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The development of novel, tumor-selective and boron-rich compounds as potential agents for use in boron neutron capture therapy (BNCT) represents a very important field in cancer treatment by radiation therapy. Here, we report the design and synthesis of two promising compounds that combine meta-carborane, a water-soluble monosaccharide and a linking unit, namely glycine or ethylenediamine, for facile coupling with various tumor-selective biomolecules bearing a free amino or carboxylic acid group. In this work, coupling experiments with two selected biomolecules, a coumarin derivative and folic acid, were included. The task of every component in this approach was carefully chosen: the carborane moiety supplies ten boron atoms, which is a tenfold increase in boron content compared to the l-boronophenylalanine (l-BPA) presently used in BNCT; the sugar moiety compensates for the hydrophobic character of the carborane; the linking unit, depending on the chosen biomolecule, acts as the connection between the tumor-selective component and the boron-rich moiety; and the respective tumor-selective biomolecule provides the necessary selectivity. This approach makes it possible to develop a modular and feasible strategy for the synthesis of readily obtainable boron-rich agents with optimized properties for potential applications in BNCT.

Specifically addressing cell surface molecules on cancer cells facilitates targeted cancer therapies that offer the potential to selectively destroy malignant cells, while sparing healthy tissue. Thus, undesired side-effects in tumor patients are highly reduced. Peptide-binding receptors are frequently overexpressed on cancer cells and therefore promising targets for selective tumor therapy. In this review, peptide-binding receptors for anti-cancer drug delivery are summarized with a focus on peptide ligands as delivery agents. In the first part, some of the most studied peptide-binding receptors are presented, and the ghrelin receptor and the Y1 receptor are introduced as more recent targets for cancer therapy. Furthermore, nonpeptidic small molecules for receptor targeting on cancer cells are outlined. In the second part, peptide conjugates for the delivery of therapeutic cargos in cancer therapy are described. The essential properties of receptor-targeting peptides are specified, and recent developments in the fields of classical peptide-drug conjugates with toxic agents, radiolabeled peptides for radionuclide therapy, and boronated peptides for boron neutron capture therapy are presented.

<p>Physico-chemical characterisation of structure and stability of liposomes intended for drug delivery is the central issue in this thesis. In addition, targeted liposomes to be used in boron neutron capture therapy (BNCT) were developed.</p><p>Lysolipids and fatty acids are products formed upon hydrolysis of PC-lipids. The aggregate structure formed upon mixing lysolipids, fatty acids and EPC were characterised by means of cryo-TEM. A relatively monodisperse population of unilamellar liposomes was detected in mixtures containing equimolar concentration of the three components. </p><p>The interactions between alternative steric stabilisers (PEO-PPO-PEO copolymers) and conventional PC-and pH-sensitive PE-liposomes were investigated. Whereas the PE-liposomes could be stabilised by the PEO-PPO-PEO copolymers, the PC-liposomes showed an enhanced permeability concomitant with the PEO-PPO-PEO adsorption.</p><p>Permeability effects induced by different PEG-stabilisers on EPC liposomes were shown to be dependent on the length of the PEG chain but also on the linkage used to connect the PEG polymer with the hydrophobic membrane anchor.</p><p>An efficient drug delivery requires, in most cases, an accumulation of the drug in the cell cytoplasm. The mechanism behind cytosolic drug delivery from pH-sensitive liposomes was investigated. The results suggest that a destabilisation of the endosome membrane, due to an incorporation of non-lamellar forming lipids, may allow the drug to be released. </p><p>Furthermore, sterically stabilised liposomes intended for targeted BNCT have been characterised and optimised concerning loading and retention of boronated drugs. </p>

Physico-chemical characterisation of structure and stability of liposomes intended for drug delivery is the central issue in this thesis. In addition, targeted liposomes to be used in boron neutron capture therapy (BNCT) were developed. Lysolipids and fatty acids are products formed upon hydrolysis of PC-lipids. The aggregate structure formed upon mixing lysolipids, fatty acids and EPC were characterised by means of cryo-TEM. A relatively monodisperse population of unilamellar liposomes was detected in mixtures containing equimolar concentration of the three components. The interactions between alternative steric stabilisers (PEO-PPO-PEO copolymers) and conventional PC-and pH-sensitive PE-liposomes were investigated. Whereas the PE-liposomes could be stabilised by the PEO-PPO-PEO copolymers, the PC-liposomes showed an enhanced permeability concomitant with the PEO-PPO-PEO adsorption. Permeability effects induced by different PEG-stabilisers on EPC liposomes were shown to be dependent on the length of the PEG chain but also on the linkage used to connect the PEG polymer with the hydrophobic membrane anchor. An efficient drug delivery requires, in most cases, an accumulation of the drug in the cell cytoplasm. The mechanism behind cytosolic drug delivery from pH-sensitive liposomes was investigated. The results suggest that a destabilisation of the endosome membrane, due to an incorporation of non-lamellar forming lipids, may allow the drug to be released. Furthermore, sterically stabilised liposomes intended for targeted BNCT have been characterised and optimised concerning loading and retention of boronated drugs.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17790号 / 工博第3769号 / 新制||工||1576(附属図書館) / 30597 / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 伊藤 秋男, 教授 神野 郁夫, 准教授 櫻井 良憲 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19897号 / 工博第4213号 / 新制||工||1651(附属図書館) / 32974 / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 神野 郁夫, 准教授 田﨑 誠司, 准教授 櫻井 良憲 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually: 10B and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount of 10B in the tumor but also on the organs at risk. It is not yet possible to determine the 10B concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure the 10B concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake of 10B from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine the 10B concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach.

<p>This thesis describes the use of copper and palladium to mediate transformations of carboranes, especially <i>p</i>-carborane.</p><p>1-(1-<i>p</i>-carboranyl)-<i>N</i>-methyl-<i>N</i>-(2-butyl)-3-isoquinolinecarboxamide, a carborane containing analogue of the peripheral benzodiazepine receptor (PBR) ligand PK11195, has been synthesised. A key step in the reaction is the copper (I) mediated coupling of p-carborane with ethyl 1-bromo-isoquinoline-3-carboxylate. </p><p><i>p</i>-Carborane has been arylated on the 2-<i>B</i>-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I-<i>p</i>-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeO-C₆H₄-, 3-CH₃CONH-C₆H₄-, 4-NC-C₆H₄-, 3-NO₂-C₆H₄-], gave the corresponding 2-aryl-<i>p</i>-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd₂(dba)₃–dppb system. Under the same conditions, the boron-boron bond forming reaction of two <i>p</i>-carboranylboronic esters (2-[(pinacolato)boron]-<i>p</i>-carborane and 2-[(neopentyl glycolato)boron]-p-carborane) was also shown feasible.</p><p><i>p</i>-Carborane has been vinylated on the 2-<i>B</i>-atom in high yields by use of the Heck reaction. The coupling between 2-I-<i>p</i>-carborane and various styrenes [4-H-, 4-C₆H₄-, 4-Cl , 4-Br-, 4-NO₂-, 4-CH3O- and 4 CH₃ ] resulted in the formation of the corresponding<i>trans</i>-β-(2-<i>B</i>-<i>p</i>-carboranyl) styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann´s catalyst. The reaction was shown to proceed at higher rate with electron rich than with electron deficient olefins.</p><p>The feasibility of palladium-catalysed isotopic exchange of an iodinated closo-carborane with a radioisotope of iodine has been studied. 2-I-<i>p</i>-carborane was selected as a model compound. It was shown, that such isotopic exchange is possible and provides a high yield (83 ± 4.2 %) during 40 min long reaction. The reaction conditions were optimised, and it was demonstrated that presence of the tetra n-butylammonium hydrogensulphate is important in order to stabilise catalyst and provide reproducibility of labelling. In this work we have modified the methodology and extended the application to a wider range of iodinated carboranes. By the use of Herrmann’s catalyst in toluene at 100 °C this [¹²⁵I]-iodide labelling could be improved and extended. 2-I-<i>p</i>- 9-I-<i>m</i>-, 9-I-<i>o</i>-, 3-I-<i>o</i>-carborane, 1-phenyl-3-I-<i>o</i>-carborane and 1,2-diphenyl-3-I-<i>o</i>-carborane could be [¹²⁵I]-iodide labelled in high to excellent yields within 5 minutes.This reported palladium catalyzed radio-iodination of the uncharged closo-carboranes might find use in pharmacokinetic studies of carborane derivatives.</p>

This thesis describes the use of copper and palladium to mediate transformations of carboranes, especially p-carborane. 1-(1-p-carboranyl)-N-methyl-N-(2-butyl)-3-isoquinolinecarboxamide, a carborane containing analogue of the peripheral benzodiazepine receptor (PBR) ligand PK11195, has been synthesised. A key step in the reaction is the copper (I) mediated coupling of p-carborane with ethyl 1-bromo-isoquinoline-3-carboxylate. p-Carborane has been arylated on the 2-B-atom in high yields, using the Suzuki–Miyaura reaction. Thus the reaction between 2-I-p-carborane and various arylboronic acids [1-naphthyl-, phenyl-, 4-MeO-C6H4-, 3-CH3CONH-C6H4-, 4-NC-C6H4-, 3-NO2-C6H4-], gave the corresponding 2-aryl-p-carboranes in DME solution when reacted in the presence of cesium fluoride and the catalytic Pd2(dba)3–dppb system. Under the same conditions, the boron-boron bond forming reaction of two p-carboranylboronic esters (2-[(pinacolato)boron]-p-carborane and 2-[(neopentyl glycolato)boron]-p-carborane) was also shown feasible. p-Carborane has been vinylated on the 2-B-atom in high yields by use of the Heck reaction. The coupling between 2-I-p-carborane and various styrenes [4-H-, 4-C6H4-, 4-Cl , 4-Br-, 4-NO2-, 4-CH3O- and 4 CH3 ] resulted in the formation of the correspondingtrans-β-(2-B-p-carboranyl) styrene in DMF solution when reacted in the presence of silver phosphate and the palladacycle Herrmann´s catalyst. The reaction was shown to proceed at higher rate with electron rich than with electron deficient olefins. The feasibility of palladium-catalysed isotopic exchange of an iodinated closo-carborane with a radioisotope of iodine has been studied. 2-I-p-carborane was selected as a model compound. It was shown, that such isotopic exchange is possible and provides a high yield (83 ± 4.2 %) during 40 min long reaction. The reaction conditions were optimised, and it was demonstrated that presence of the tetra n-butylammonium hydrogensulphate is important in order to stabilise catalyst and provide reproducibility of labelling. In this work we have modified the methodology and extended the application to a wider range of iodinated carboranes. By the use of Herrmann’s catalyst in toluene at 100 °C this [125I]-iodide labelling could be improved and extended. 2-I-p- 9-I-m-, 9-I-o-, 3-I-o-carborane, 1-phenyl-3-I-o-carborane and 1,2-diphenyl-3-I-o-carborane could be [125I]-iodide labelled in high to excellent yields within 5 minutes.This reported palladium catalyzed radio-iodination of the uncharged closo-carboranes might find use in pharmacokinetic studies of carborane derivatives.