| 1. |
- Bruskin, Alexander, et al.
(författare)
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Radiobromination of monoclonal antibody using potassium [76Br] (4 isothiocyanatobenzyl-ammonio)-bromo-decahydro-closo-dodecaborate (Bromo-DABI)
- 2004
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Ingår i: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 31:2, s. 205-11
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Tidskriftsartikel (refereegranskat)abstract
- The use of charged linkers in attaching radiohalogens to tumor-seeking biomolecules may improve intracellular retention of the radioactive label after internalization and degradation of targeting proteins. Derivatives of polyhedral boron clusters, such as closo-dodecaborate (2-) anion, might be possible charged linkers. In this study, a bifunctional derivative of closo-dodecaborate, (4-isothiocyanatobenzyl-ammonio)-undecahydro-closo-dodecaborate (DABI) was labeled with positron-emitting nuclide (76)Br (T 1/2 = 16.2 h) and coupled to anti-HER2/neu humanized antibody Trastuzumab. The overall labeling yield at optimized conditions was 80.7 +/- 0.6%. The label was proven to be stable in vitro in physiological and a set of denaturing conditions. The labeled antibody retained its capacity to bind to HER-2/neu antigen expressing cells. The results of the study demonstrated feasibility for using derivatives of closo-dodecaborate in indirect labeling of antibodies for radioimmunoPET.
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| 2. |
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| 3. |
- Lundqvist, Hans, et al.
(författare)
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Positron emission tomography and radioimmunotargeting : general aspects
- 1999
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Ingår i: Acta Oncologica. - 0284-186X .- 1651-226X. ; 38:3, s. 335-341
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Tidskriftsartikel (refereegranskat)abstract
- To optimize radioimmunotherapy, in vivo information on individual patients, such as radionuclide uptake, kinetics, metabolic patterns and optimal administration methods, is important. An overriding problem is to determine accurately the absorbed dose in the target organ as well as critical organs. Positron Emission Tomography (PET) is a superior technique to quantify regional kinetics in vivo with a spatial resolution better than 1 cm3 and a temporal resolution better than 10 s. However, target molecules often have distribution times of several hours to days. Conventional PET nuclides are not applicable and alternative positron-emitting nuclides with matching half-lives and with suitable labelling properties are thus necessary. Over many years we have systematically developed convenient production methods and labelling techniques of suitable positron nuclides, such as 110In(T(1/2) = 1.15 h), 86Y(T(1/2) = 14 h), 76Br(T(1/2) = 16 h) and 124I(T(1/2) = 4 days). 'Dose planning' can be done, for example, with 86Y- or 124I-labelled ligands before therapy, and 90Y- and 131I-labelled analogues and double-labelling, e.g. with a 86Y/90Y-labelled ligand, can be used to determine the true radioactivity integral from a pure beta-emitting nuclide. The usefulness of these techniques was demonstrated in animal and patient studies by halogen-labelled MAbs and EGF-dextran conjugates and peptides chelated with metal ions.
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| 4. |
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| 5. |
- Sundberg, Åsa Liljegren, et al.
(författare)
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[111In]Bz-DTPA-hEGF : Preparation and in vitro characterization of a potential anti-glioblastoma targeting agent
- 2003
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 18:4, s. 643-54
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Tidskriftsartikel (refereegranskat)abstract
- The overexpression of epidermal growth factor receptors, EGFR, in glioblastomas is well documented. Hence, the EGFR can be used as target structure for a specific targeting of glioblastomas. Both radiolabeled anti-EGFR antibodies and the natural ligand EGF are candidate agents for targeting. However, EGF, which has a rather low molecular weight (6 kDa), might have better tissue penetration properties through both normal tissue and tumors in comparison with anti-EGF antibodies and their fragments. The aim of this study was to prepare and evaluate in vitro an EGF-based antiglioma conjugate with residualizing label. Human recombinant EGF (hEGF) was coupled to isothiocyanate-benzyl-DTPA. The conjugate was purified from unreacted chelator using solid-phase extraction and labeled with (111)In. The labeling yield was 87% +/- 7%. The label was reasonably stable; the transchelation of (111)In to serum proteins was about 5% after incubation at 37 degrees C during 24 hours. The obtained [(111)In]benzyl-DTPA-hEGF conjugate was characterized in vitro using the EGFR expressing glioma cell line U343MGaCl2:6. The binding affinity, internalization, and retention of the conjugate were studied. The conjugate had receptor specific binding and the radioactivity was quickly internalized. The intracellular retention of radioactivity after interrupted incubation with conjugate was 71% +/- 1% and 59% +/- 1.5% at 24 and 45 hours, respectively. The dissociation constant was estimated to 2.0 nM. The results indicate that [(111)In]benzyl-DTPA-hEGF is a potential candidate for targeting glioblastoma cells, possibly using locoregional injection.
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| 6. |
- Sundberg, Åsa Liljegren, et al.
(författare)
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[177Lu]Bz-DTPA-EGF : Preclinical characterization of a potential radionuclide targeting agent against glioma
- 2004
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 19:2, s. 195-204
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Tidskriftsartikel (refereegranskat)abstract
- Patients with glioblastoma multiforme have a poor prognosis due to recurrences originating from spread cells. The use of radionuclide targeting might increase the chance of inactivating single tumor cells with minimal damage to surrounding healthy tissue. As a target, overexpressed epidermal growth factor receptors (EGFR) may be used. A natural ligand to EGFR, the epidermal growth factor (EGF) is an attractive targeting agent due to its low molecular weight (6 kDa) and high affinity for EGFR. 177Lu (T(1/2) = 6.7 days) is a radionuclide well suited for treatment of small tumor cell clusters, since it emits relatively low-energy beta particles. The goal of this study was to prepare and preclinically evaluate both in vitro and in vivo the [177Lu]Bz-DTPA-EGF conjugate. The conjugate was characterized in vitro for its cell-binding properties, and in vivo for its pharmacokinetics and ability to target EGFR. [177Lu]Bz-DTPA-EGF bound to cultured U343 glioblastoma cells with an affinity of 1.9 nM. Interaction with EGFR led to rapid internalization, and more than 70% of the cell-associated radioactivity was internalized after 30 minutes of incubation. The retention of radioactivity was good, with more than 65% of the 177Lu still cell-associated after 2 days. Biodistribution studies of i.v. injected [177Lu]Bz-DTPA-EGF in NMRI mice demonstrated a rapid blood clearance. Most of the radioactivity was found in the liver and kidneys. The liver uptake was receptor-mediated, since it could be significantly reduced by preinjection of unlabeled EGF. In conclusion, [177Lu]Bz-DTPA-EGF seems to be a promising candidate for locoregional treatment of glioblastoma due to its high binding affinity, low molecular weight, and ability to target EGFR in vivo.
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| 7. |
- Tolmachev, Vladimir, et al.
(författare)
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Comparative biodistribution of potential anti-glioblastoma conjugates [111In]DTPA-hEGF and [111In]Bz-DTPA-hEGF in normal mice
- 2004
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 19:4, s. 491-501
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Tidskriftsartikel (refereegranskat)abstract
- EGF-receptors (EGFR) are overexpressed in gliomas, as well as in tumors of breast, lung, and urinary bladder. For this reason, EGFR may be an attractive target for both visualization and therapy of malignant tumors using radioactive nuclides. Natural ligand of EGFR, epidermal growth factor (EGF) is a small 53-amino-acid protein. Low molecular weight of EGF may enable better intratumoral penetration in comparison to antibodies. [111In]DTPA-EGF was proposed for the targeting of glioblastoma and breast cancer, and its tumor-seeking properties were confirmed in animal studies. The aim of this study was to evaluate how the substitution of heptadentate DTPA for octadentate benzyl-DTPA (Bz-DTPA) effects the biodistribution of indium-labeled human EGF (hEGF) in normal NMRI mice. [111In]DTPA-hEGF and [111In]Bz-DTPA-hEGF, obtained by the coupling of ITC-benzyl-DTPA to hEGF, were injected into the tail vein. At 0.5, 1, 4, and 24 hours postinjection, the animals were sacrificed, and radioactivity in different organs was measured. The blood clearance of both conjugates was fast. The uptake of both conjugates in the liver, spleen, stomach, pancreas, intestines, and submaxillary gland was most likely receptor-mediated. The uptake in a majority of organs was similar. However, indium uptake in the case of [111In]DTPA-hEGF was significantly higher in the kidneys and bones. In conclusion, [111In]Bz-DTPA-hEGF seems to have more favourable in vivo distribution in comparison to [111In]DTPA-hEGF.
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| 8. |
- Tolmachev, Vladimir, et al.
(författare)
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Preparation, radioiodination, and in vitro evaluation of a nido-carborane-dextran conjugate, a potential residualizing label for tumor targeting proteins and peptides
- 2004
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - 0236-5731 .- 1588-2780. ; 261:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- Polysaccharides are not degradable by proteolytic enzymes in lysosomes and do not diffuse through cellular membranes. Thus, attached to an internalizing, targeting protein, such polysaccharide linkers, will remain intracellularly after protein degradation. They can be labeled with halogens and provide then a so called residualizing label. Such an approach improves tumor-to-non-tumor radioactivity ratio and, consequently, the results of radionuclide diagnostics and therapy. In this study we present a new approach to obtain a stable halogenation of the polysaccharide dextran using 7-(3-amino-propyl)-7,8-dicarba-nido-undecaborate (-) (ANC). Dextran T10 was partially oxidized by metaperiodate, and ANC was coupled to dextran by reductive amination. The conjugate was then labeled with 125I using either Chloramine-T or IodoGen as oxidants. Labeling efficiency was 69-85%. Stability of the label was evaluated in rat liver homogenates. Under these conditions, the ANC-dextran conjugate was found to be more stable than labeled albumin, which was used as a control protein.
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| 9. |
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| 10. |
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