| 1. |
- Cheng, Junping, 1965-
(författare)
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Radioimmunotherapy in Experimental Head and Neck Squamous Cell Carcinoma : Tumour-targeting in vitro and in vivo
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radioimmunotherapy (RIT) has been shown to be a practicable way to treat head and neck squamous cell carcinoma. A specific antibody recognizes the charasteristic structure of tumour cells when loaded with cytotoxic agents (toxins, drugs, radionuclides, etc). But RIT kills not only tumour cells with attached radionuclides but also adjacent tumour cells due to the “cross fire effect”. To be efficacious, RIT depends closely on suitable monoclonal antibody, on the properties of the chosen radionuclides, and on a suitable labelling method for attaching radionuclide to antibody. In this study we initially used radionuclide-labelled cMAB U36, via linker DABI in order to improve the retention of radio-conjugates in the tumour cells. Improved retention is important because the longer the radionuclide remains in tumour cells, the more effective will the tumour cells be eradicated. In the investigation, both normal mice and HNSCC-bearing nude mice were used to compare our form of treatment against other radio-iodination methods. In the biodistribution study, normal mice showed that radioactive uptake in organs diminished with time, irrespectively of whether the conjugate was directly or indirectly labelled. But in thyroid, there was a tenfold greater accumulation of direct-labelled than of indirectly labelled conjugate.In tumour-bearing nude mice, by contrast, the results showed promising uptake of radioactivity, but little uptake in direct-labelled conjugate in thyroid. Significant differences were observed on comparing tumour: organ ratios between 131I-cMAb U36 vs. 125I-DABI-cMAb U36.In the present study, cMAb U36 labelled with 211Astatine was initially used to treat HNSCC in nude mice. The biodistribution of 211At-cMAb U36 did not reveal any significant difference between an antibody-blocked group and a non-blocked group. But it did highlight the characteristics of a successful targeting conjugate in HNSCC-bearing nude mice.In the subcutaneous therapy experiment, most of the treated tumours (n=18) had disappeared by the 26th day, in both U36-blocked and non-blocked groups. Treatment in the intravenous therapy experiment had also proved effective. In the antibody non-blocked group, the smallest tumour volume was 25 mm3 (average 111 mm3) vis-á-vis 65 mm3 (average 145 mm3) in the blocked group. None of tumours grew again following treatment.
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| 2. |
- Mume, Eskender, 1968-
(författare)
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Radiohalogenated Compounds for Tumor Targeting : Synthesis and Radiolabeling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the synthesis and radiohalogenation of compounds of potential use for tumor targeting. The first section describes the synthesis and radioiodination of DNA intercalating compounds. The compounds are derivatives of 9-aminoacridine, and the anthracyclins daunorubicin and doxorubicin. The precursor compounds were labeled with 125I (T1/2 = 60 days), which is an Auger emitting nuclide. 125I decaying in the close vicinity of DNA is known to have a much higher cell killing effect than 125I decaying in the cytoplasm and some of the labeled compounds prepared in this thesis are currently being tested for use in targeted radionuclide therapy for cancer. The second section describes the radiobromination of closo-carboranes by subjecting the corresponding iodinated compounds to palladium-catalyzed halogen exchange using [76Br]bromide. The 76Br isotope (T1/2 = 16.2 h) is a positron emitting nuclide that is suitable for PET studies. Via the halogen exchange reaction good to excellent radiochemical yields of radiobrominated closo-carboranes were obtained. The results of the present study may prove to be applicable to pharmacokinetic studies of carboranes and their derivatives. The third and final section describes the indirect radiobromination of the trastuzumab anti-HER2 monoclonal antibody and of the anti-HER2 Affibody by means of an “one-pot” procedure using N-succinimidyl-5-(tributylstannyl)-3-pyridinecarboxylate (SPC) and ((4-hydroxyphenyl)ethyl))maleimide (HPEM), respectively. It was found that SPC and HPEM can be efficiently radiobrominated and thereafter coupled to the antibody and Affibody, respectively. The labeled proteins retained their capacity to bind specifically to HER2 expressing SKOV-3 cells in vitro. Application of this method to 76Br might enable the use of PET in the detection of HER2 expression in breast, ovarian, and urinary bladder carcinomas.
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| 3. |
- Persson, Mikael, 1975-
(författare)
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Antibody Mediated Radionuclide Targeting of HER-2 for Cancer Diagnostics and Therapy : Preclinical Studies
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Targeted radionuclide therapy (TRT) holds great promise for the treatment of cancer. In TRT, radioactive nuclides are delivered specifically to tumours by molecules that recognise and bind to structures overexpressed by, or specific to, cancer cells. Human epidermal growth factor receptor like protein 2 (HER-2) is an oncogene product overexpressed in e.g. urological, breast, or ovarian cancers that have been correlated to poor prognosis and resistance to hormonal therapy. There is also evidence that tumour cells retain their HER-2 overexpression in metastases. Trastuzumab and pertuzumab are two humanised monoclonal antibodies targeting different parts of HER-2. This thesis describes the radiolabelling of these antibodies for use in TRT and diagnostics. The thesis also investigates possible methods for modifying uptake and retention of radioactivity delivered with antibodies binding to HER-2. Modification of the cellular retention of 125I by using polyhedral boron anion based linker molecules (DABI and NBI) is investigated, and it is shown that linking 125I to trastuzumab using DABI increases cellular accumulation of radioactivity by 33%. It is also shown that trastuzumab can be efficiently coupled to the positron emitter 76Br by using NBI. Furthermore, it is shown that cellular uptake of 125I can be modified by stimulating EGFR (HER-1) with EGF. When labelled with the alpha emitter 211At, trastuzumab could specifically kill cells in vitro. This cell killing effect could be prevented by saturating the receptors of the target cells with non-radiolabelled trastuzumab. Pertuzumab was radiolabelled with the low energy beta emitter 177Lu without losing affinity or immunocompetence. [177Lu]pertuzumab was specific to HER-2 in vitro and in vivo. This targeting conjugate was shown to increase median time to tumour progression in mice bearing xenografts of the radioresistant SKOV-3 cell line. In conclusion, antibodies against HER-2, especially pertuzumab radiolabelled with 177Lu, show promise as TRT agents.
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| 4. |
- Steffen, Ann-Charlott, 1977-
(författare)
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Radiolabeled HER-2 Binding Affibody Molecules for Tumor Targeting : Preclinical Studies
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Conventional cancer treatment based on radiotherapy or chemotherapy affects all dividing cells. By directing the therapy specifically to the tumor cells, normal cells can be spared. Tumor targeting molecules carrying a cytotoxic moiety is then an attractive approach.In this thesis, an affibody molecule with high affinity for the protein HER-2, that is strongly associated with aggressive forms of breast cancer, was selected. After radiolabeling with 125I, the affibody molecule, in monovalent and bivalent form, was tested in vitro in HER-2 overexpressing tumor cells and in transplanted tumors in mice.It was shown that the HER-2 targeting affibody molecule bound its target in a specific manner, both in vitro and in vivo. The small size of the affibody molecule resulted in fast clearance through the kidneys. An impressive tumor-to-blood ratio of 10 eight hours post injection was achieved and the tumors could easily be visualized in a gamma camera.The biologic effects of the bivalent affibody molecule and a monovalent affinity maturated version was measured and compared with the effects of the monoclonal antibody trastuzumab. It was found that although all molecules target the same protein, the effects differed greatly.The affibody molecule was also labeled with the alpha-emitting radionuclide 211At. Specific decrease in survival was seen in HER-2 overexpressing cells receiving the 211At labeled affibody molecule. The sensitivity to the treatment differed between cell lines, probably as a result of differences between the cell lines in internalization and nuclear size. The 211At labeled affibody molecules were also tested in vivo, where stability of the 211At label was a problem. To circumvent this problem, more stable conjugation chemistry was tested, as well as strategies to prevent uptake of released 211At by normal organs.This thesis describes the selection and optimization of affibody molecules for medical use for the first time.
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| 5. |
- Tran, Thuy, 1980-
(författare)
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Molecular Imaging of HER2 Expression using Synthetic Affibody Molecules : Design, Synthesis and Biological Evaluation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Molecular imaging is an emerging multidisciplinary field that addresses the visualisation of diseases at the cellular and molecular levels. This thesis focuses on the development of a synthetic Affibody molecule-based imaging tracer for the detection of HER2 expression in malignant tumours. Papers I-IV report the development of the HER2-specific Affibody molecule, ZHER2:342 by peptide synthesis and the use of different chelators attached to the N-terminus to allow 99mTc-labelling. Paper I described the optimisation of labelling of Affibody molecules using cysteine-based chelator sequences, in which the direct labelling method under alkaline conditions was the most suitable one. Papers II-IV report the development and optimisation of the in vivo properties of the HER2-specific Affibody molecule for high-contrast imaging. By using an array of mercaptoacetyl-based chelators, it was found that the substitution of a single amino acid in a 60 amino acid-long Affibody molecule can dramatically change the pharmacokinetics of the tracer. Strategic approaches that utilised hydrophilic amino acids, such as serine, glutamate and lysine, changed the excretion pathway from hepatobiliary to renal excretion. Problems with the high accumulation of radioactivity in the abdomen area and restricted imaging were resolved by the use of mercaptoacetyl-triglutamyl, maEEE or mercaptoacetyl-seryl-lysyl-seryl, maSKS chelators. Paper V reports the re-engineering of the HER2-specific Affibody molecule to provide a C-terminal SECG sequence using peptide synthesis. Incorporation of this sequence provided a multifunctional platform for labelling (with technetium or trivalent radiometals) and a flexible production route (recombinant or chemical synthesis). Combination of a serine, a glutamic acid and a thiol-bearing group in the chelating sequence reduced the renal accumulation of Affibody molecules. Altogether, the in vivo efficiency of Affibody molecules to target tumours and their biodistribution properties can be improved by strategic design and suitable chemistry. Hopefully, these observations will be applicable to other small peptide and protein scaffold-based tracers.
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| 6. |
- Winander, Cecilia, 1980-
(författare)
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Targeting Biological Systems by Organic Synthesis Methods - Cancer Cells and Proteins
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the design and synthesis of molecules with potential roles in biomedicine, with an emphasis on molecular recognition in complex biological environments. The first chapter describes the synthesis and evaluation of compounds for use in nuclide therapy. Carboranes are frequently used in the development of drugs for Boron Neutron Capture Therapy. New routes for monohydroxylation at the B and C atoms of p-carborane have been developed. The Suzuki-Miyaura reaction has been applied to the cross-coupling of bis(neopentyl glycolato)diboron or bis(pinacolato)diboron and 2-I-p-carborane. The synthesized derivatives are important intermediates in the synthesis of a number of potentially biologically active carborane-containing molecules.The DNA intercalator doxorubicin has been functionalized to enable 125I labelling. The aim of combining the DNA intercalator with 125I was to achieve high delivery of cytotoxic radiation to the nucleus. The DNA-binding ability and cellular uptake of the synthesized compounds have been evaluated. One of the compounds bound strongly to DNA and had similar cellular uptake as daunorubicin, which makes the compound very interesting for further biological evaluation.The second chapter describes the use of polypeptide conjugates to broaden our knowledge of molecular recognition. The polypeptides consist of 42 amino acids each and are designed to fold into helix-loop-helix motifs that dimerize due to their amphiphilic character. The polypeptides are combined with a variety of small organic molecules. The incorporation of small aromatic molecules to influence the structure and dynamics of a polypeptide has been investigated. By attaching a dansyl group to the side chain of a lysine residue, the dynamics of the protein’s hydrophobic core where affected to such a degree that a native-like fold was formed. The polypeptide conjugates have also been used to study the binding and recognition of native proteins. High-affinity binders for chitinases and acetylcholine esterase have been developed and evaluated.
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