The Combination Therapy Effects on Brain Tumor Cells and the Transplanted Mice Incorporated as a New Radio-photosensitizer and by Laser Light and Xrays (Hard- & Ionized-X-rays and Thermal Neutron Beam) in the Radiation Field

<p>It is widely known that thermal neutron beams for nuclear reactors, cyclotron or synchrotron radiation technology have made remarkable progress in the last 50 years, and that they are being constructed all over Japan and used for cancer irradiation treatment. Since the problems of cancer specificity and cancer recurrence have not been sufficiently resolved so far, synchrotron irradiation is not yet fully adopted as a new cancer treatment method. In order to solve the problem of cancer specificity and cancer recurrence, we applied it as a means to utilize and solve the cancer selectivity of porphyrin rings and evaluated the sensitization of these radiation sources.</p><p>¹⁰B decarbonate, a scavenger for thermal neutrons, and a derivative of porphyrin (Compound-B: CB) of Chlorin-E6 derivative were also used as sensitizers for these synchrotron and laser beams.</p><p>First, the photosensitizing efficiency of CB in Photodynamic Therapy (PDT) was compared with that of standard methylene blue (MB) and Laserfrin (Talaporfin Sodium) for clinical use. As a result, it was found that approximately 12–35% of photosensitivity can be expected compared to MB and conventional clinical photosensitizers.</p><p>Next, in order to verify the sensitization of CB to thermal neutron beams, proton beams, and carbon beam irradiation, C6 brain tumor cultured cells or transplanted mice to which CB was administered were used, and thermal neutron beams were used jointly in Research Reactor Institute of Kyoto University (KUR) and carbon beam microbeams were performed at the Atomic Energy Agency Takasaki Quantum Application of the research institute in vivo system, respectively. Furthermore, synchrotron proton beams were performed at the Wakasa Wan Research Center, the carbon beams were performed at National Institute of Radiological Sciences, and relatively higher-energy X-rays (>75 keV) were examined at the RI Center of the University of Fukui School of Medicine in vivo system, after application for joint use machine time, and the irradiation effects were examined each time, respectively.</p><p>As a result, the sensitization effect of CB was confirmed under different irradiation sources and conditions. Furthermore, a synergistic anti-tumor effect was obtained by the additional treatment of combined laser irradiation of photodynamic therapy (PDT), which has been continuously studied. Tumor recurrence could be effectively prevented, and in some cases, the tumors regressed and disappeared.</p><p>Therefore, the dual-use sensitizer molecule CB solves the problem of cancer recurrence through its cancer specificity, its sensitizing effect not only on thermal neutron beams but also on synchrotron and cyclotron radiation such as proton beams and carbon beams, and the synergistic effect of combined treatment with PDT.</p><p>As a result, the application of CB can be fully adopted as a new coping method (or therapeutic method) for synchrotron radiation to be effective. As a method of realization, it is conceivable to carry a compact semiconductor laser to a treatment facility for BNCT, proton beams, carbon beams, and use PDT in combination after the irradiations.</p>