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Neutron Capture Therapy of Cancer: Nanoparticles and High Molecular Weight Boron Delivery Agents
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Gong Wu, Rolf F. Barth, Weilian Yang, Robert J. Lee, Werner Tjarks, Marina V. Backer, Joseph M. Backer
In the 1950s and early 1960s clinical trials of BNCT were carried out using boric acid and some of its derivatives as delivery agents. These simple chemical compounds had poor tumor retention, attained low T:Br ratios and were nonselective.26,27 Among the hundreds of low-molecular-weight (LMW) boron-containing compounds that were synthesized, two appeared to be promising. One, based on arylboronic acids,28 was (l)-4-dihydroxy-borylphenylalanine, referred to as boronophenylalanine or BPA (Figure 6.1, 1). The second, a polyhedral borane anion, was sodium mercaptoundecahydro-closo-dodecaborate,29 more commonly known as sodium borocaptate or BSH (2). These two compounds persisted longer in animal tumors compared with related molecules, attained T:Br and T:Bl boron ratios greater than 1 and had low toxicity. 10B-enriched BPA, complexed with fructose to improve its water solubility, and BSH, have been used clinically for BNCT of brain, as well as extracranial tumors. Although their selective accumulation in tumors is not ideal, the safety of these two drugs following intravenous (i.v.) administration has been well established.30,31
Icosahedral boron clusters as modifying entities for biomolecules
Published in Expert Opinion on Biological Therapy, 2018
Tomasz M. Goszczyński, Krzysztof Fink, Janusz Boratyński
Our studies [19] on interactions with serum albumin encompassed the three types of boron clusters most commonly used in medicinal chemistry: dodecaborate anion, closo-carboranes, and metallacarboranes. Among the studied boron clusters and their derivatives, metallacarboranes and carboranes showed specific interaction with one of the binding clefts of albumin, while we observed no such interaction for dodecaborate anions. The observed strength of boron cluster interactions with albumin decreases in order: metallacarboranes [M(C2B9H11)2]− > carboranes (C2B10H12) ≫ dodecaborate [B12H12]2-.
Accelerator-based boron neutron capture therapy for malignant glioma: a pilot neutron irradiation study using boron phenylalanine, sodium borocaptate and liposomal borocaptate with a heterotopic U87 glioblastoma model in SCID mice
Published in International Journal of Radiation Biology, 2020
Evgenii Zavjalov, Alexander Zaboronok, Vladimir Kanygin, Anna Kasatova, Aleksandr Kichigin, Rinat Mukhamadiyarov, Ivan Razumov, Tatiana Sycheva, Bryan J. Mathis, Sakura Eri B. Maezono, Akira Matsumura, Sergey Taskaev
Advanced liposomal delivery studied by different BNCT scientific groups has also shown the increase in the tumor boron concentration compared to non-liposomal compounds. Maruyama et al. (2004) studied BSH-containing transferrin (TF)-conjugated polyethyleneglycol liposomes that could maintain tumor boron concentration over 30 ppm for at least 72 h after injection. This treatment was superior to PEG liposomes, bare liposomes and free BSH, resulting in tumor growth suppression and improved long-term survival of Colon 26 tumor-bearing mice after tail vein injections at 5 and 20 mg 10B/kg before nuclear reactor-based irradiation with 2 × 1012 neutrons/cm2 for 37 min. Nakamura (2008) showed boron concentrations of 8.8 ppm in tumor tissue 30 h after tail vein injection of BSH-liposomes in EMT6 tumor bearing BALB/c mice with higher tumor boron concentrations after i.v. administration of more advanced liposome-based compounds. Kueffer et al. (2013) studied unilamellar liposomes, developed using an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine that incorporate Na3[1-(2′-B10H9)-2-NH3B10H8] in the aqueous interior and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer. After two identical tail vein injections given 24 h apart in female BALB/c mice bearing flank EMT6 tumors, tumor boron levels exceeded 67 µg/g in tumors 54 h after the initial injection, showing significant suppression of tumor growth over control mice without liposome injection after irradiation with 1.6 × 1012 thermal neutrons/cm2 for 30 min. Spermidinium closo-dodecaborate-encapsulating liposomes were developed by Tachikawa et al. (2014) and showed maximum mouse Colon 26 tumor boron concentrations of 202.7 and 82.4 ppm achieved 36 h after tail vein injection at doses of 100 and 30 mg 10B/kg, respectively. This was superior to Na2BSH- and Na2[B12H11NH3]-encapsulating liposomes in tumor growth control and animal survival after irradiation with 1.3–2.2 × 1012 neutrons/cm2 for 50 min at a nuclear reactor.