Investigation of Novel Host Tumor Immunostimulatory Effects Induced by Boron Neutron Capture Therapy

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K17231
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 52040:Radiological sciences-related
• Research Institution: Kyoto University
• Principal Investigator: Watanabe Tsubasa 京都大学, 複合原子力科学研究所, 特定准教授 (30804348)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 中性子捕捉療法

Outline of Final Research Achievements

Boron neutron capture therapy (BNCT) is a cancer treatment that utilizes the fission of boron atoms into alpha and lithium nuclei when they capture a neutron. The purpose of this study was to investigate the anti-tumor immune response after BNCT. Using a subcutaneous tumor model of mice with malignant melanoma cells, B16, we simultaneously administered BNCT and aCD8 antibody, and found a clear decrease in the anti-tumor effect, indicating that the anti-tumor immune response contributes to the anti-tumor effect of BNCT as well as X-rays and γ-rays. The combination group of BNCT plus aPD1 showed better anti-tumor effect than BNCT alone in terms of change in tumor curve and survival rate. The results of the study showed that the combination of BNCT and aPD1 improved the antitumor effect compared to BNCT alone in terms of tumor curve change and survival rate.

Free Research Field

放射線生物学

Academic Significance and Societal Importance of the Research Achievements

実験動物を用いたモデルにおいて、BNCTにおいてもX線・γ線などの通常放射線治療として用いられる線種と同様に、抗腫瘍効果に対する宿主の免疫応答も重要であることが判明した。そこで、同モデルを用いてBNCTと抗PD-1抗体の同時併用による癌治療効果を検討し、BNCTと抗PD-1抗体の同時併用による上乗せ効果を認めた。これは既に一部癌腫に対して保険適応にもなっているBNCTの後治療として抗PD-1抗体が有用である可能性を示唆するものであり、既存の治療とのシナジーを求めて臨床でも併用する根拠の１つとなると考える。