| 1. |
- Altai, Mohamed, et al.
(author)
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Feasibility of Affibody-Based Bioorthogonal Chemistry Mediated Radionuclide Pretargeting
- 2016
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In: Journal of Nuclear Medicine. - : SOC NUCLEAR MEDICINE. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 57:3, s. 431-436
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Journal article (peer-reviewed)abstract
- Affibody molecules constitute a new class of probes for radionuclide tumor targeting. The small size of Affibody molecules is favorable for rapid localization in tumors and clearance from circulation. However, high renal reabsorption of Affibody molecules prevents the use of residualizing radiometals, including several promising low-energy (beta- and alpha-emitters, for radionuclide therapy. We tested a hypothesis that Affibody-based pretargeting mediated by a bioorthogonal interaction between trans-cyclooctene (TCO) and tetrazine would provide higher accumulation of radiometals in tumor xenografts than in the kidneys. Methods: TCO was conjugated to the anti-human epidermal growth factor receptor 2 (HER2) Affibody molecule Z(2395). DOTA-tetrazine was labeled with In-111 and Lu-177. In vitro pretargeting was studied in HER2-expressing SKOV-3 and BT474 cell lines. In vivo studies were performed on BALB/C nu/nu mice bearing SKOV-3 xenografts. Results: I-125-Z(2395)-TCO bound specifically to HER2-expressing cells in vitro with an affinity of 45 +/- 16 pM. In-111-tetrazine bound specifically and selectively to Z(2325)-TCO pretreated cells. In vivo studies demonstrated HER2-specific I-125-Z(2395)-TCO accumulation in xenografts. TCO-mediated In-111-tetrazine localization was shown in tumors, when the radiolabeled tracer was injected 4 h after an injection of Z(2395)-TCO. At 1 h after injection, the tumor uptake of In-111-tetrazine and Lu-177-tetrazine was approximately 2-fold higher than the renal uptake. Pretargeting provided more than a 56-fold reduction of renal uptake of In-111 in comparison with direct targeting. Conclusion: The feasibility of Affibody-based bioorthogonal chemistry-mediated pretargeting was demonstrated. The use of pre-targeting provides a substantial reduction of radiometal accumulation in kidneys, creating preconditions for palliative radionuclide therapy.
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| 2. |
- Altai, Mohamed, et al.
(author)
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Preclinical evaluation of anti-HER2 Affibody molecules site-specifically labeled with In-111 using a maleimido derivative of NODAGA
- 2012
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In: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 39:4, s. 518-529
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Journal article (peer-reviewed)abstract
- Introduction: Affibody molecules have demonstrated potential for radionuclide molecular imaging. The aim of this study was to synthesize and evaluate a maleimido derivative of the 1,4,7-triazacyclononane-l-glutaric acid-4,7-diacetic acid (NODAGA) for site-specific labeling of anti-HER2 Affibody molecule. Methods: The maleimidoethylmonoamide NODAGA (MMA-NODAGA) was synthesized and conjugated to Z(HER2:2395) Affibody molecule having a C-terminal cysteine. Labeling efficiency, binding specificity to and cell internalization by HER2-expressing cells of [In-111-MMA-NODAGA-Cys(61)]-Z(HER2:2395) were studied. Biodistribution of [In-111-MMA-NODAGA-Cys(61)]-Z(HER2:2395) and [In-111-MMA-DOTA-Cys(61)]-Z(HER2:2395) was compared in mice. Results: The affinity of [MMA-NODAGA-Cys(61)]-Z(HER2:2395) binding to HER2 was 67 pM. The In-1111-labeling yield was 99.6%+/- 0.5% after 30 min at 60 degrees C. [In-111-MMA-NODAGA-Cys(61)]-Z(HER2:2395) bound specifically to HER2-expressing cells in vitro and in vivo. Tumor uptake of [In-111-MMA-NODAGA-Cys(61)]-ZHER(2:2395) in mice bearing DU-145 xenografts (4.7%+/- 0.8% ID/g) was lower than uptake of [In-111-MMA-DOTA-Cys(61)]-Z(HER2:2395) (7.5%+/- 1.6% ID/g). However, tumor-to-organ ratios were higher for [In-111-MMA-NODAGA-Cys(61)]-Z(HER2:2395) due to higher clearance rate from normal tissues. Conclusions: MMA-NODAGA is a promising chelator for site-specific labeling of targeting proteins containing unpaired cysteine. Appreciable influence of chelators on targeting properties of Affibody molecules was demonstrated.
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| 3. |
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| 4. |
- Honarvar, Hadis, et al.
(author)
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Position for site-specific attachment of a DOTA chelator to synthetic affibody molecules has a different influence on the targeting properties of 68Ga-Compared to 111in-labeled conjugates
- 2014
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In: Molecular Imaging. - : SAGE Publications. - 1535-3508 .- 1536-0121. ; 13:10
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Journal article (peer-reviewed)abstract
- Affibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the Cterminus. The biodistribution of 68Ga-and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.
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| 5. |
- Malmberg, Jennie, et al.
(author)
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Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with 111In using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts.
- 2012
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In: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 39:3, s. 481-492
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Journal article (peer-reviewed)abstract
- PURPOSE: In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer. METHODS: A synthetic variant of the anti-HER2 Z(HER2:342) Affibody molecule, Z(HER2:S1), was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with (111)In, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts. RESULTS: The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1), respectively. A comparative study of (111)In-labelled DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1) in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. (111)In-NODAGA-Z(HER2:S1) had the most rapid clearance from blood and healthy tissues. (111)In-NOTA-Z(HER2:S1) showed high hepatic uptake and was excluded from further evaluation. (111)In-DOTA-Z(HER2:S1) and (111)In-NODAGA-Z(HER2:S1) demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of (111)In-NODAGA-Z(HER2:S1), 5.6 ± 0.4%ID/g, was significantly lower than the uptake of (111)In-DOTA-Z(HER2:S1), 7.4 ± 0.5%ID/g, presumably because of lower bioavailability due to more rapid clearance. (111)In-NODAGA-Z(HER2:S1) provided higher tumour-to-blood ratio, but somewhat lower tumour-to-liver, tumour-to-spleen and tumour-to-bone ratios. CONCLUSION: Since distant prostate cancer metastases are situated in bone or bone marrow, the higher tumour-to-bone ratio is the most important. This renders (111)In-DOTA-Z(HER2:S1) a preferable agent for imaging of HER2 expression in disseminated prostate cancer.
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| 6. |
- Malmberg, Jennie, et al.
(author)
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Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with In-111 using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts
- 2012
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In: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 39:3, s. 481-492
-
Journal article (peer-reviewed)abstract
- Purpose In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer. Methods A synthetic variant of the anti-HER2 Z(HER2:342) Affibody molecule, Z(HER2:S1), was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with In-111, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts. Results The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1), respectively. A comparative study of In-111-labelled DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1) in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. In-111-NODAGA-Z(HER2:S1) had the most rapid clearance from blood and healthy tissues. In-111-NOTA-Z(HER2:S1) showed high hepatic uptake and was excluded from further evaluation. In-111-DOTA-Z(HER2:S1) and In-111-NODAGAZHER2: S1 demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of In-111-NODAGA-Z(HER2:S1), 5.6 +/- 0.4% ID/g, was significantly lower than the uptake of In-111-DOTA-Z(HER2:S1), 7.4 +/- 0.5% ID/g, presumably because of lower bioavailability due to more rapid clearance. In-111-NODAGA-Z(HER2:S1) provided higher tumour-to-blood ratio, but somewhat lower tumour-to-liver, tumour-to-spleen and tumour-to-bone ratios. Conclusion Since distant prostate cancer metastases are situated in bone or bone marrow, the higher tumour-to-bone ratio is the most important. This renders In-111-DOTA-Z(HER2:S1) a preferable agent for imaging of HER2 expression in disseminated prostate cancer.
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| 7. |
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| 8. |
- Perols, Anna, et al.
(author)
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Influence of DOTA Chelator Position on Biodistribution and Targeting Properties of In-111-Labeled Synthetic Anti-HER2 Affibody Molecules
- 2012
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In: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 23:8, s. 1661-1670
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Journal article (peer-reviewed)abstract
- Affibody molecules are a class of affinity proteins. Their small size (7 kDa) in combination with the high (subnanomolar) affinity for a number of cancer-associated molecular targets makes them suitable for molecular imaging. Earlier studies demonstrated that the selection of radionuclide and chelator may substantially influence the tumor-targeting properties of affibody molecules. Moreover, the placement of chelators for labeling of affibody molecules with Tc-99m at different positions in affibody molecules influenced both blood clearance rate and uptake in healthy tissues. This introduces an opportunity to improve the contrast of affibody-mediated imaging. In this comparative study, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was conjugated to the synthetic affibody molecule Z(HER2:S1) at three different positions: DOTA-A1-Z(HER2:S1) (N-terminus), DOTA-K58-Z(HER2:S1) (C-terminus), and DOTA-K50-Z(HER2:S1) (middle of helix 3). The affinity for HER2 differed slightly among the variants and the K-D values were determined to be 133 pM, 107 pM and 94 pM for DOTA-A1-Z(HER2:S1), DOTA-K50-Z(HER2:S1), and DOTA-K58-Z(HER2:S1), respectively. Z(HER2:S1) K50-DOTA showed a slightly lower melting point (57 degrees C) compared to DOTA-A1-Z(HER2:S1) (64 degrees C) and DOTA-K5S-Z(HER2:S1) (62 degrees C), but all variants showed good refolding properties after heat treatment All conjugates were successfully labeled with In-III resulting in a radiochemical yield of 99% with preserved binding capacity. In vitro specificity studies using SKOV-3 and LS174T cell lines showed that the binding of the radiolabeled compounds was HER2 receptor mediated, which also was verified in vivo using BALB/C nu/nu mice with LS174T and Ramos lymphoma xenografts. The three conjugates all showed specific uptake in L5174T xenografts in nude mice, where DOTA-A1-Z(HER2:S1) and DOTA-K58-Z(HER2:S1) showed the highest uptake. Overall, DOTA-K58-Z(HER2:S1) provided the highest tumor-to-blood ratio, which is important for a high contrast imaging. In conclusion, the positioning of the DOTA chelator influences the cellular processing and the biodistribution pattern of radiolabeled affibody molecules, creating preconditions for imaging optimization.
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| 9. |
- Strand, Joanna, et al.
(author)
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Influence of Macrocyclic Chelators on the Targeting Properties of Ga-68-Labeled Synthetic Affibody Molecules : Comparison with In-111-Labeled Counterparts
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8, s. e70028-
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Journal article (peer-reviewed)abstract
- Affibody molecules are a class of small (7 kDa) non-immunoglobulin scaffold-based affinity proteins, which have demonstrated substantial potential as probes for radionuclide molecular imaging. The use of positron emission tomography (PET) would further increase the resolution and quantification accuracy of Affibody-based imaging. The rapid in vivo kinetics of Affibody molecules permit the use of the generator-produced radionuclide Ga-68 (T-1/2 = 67.6 min). Earlier studies have demonstrated that the chemical nature of chelators has a substantial influence on the biodistribution properties of Affibody molecules. To determine an optimal labeling approach, the macrocyclic chelators 1,4,7,10-tetraazacylododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-N,N,N-triacetic acid (NOTA) and 1-(1,3-carboxypropyl)-1,4,7- triazacyclononane-4,7-diacetic acid (NODAGA) were conjugated to the N-terminus of the synthetic Affibody molecule Z(HER2:S1) targeting HER2. Affibody molecules were labeled with Ga-68, and their binding specificity and cellular processing were evaluated. The biodistribution of Ga-68-DOTA-Z(HER2:S1), Ga-68-NOTA-Z(HER2:S1) and Ga-68-NODAGA-Z(HER2:S1), as well as that of their In-111-labeled counterparts, was evaluated in BALB/C nu/nu mice bearing HER2-expressing SKOV3 xenografts. The tumor uptake for Ga-68-DOTA-Z(HER2:S1) (17.9 +/- 0.7%IA/g) was significantly higher than for both Ga-68-NODAGA-Z(HER2:S1) (16.13 +/- 0.67%IA/g) and Ga-68-NOTA-Z(HER2:S1) (13 +/- 3%IA/g) at 2 h after injection. Ga-68-NODAGA-Z(HER2:S1) had the highest tumor-to-blood ratio (60 +/- 10) in comparison with both Ga-68-DOTA-Z(HER2:S1) (28 +/- 4) and Ga-68-NOTA-Z(HER2:S1) (42 +/- 11). The tumor-to-liver ratio was also higher for Ga-68-NODAGA-Z(HER2:S1) (7 +/- 2) than the DOTA and NOTA conjugates (5.5 +/- 0.6 vs. 3.3 +/- 0.6). The influence of chelator on the biodistribution and targeting properties was less pronounced for Ga-68 than for In-111. The results of this study demonstrate that macrocyclic chelators conjugated to the N-terminus have a substantial influence on the biodistribution of HER2-targeting Affibody molecules labeled with Ga-68. This can be utilized to enhance the imaging contrast of PET imaging using Affibody molecules and improve the sensitivity of molecular imaging. The study demonstrated an appreciable difference of chelator influence for Ga-68 and In-111.
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| 10. |
- Tolmachev, Vladimir, et al.
(author)
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Comparative Evaluation of Anti-HER2 Affibody Molecules Labeled with Cu-64 Using NOTA and NODAGA
- 2017
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In: Contrast Media & Molecular Imaging. - : WILEY-HINDAWI. - 1555-4309 .- 1555-4317. ; , s. 1-12
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Journal article (peer-reviewed)abstract
- Imaging using affi body molecules enables discrimination between breast cancer metastases with high and low expression of HER2, making appropriate therapy selection possible. This study aimed to evaluate if the longer half-life of Cu-64 (T-1/2 = 12.7h) would make Cu-64 a superior nuclide compared to Ga-68 for PET imaging of HER2 expression using affibody molecules. The synthetic ZHER2: S1 affibody molecule was conjugated with the chelators NOTA or NODAGA and labeled with Cu-64. The tumor-targeting properties of Cu-64-NOTA-ZHER2: S1 and Cu-64-NODAGA-ZHER2: S1 were evaluated and compared with the targeting properties of Ga-68-NODAGA-ZHER2: S1 in mice. Both 64 Cu-NOTA-ZHER2: S1 and Cu-64-NODAGA-ZHER2: S1 demonstrated specific targeting of HER2-expressing xenografts. At 2 h after injection of Cu-64-NOTA-ZHER2: S1, Cu-64-NODAGA-ZHER2: S1, and Ga-68-NODAGAZHER2: S1, tumor uptakes did not differ significantly. Renal uptake of Cu-64-labeled conjugateswas dramatically reduced at 6 and 24 h after injection. Notably, radioactivity uptake concomitantly increased in blood, lung, liver, spleen, and intestines, which resulted in decreased tumor-to-organ ratios compared to 2 h postinjection. Organ uptake was lower for Cu-64-NODAGA-ZHER2: S1. The most probable explanation for this biodistribution pattern was the release and redistribution of renal radiometabolites. In conclusion, monoamide derivatives of NOTA and NODAGA may be suboptimal chelators for radiocopper labeling of anti-HER2 affibody molecules and, possibly, other scaffold proteins with high renal uptake.
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