| 1. |
- Carlsson, Jörgen, 1944-, et al.
(författare)
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Targeted Radionuclide Tumor Therapy : Biological Aspects
- 2008
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- The last three decades have provided opportunities to explore the potential of treating malignant diseases with antibodies or other targeting molecules labelled with nuclides. While considerable advances have been reported, there is still a significant amount of work left to accomplish before our ambitions can be achieved. It now seems timely to review the accomplishments achieved to date and to clarify the challenges that remain. The choice of radionuclide, the conjugation procedure employed, and the selection of suitable targets were early issues that were faced by our field that still persist, however we can now tackle these obstacles with significantly better insight. The expanding array of new targeting molecules (recombinant antibodies, peptides and agents based upon alternate scaffolds) may increase the therapeutic efficacy or even modify the radiation sensitivity of the targeted tumor cell. The title of this book “Targeted Radionuclide Tumour Therapy – Biological Aspects” was selected to reinforce the concept that a major focus of this volume was devoted to understanding the biological effects of targeting and radiation. These important issues have not previously been the primary focus in this context. Furthermore, our rapidly expanding knowledge of different types of cell death and the increasingly likely existence of cancer stem cells suggests to us that even more efficient approaches in targeting might be possible in the future. The development of targeted therapy is a true multidisciplinary enterprise involving physician scientists from the fields of nuclear medicine, radiation therapy, diagnostic radiology, surgery, gynaecology, pathology and medical oncology/haematology. It also involves many preclinical scientists working with experimental animal models, immunochemistry, recombinant antibody technologies, radiochemistry, radiation physics (dosimetry) and basic cell biology including the study of cell signalling pathways and the mechanisms of cellular death. Certainly several challenges remain in bringing targeted therapy into mainstream of treatment modalities, but in many of the chapters significant improvements in targeting efficiency are observed and may indicate future efficacy and acceptance, maybe not as a single treatment modality, but in combination with other strategies. It is the ambition of the editors to enable, with this volume, deeper insights in the process of improving targeted therapy for this diverse group of scientists. Clearly, some of the obstacles to gaining wider clinical acceptance might partly be related to this necessity of multidisciplinary collaborations. A number of disciplines, many of them mentioned above, have to both collaborate and coordinate with each other in order to control the chain of judgement necessary for the treatment of each patient. All these requirements may not always be available or easy to accomplish. This is a management paradigm shift, which usually would take some time. However, we hope that the chapters in this book will convince you, the reader, that a critical mass of knowledge regarding how to effectively use targeted radionuclide therapy has been accumulated. We believe, and hope that you will agree, that the time now has come when targeted therapy can soon be added to standard oncology treatment regimens.
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| 2. |
- Steffen, Ann-Charlott, et al.
(författare)
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In vitro characterization of a bivalent anti-HER-2 affibody with potential for radionuclide-based diagnostics
- 2005
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Ingår i: Cancer Biotherapy and Radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 20:3, s. 239-248
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Tidskriftsartikel (refereegranskat)abstract
- The 185 kDa transmembrane glycoprotein human epidermal growth factor receptor 2 (HER-2) (p185/neu, c-ErbB-2) is overexpressed in breast and ovarian cancers. Overexpression in breast cancer correlates with poor patient prognosis, and visualization of HER-2 expression might provide valuable diagnostic information influencing patient management. We have previously described the generation of a new type of affinity ligand, a 58-amino-acid affibody (Z(HER2:4)) with specific binding to HER-2. In order to benefit from avidity effects, we have created a bivalent form of the affibody ligand, (Z(HER2:4))2. The monovalent and bivalent ligands were compared in various assays. The new bivalent affibody has a molecular weight of 15.6 kDa and an apparent affinity (K(D)) against HER-2 of 3 nM. After radioiodination, using the linker molecule N-succinimidyl p-(trimethylstannyl) benzoate (SPMB), in vitro binding assays showed specific binding to HER-2 overexpressing cells. Internalization of 125I was shown after delivery with both the monovalent and the bivalent affibody. The cellular retention of 125I was longer after delivery with the bivalent affibody when compared to delivery with the monovalent affibody. With approximately the same affinity as the monoclonal antibody trastuzumab (Herceptin) but only one tenth of the size, this new bivalent molecule is a promising candidate for radionuclide-based detection of HER-2 expression in tumors. 125I was used in this study as a surrogate marker for the diagnostically relevant radioisotopes 123I for single photon emission computed tomography (SPECT)/gamma-camera imaging and 124I for positron emission tomography (PET).
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| 3. |
- Sundberg, Åsa Liljegren, 1974-
(författare)
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Tumour Targeting Using Radiolabelled EGF Conjugates : Preclinical Studies
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tumour targeted radiotherapy is an appealing approach for treatment of disseminated tumour cells. A targeting agent that specifically binds to a structure on tumour cells is then used to transport therapeutically relevant radionuclides. The epidermal growth factor receptor, EGFR, is overexpressed on tumour cells in several malignancies, e.g. highly malignant gliomas. In this thesis, three types of radiolabelled EGF-conjugates, aimed for targeting to EGFR-expressing tumour cells, were developed and studied: EGF-dextran labelled with 125I, EGF labelled with 211At, and two EGF-chelates, DTPA-EGF and Bz-DTPA-EGF, labelled with the radioactive metals 111In and 177Lu. The targeting properties of radioiodinated EGF-dextran were first studied in cultured glioma cells. Radioiodine coupled to the dextran part of EGF-dextran was retained in cells appreciably longer than radioiodine coupled to EGF. This can give about 100 times increased radiation dose to tumour cells.Targeting with 211At-EGF was investigated in combination with the tyrosine kinase inhibitor gefitinib (Iressa™, ZD1839). The uptake of 211At-EGF in EGFR-expressing tumour cells increased with increasing gefitinib concentrations. This was the case for both gefitinib-resistant and gefitinib-sensitive cell lines. The effect of the combined treatment on cell survival, however, differed between the cell lines in an unexpected way. In gefitinib resistant cells, combined treatment decreased cell survival approximately 3.5 times relative to 211At-EGF treatment alone. In gefitinib sensitive cells, however, combined treatment increased the cell survival (i.e. a protective effect).The EGF-chelates studied ([111In]DTPA-EGF, [111In]Bz-DTPA-EGF and [177Lu]Bz-DTPA-EGF) all bound specifically with high affinity (Kd≈2 nM) to EGFR on cultured glioma cells. They were internalised after binding, and the cellular retention of radionuclides was high (60% remained after 45 h). A biodistribution study in mice showed that liver and kidneys accumulated a majority of the radioactivity. The EGF-chelates bound EGFR specifically also in vivo. A tumour-to-blood ratio of 25 was achieved in a preliminary study.
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| 4. |
- Wikman, Maria, et al.
(författare)
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Selection and characterization of HER2/neu-binding affibody ligands
- 2004
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134. ; 17:5, s. 455-462
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Tidskriftsartikel (refereegranskat)abstract
- Affibody (affibody) ligands that are specific for the extracellular domain of human epidermal growth factor receptor 2 (HER2/neu) have been selected by phage display technology from a combinatorial protein library based on the 58 amino acid residue staphylococcal protein A-derived Z domain. The predominant variants from the phage selection were produced in Escherichia coli, purified by affinity chromatography, and characterized by biosensor analyses. Two affibody variants were shown to selectively bind to the extracellular domain of HER2/neu (HER2-ECD), but not to control proteins. One of the variants, denoted His6-ZHER2/neu:4, was demonstrated to bind with nanomolar affinity (approximately 50 nM) to the HER2-ECD molecule at a different site than the monoclonal antibody trastuzumab. Furthermore, radiolabeled His6-ZHER2/neu:4 affibody showed specific binding to native HER2/neu, overexpressed on the SKBR-3 tumor cell line. Such affibody ligands might be considered in tumor targeting applications for radionuclide diagnostics and therapy of adenocarcinomas such as breast and ovarian cancers.
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