MDPI AG Acta Medica Okayama 2673-8937 5 1 2025 The Early Response After Radiation Therapy on Three-Dimensional Oral Cancer Model Using Patient-Derived Cancer-Associated Fibroblasts 12 EN Izumi Yamamoto Neutron Therapy Research Center, Okayama University Kazuyo Igawa Neutron Therapy Research Center, Okayama University Natsuko Kondo Particle Radiation Oncology Center, Institute for Integrated Radiation and Nuclear Science, Kyoto University Yoshinori Sakurai Particle Radiation Oncology Center, Institute for Integrated Radiation and Nuclear Science, Kyoto University Atsushi Fujimura Department of Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kiyofumi Takabatake Department of Oral Pathology and Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Peng Huang Neutron Therapy Research Center, Okayama University Hiroyuki Michiue Neutron Therapy Research Center, Okayama University Soichiro Ibaragi Department of Oral and Maxillofacial Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kenji Izumi Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Background/Objectives: Cancer-associated fibroblasts (CAFs), which are an important component of the tumor microenvironment, have been reported to have an adverse effect on conventional radiotherapy. This study aims to elucidate the effects of CAFs in boron neutron capture therapy (BNCT) using a three-dimensional (3D) oral cancer model. Methods: Three-dimensional cancer models were fabricated using patient-derived CAFs or patient-derived normal oral fibroblasts (NOFs) and a human oral squamous cell carcinoma cell line. Each 3D cancer model was performed with either a conventional X-ray treatment or BNCT and additionally analyzed histomorphologically. Results: The 3D oral cancer-CAFs model demonstrated a greater depth of cancer cell invasion than the 3D oral cancer-NOFs model. Radiation therapy for the 3D oral cancer models indicated a trend for decreasing cancer cell invasion and cell number with dose dependence in both X-ray and BNCT. In comparison with X-rays, BNCT showed a consistent increase in the number of NOFs and a significant reduction in the number of CAFs. Conclusions: BNCT for the 3D oral cancer model was shown to be effective against cancer cells and CAFs but not against NOFs, indicating its usefulness as a minimally invasive treatment for advanced cancer. Furthermore, it is indicated that the 3D oral cancer-CAFs model is a valuable tool to evaluate cancer treatment and research, particularly in high-grade malignant tumors with invasion. No potential conflict of interest relevant to this article was reported.

MDPI AG Acta Medica Okayama 2227-9059 12 10 2024 Development and Characterization of a Three-Dimensional Organotypic In Vitro Oral Cancer Model with Four Co-Cultured Cell Types, Including Patient-Derived Cancer-Associated Fibroblasts 2373 EN Yuka Aizawa Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Kenta Haga Division of Reconstructive Surgery for Oral and Maxillofacial Region, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Nagako Yoshiba Department of Oral Health and Welfare, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Witsanu Yortchan Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Sho Takada Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Rintaro Tanaka Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Eriko Naito Division of Oral and Maxillofacial Surgery, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Tatsuya Abé Division of Oral Pathology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Satoshi Maruyama Division of Oral Pathology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Manabu Yamazaki Division of Oral Pathology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Jun-ichi Tanuma Division of Oral Pathology, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Kazuyo Igawa Neutron Therapy Research Center, Okayama University Kei Tomihara Division of Oral and Maxillofacial Surgery, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Shinsaku Togo Department of Respiratory Medicine, Graduate School of Medicine, Juntendo University Kenji Izumi Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Background/Objectives: Cancer organoids have emerged as a valuable tool of three-dimensional (3D) cell cultures to investigate tumor heterogeneity and predict tumor behavior and treatment response. We developed a 3D organotypic culture model of oral squamous cell carcinoma (OSCC) to recapitulate the tumor–stromal interface by co-culturing four cell types, including patient-derived cancer-associated fibroblasts (PD-CAFs). Methods: A stainless-steel ring was used twice to create the horizontal positioning of the cancer stroma (adjoining normal oral mucosa connective tissue) and the OSCC layer (surrounding normal oral mucosa epithelial layer). Combined with a structured bi-layered model of the epithelial component and the underlying stroma, this protocol enabled us to construct four distinct portions mimicking the oral cancer tissue arising in the oral mucosa. Results: In this model, α-smooth muscle actin-positive PD-CAFs were localized in close proximity to the OSCC layer, suggesting a crosstalk between them. Furthermore, a linear laminin-γ2 expression was lacking at the interface between the OSCC layer and the underlying stromal layer, indicating the loss of the basement membrane-like structure. Conclusions: Since the specific 3D architecture and polarity mimicking oral cancer in vivo provides a more accurate milieu of the tumor microenvironment (TME), it could be crucial in elucidating oral cancer TME. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2673-6284 12 2 2023 Development of the Follow-Up Human 3D Oral Cancer Model in Cancer Treatment 35 EN Kazuyo Igawa Neutron Therapy Research Center, Okayama University Kenji Izumi Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University Yoshinori Sakurai Institute for Integrated Radiation and Nuclear Science, Kyoto University As function preservation cancer therapy, targeted radiation therapies have been developed for the quality of life of cancer patients. However, preclinical animal studies evaluating the safety and efficacy of targeted radiation therapy is challenging from the viewpoints of animal welfare and animal protection, as well as the management of animal in radiation-controlled areas under the regulations. We fabricated the human 3D oral cancer model that considers the time axis of the follow up in cancer treatment. Therefore, in this study, the 3D model with human oral cancer cells and normal oral fibroblasts was treated based on clinical protocol. After cancer treatment, the histological findings of the 3D oral cancer model indicated the clinical correlation between tumor response and surrounding normal tissue. This 3D model has potential as a tool for preclinical studies alternative to animal studies. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 1347-9032 115 10 2024 Overcoming immunotherapy resistance and inducing abscopal effects with boron neutron immunotherapy (B-NIT) 3231 3247 EN Takuya Fujimoto Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Osamu Yamasaki Department of Dermatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Noriyuki Kanehira Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Hirokazu Matsushita Division of Translational Oncoimmunology, Aichi Cancer Center Research Institute Yoshinori Sakurai Institute for Integrated Radiation and Nuclear Science, Kyoto University Naoya Kenmotsu Department of Tumor Microenvironment, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Ryo Mizuta Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Natsuko Kondo Institute for Integrated Radiation and Nuclear Science, Kyoto University Takushi Takata Institute for Integrated Radiation and Nuclear Science, Kyoto University Mizuki Kitamatsu Faculty of Science and Engineering, Kindai University Kazuyo Igawa Neutron Therapy Research Center, Okayama University Atsushi Fujimura Neutron Therapy Research Center, Okayama University Yoshihiro Otani Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Makoto Shirakawa Neutron Therapy Research Center, Okayama University Kunitoshi Shigeyasu Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Fuminori Teraishi Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Yosuke Togashi Department of Tumor Microenvironment, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Minoru Suzuki Institute for Integrated Radiation and Nuclear Science, Kyoto University Toshiyoshi Fujiwara Department of Gastroenterological Surgery, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences Hiroyuki Michiue Neutron Therapy Research Center, Okayama University Immune checkpoint inhibitors (ICIs) are effective against many advanced malignancies. However, many patients are nonresponders to immunotherapy, and overcoming this resistance to treatment is important. Boron neutron capture therapy (BNCT) is a local chemoradiation therapy with the combination of boron drugs that accumulate selectively in cancer and the neutron irradiation of the cancer site. Here, we report the first boron neutron immunotherapy (B-NIT), combining BNCT and ICI immunotherapy, which was performed on a radioresistant and immunotherapy-resistant advanced-stage B16F10 melanoma mouse model. The BNCT group showed localized tumor suppression, but the anti-PD-1 antibody immunotherapy group did not show tumor suppression. Only the B-NIT group showed strong tumor growth inhibition at both BNCT-treated and shielded distant sites. Intratumoral CD8+ T-cell infiltration and serum high mobility group box 1 (HMGB1) levels were higher in the B-NIT group. Analysis of CD8(+) T cells in tumor-infiltrating lymphocytes (TILs) showed that CD62L- CD44(+) effector memory T cells and CD69(+) early-activated T cells were predominantly increased in the B-NIT group. Administration of CD8-depleting mAb to the B-NIT group completely suppressed the augmented therapeutic effects. This indicated that B-NIT has a potent immune-induced abscopal effect, directly destroying tumors with BNCT, inducing antigen-spreading effects, and protecting normal tissue. B-NIT, immunotherapy combined with BNCT, is the first treatment to overcome immunotherapy resistance in malignant melanoma. In the future, as its therapeutic efficacy is demonstrated not only in melanoma but also in other immunotherapy-resistant malignancies, B-NIT can become a new treatment candidate for advanced-stage cancers. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 2666-8319 9 2024 Radiation evaluation assay using a human three-dimensional oral cancer model for clinical radiation therapy. 100297 EN Lucie Sercombe Biomedical Engineering Department, Grenoble Institute of Technology Kazuyo Igawa Neutron Therapy Research Center, Okayama University Kenji Izumi Division of Biomimetics, Faculty of Dentistry & Graduate School of Medical and Dental Sciences, Niigata University With the development of various radiation -based cancer therapies, radiobiological evaluation methods instead of traditional clonogenic assays with monolayer single cell culture are required to bridge gaps in clinical data. Heterogeneity within cancer tissues is the reason for bridging the gap between basic and clinical research in cancer radiotherapy. To solve this problem, we investigated an evaluation assay using a three-dimensional (3D) model of cancer tissue. In this study, a 3D model consisting of tumor and stromal layers was used to compare and verify radiobiological effects with conventional two-dimensional (2D) methods. A significant difference in the response to radiation was observed between the 2D and 3D models. The relative number of cancer cells decreased with X-ray dose escalations in the 2D and 3D models. In contrast, the relative number of normal cells was quite different between the 2D and 3D models. Considering the ability of cells to recover from radiation-induced damage, the histological results of the 3D model were reflected in the clinical data. Histopathological analysis using a 3D model is a potential method for evaluating radiobiological effects on the tumor and tumor margins. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 2513-0390 6 7 2023 Particle and Heavy Ion Transport Code System‐Based Microdosimetry for the Development of Boron Agents for Boron Neutron Capture Therapy 2300163 EN Takafumi Shigehira Department of Cellular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tadashi Hanafusa Neutron Therapy Research Center, Okayama University Kazuyo Igawa Neutron Therapy Research Center, Okayama University Tomonari Kasai Neutron Therapy Research Center, Okayama University Shuichi Furuya Research Laboratory of Accelerator-Based BNCT system, Graduate School of Engineering Nagoya University Hisakazu Nishimori Department of Hematology and Oncology Okayama University Hospital Okayama Okayama 700–8558 Japan Yoshinobu Maeda Department of Hematology and Oncology, Okayama University Hospital Hiroyuki Michiue Neutron Therapy Research Center, Okayama University Atsushi Fujimura Department of Cellular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Boron neutron capture therapy (BNCT) is a radiation therapy that selectively kills cancer cells at the cellular level using the boron neutron capture reaction (BNCR) (10B(n.α)7Li). The amount of boron 10B delivers in boronophenylalanine (BPA)-BNCT to achieve anti-tumor effects is ≈15–40 ppm. The same is true for all boron drugs; however, whether the same amount of 10B is required for other boron drugs with different accumulation characteristics has not been intensively investigated. Therefore, herein, a virtual cell model with intracellular organelles is prepared, and the BPA equivalent dose concentration to the cell nucleus is analyzed using particle and heavy ion transport code system-based microdosimetry. Additionally, the intranuclear minimal region (IMR) is set as a reference for the concept of the intranuclear domain in the microdosimetric kinetic model, and the BPA equivalent dose concentration to the IMR is estimated. The required boron delivery dose greatly varies depending on the dose assessment based on the accumulation characteristics of boron agents in intracellular organelles. Evaluation of the BNCR effect according to the accumulation characteristics without being influenced by the specified value of 15–40 ppm is recommended. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 19917902 2021 Prevention and early management of carotid blowout syndrome for patients receiving head and neck salvage boron neutron capture therapy (BNCT) EN Tien-Li Lan Division of Radiotherapy, Department of Oncology, Taipei Veterans General Hospital Feng-Chi Chang Department of Radiology, Taipei Veterans General Hospital Chun-Wei Wang Division of Radiotherapy, Department of Oncology, Taiwan University Hospital Kazuyo Igawa Neutron Therapy Research Center, Okayama University Szu-Hsien Wu Division of Plastic and Reconstructive Surgery, Taipei Veterans General Hospital Wen-Liang Lo Division of Oral and Maxillofacial Surgery, Department of Stomatology, Taipei Veterans General Hospital Yi-Wei Chen Division of Radiotherapy, Department of Oncology, Taipei Veterans General Hospital Background/purpose The incidence rate of oral and pharyngeal cancers in Taiwan has increased gradually over the past few decades. The standard treatment strategy for oral and pharyngeal cancers includes surgery or radiotherapy, with concurrent chemotherapy in certain types of tumors. Unfortunately, in-field recurrence is sometimes inexorable. Furthermore, re-irradiation of the recurrence site may cause severe complications due to the tolerance of normal tissue to radiation therapy. One fatal complication is carotid blowout syndrome (CBS). Boron neutron capture therapy (BNCT) is a new modality of radiation therapy, which is also mentioned as targeted radiotherapy. It is a feasible treatment that has the potential to spare normal tissue from being damaged by irradiation while simultaneously treating the primary tumor. In this presentation, we will share our experience with BNCT in treating recurrent head and neck cancers, as well as the prevention and management of CBS. Materials and methods We evaluated 4 patients with head and neck cancers treated by BNCT in Taiwan. All patients had undergone surgery previously and had received postoperative concurrent chemoradiotherapy. Results The 4 patients in this study were diagnosed with head and neck malignancies. The median follow-up period after the first course of BNCT was 15.1 months. After BNCT, 2 patients developed impending CBS, and 1 of them died. The remaining 3 patients survived until the last date of follow-up. Conclusion Pre-BNCT carotid artery evaluation through computed tomography angiography and early intervention if necessary is crucial when treating patients with recurrent head and neck cancers by BNCT. No potential conflict of interest relevant to this article was reported.