)
- Ganesan Vaidyanathan
- Department of Radiology and Duke University Medical Center, Durham, North Carolina, USA.
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Dzandzi JPK, Beckford Vera DR, Genady AR, Albu SA, Eltringham-Smith LJ, Capretta A, Sheffield WP, Valliant JF. Fluorous Analogue of Chloramine-T: Preparation, X-ray Structure Determination, and Use as an Oxidant for Radioiodination and s-Tetrazine Synthesis. J Org Chem 2015; 80:7117-25. [DOI: 10.1021/acs.joc.5b00988] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
| | | | - Afaf R. Genady
- Department
of Chemistry, Faculty of Science, Tanta University, Tanta, 31527 Egypt
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