Development of Novel Immunotherapy of Cancer: NKp44-based Chimeric Antigen Receptors and Methods for Ex Vivo NK cell Expansion

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K10015
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Pediatrics
• Research Institution: Niigata University
• Principal Investigator: Imai Chihaya 新潟大学, 医歯学系, 准教授 (90419284)
• Co-Investigator(Renkei-kenkyūsha): IMAMURA MASARU 新潟大学, 医歯学総合病院, 講師 (80464006) ; Takachi Takayuki 新潟大学, 医歯学総合病院, 特任助教 (70444164)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: キメラ抗原受容体 / NK細胞 / CAR-T細胞 / NK細胞受容体 / NKp44 / がん免疫療法

Outline of Final Research Achievements

We have developed novel chimeric antigen receptors (CAR) as well as a novel method for ex vivo natural killer cell (NK) expansion. We tried to optimize methodology to propagate NK cells with a feeder cell line, K562-mb15-41BBL, by changing several parameters, such as culture medium, E/T ratio, timing of irradiation, and additional drugs. We constructed a variety of CARs that utilize immunoglobulin domain of NKp44 receptor as an antigen-binding portion, which were tested for their surface expression and resulting functional diversities. Following completion of construction of 1st generation CAR, we also optimized the structure of 2nd generation 4-1BB-based NKp44-CAR. Primary human T cells or NK cells, transduced with NKp44-based CAR, are able to express the CAR protein on the cell surface, produce cytokines, and exert strong cytotoxic effects against a wide variety of leukemia cells and solid tumor cells.

Free Research Field

小児血液学

Academic Significance and Societal Importance of the Research Achievements

近年、難治性の急性リンパ性白血病およびリンパ腫に対するキメラ抗原受容体遺伝子導入T細胞（CAR-T）療法の目覚ましい成果が報告されている。CAR-T療法は急性骨髄性白血病や種々の固形腫瘍への応用が期待されているが、適切な標的抗原の選択が難しく、いまだに成功例はほとんどない。本研究では、体外増幅NK細胞療法から発展し、T細胞にNK細胞様の選択性を付与できるCAR遺伝子を作成した。B細胞性腫瘍以外の悪性腫瘍に対するCAR-T療法の開発においては、標的抗原ロスや免疫抑制的がん微小環境などの克服すべき問題点が多いが、NKp44-CARはその幅広い対象疾患から有力な候補となり得る。