Department of Oncology, University of Oxford, Oxford, UK.
Target Discovery Institute, University of Oxford Nuffield Department of Medicine, Oxford, UK.
J Immunother Cancer. 2024 May 9;12(5):e008460. doi: 10.1136/jitc-2023-008460.
Glioblastoma (GBM) almost invariably becomes resistant towards conventional treatment of radiotherapy and temozolomide (TMZ) chemotherapy, partly due to subpopulations of intrinsically resistant glioma stem-like cells (GSC). The oncolytic herpes simplex virus-1 G207 is a promising approach for GBM virotherapy although its efficacy in patients with GBM is often limited. Natural killer group 2 member D ligands (NKG2DLs) are minimally expressed by healthy cells but are upregulated by the DNA damage response (DDR) and in malignant cells with chronic DDR signaling, resulting in innate immune activation.
We have designed a bispecific T-cell engager (BiTE) capable of cross-linking CD3 on T cells with NKG2DL-expressing GBM cells. We then engineered the G207 virus to express the NKG2D BiTE and secrete it from infected cells. The efficacy of the free BiTE and BiTE delivered by G207 was evaluated in combination with conventional therapies in GBM cells and against patient-derived GSCs in the context of T-cell activation and target cell viability.
NKG2D BiTE-mediated cross-linking of GBM cells and T cells causes antigen-independent T-cell activation, pro-inflammatory cytokine release, and tumor cell death, thereby combining direct viral oncolysis with BiTE-mediated cytotoxicity. Surface NKG2DL expression was further elevated on GBM cells following pretreatment with sublethal doses of TMZ and radiation to induce the DDR, increasing sensitivity towards G207-NKG2D BiTE and achieving synergistic cytotoxicity. We also demonstrate a novel strategy for targeting GSCs that are non-permissive to G207 infection but remain sensitive to NKG2D BiTE.
We propose a potential model for targeting GSCs in heterogeneous tumors, whereby differentiated GBM cells infected with G207-NKG2D BiTE produce NKG2D BiTE locally, directing T-cell cytotoxicity towards the GSC subpopulations in the tumor microenvironment.
胶质母细胞瘤（GBM）几乎不可避免地对放射治疗和替莫唑胺（TMZ）化疗的常规治疗产生耐药性，部分原因是存在内在耐药性的胶质瘤干细胞样细胞（GSC）亚群。溶瘤单纯疱疹病毒 1 G207 是 GBM 病毒治疗的一种很有前途的方法，尽管其在 GBM 患者中的疗效往往受到限制。自然杀伤细胞组 2 成员 D 配体（NKG2DL）在健康细胞中表达很少，但在 DNA 损伤反应（DDR）和具有慢性 DDR 信号的恶性细胞中上调，导致先天免疫激活。
我们设计了一种能够交联 T 细胞上的 CD3 和表达 NKG2DL 的 GBM 细胞的双特异性 T 细胞衔接器（BiTE）。然后，我们对 G207 病毒进行了工程改造，使其表达 NKG2D BiTE 并从感染的细胞中分泌出来。在 T 细胞激活和靶细胞存活的情况下，评估了游离 BiTE 和 G207 递送的 BiTE 与常规疗法联合在 GBM 细胞中和针对患者来源的 GSCs 的疗效。
NKG2D BiTE 介导的 GBM 细胞和 T 细胞交联导致抗原非依赖性 T 细胞激活、促炎细胞因子释放和肿瘤细胞死亡，从而将直接病毒溶瘤作用与 BiTE 介导的细胞毒性结合起来。用亚致死剂量的 TMZ 和辐射预处理后，GBM 细胞表面 NKG2DL 的表达进一步升高，以诱导 DDR，增加对 G207-NKG2D BiTE 的敏感性并实现协同细胞毒性。我们还证明了一种针对 GSCs 的新策略，该策略对 G207 感染不允许，但对 NKG2D BiTE 敏感。
我们提出了一种针对异质性肿瘤中 GSCs 的潜在模型，其中感染 G207-NKG2D BiTE 的分化 GBM 细胞局部产生 NKG2D BiTE，将 T 细胞细胞毒性导向肿瘤微环境中的 GSC 亚群。
