Novel therapeutic strategy for ovarian cancer targeting immune tolerance-inducing molecules, PD-L1 and IDO, using genome editing technique

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K11293
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Obstetrics and gynecology
• Research Institution: Wakayama Medical University
• Principal Investigator: INO KAZUHIKO 和歌山県立医科大学, 医学部, 教授 (60303640)
• Co-Investigator(Kenkyū-buntansha): 近藤 稔和 和歌山県立医科大学, 医学部, 教授 (70251923) ; 馬淵 泰士 和歌山県立医科大学, 医学部, 講師 (80382357)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 免疫寛容 / ゲノム編集 / 卵巣癌 / PD-L1 / IDO / 免疫療法 / マウスモデル

Outline of Final Research Achievements

This study focused on two immune tolerance-inducing molecules, Programmed cell death ligand 1 (PD-L1) and Indoleamine 2,3-dioxygenase (IDO), and their targeting therapy in ovarian cancer. PD-L1 was genetically disrupted in the murine ovarian cancer cell ID8 using CRISPR/Cas9-mediated genome editing. PD-L1 knockout (KO) and control ovarian cancer cells were intraperitoneally inoculated into mice. Survival time was significantly longer in the PD-L1-KO ID8-inoculated group, and tumor weight was significantly lower in the PD-L1-KO ID8 group. Intratumoral CD8+ T cells and NK cells were significantly increased in the PD-L1-KO ID8 group. The intratumoral mRNA expression of IFN-γ, TNF-α, IL-2, IL-12a, CXCL9/10 was significantly stronger in the PD-L1-KO ID8 groups. These results indicated that CRISPR/Cas9-mediated PD-L1 disruption promotes anti-tumor immunity, thereby suppressing ovarian cancer progression. Further studies are needed to evaluate the effects of targeting therapy for IDO.

Free Research Field

婦人科腫瘍学

Academic Significance and Societal Importance of the Research Achievements

卵巣癌の有する免疫回避機構を克服するため、宿主T細胞側のPD-1でなく腫瘍細胞側に発現するIDOやPD-L1の標的治療の有用性を詳細に検討した研究は乏しい。本研究においては、これらの免疫寛容誘導分子を従来のsh－RNAによるノックダウンではなく、CRISPR/Cas9によるゲノム編集により完全にノックアウトさせる方法を試みた点は学術的意義がある。本研究が卵巣癌における腫瘍微小環境内免疫寛容システムのさらなる解明を促進し、将来、アデノ随伴ウイルス等を用いてin vivoで癌自身の免疫寛容分子を特異的にブロックする遺伝子治療開発への基盤構築に貢献することが期待できる。