Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90095, USA.
Neurotherapeutics. 2012 Oct;9(4):827-43. doi: 10.1007/s13311-012-0144-7.
Immune-mediated gene therapy using adenovirus expressing Flt3 ligand and thymidine kinase followed by ganciclovir administration (Flt3/TK) effectively elicits tumor regression in preclinical glioma models. Herein, we assessed new strategies to optimize Flt3L/TK therapeutic efficacy in a refractory RG2 orthotopic glioblastoma model. Specifically, we aimed to optimize the therapeutic efficacy of Flt3L/TK treatment in the RG2 model by overexpressing the following genes within the brain tumor microenvironment: 1) a TK mutant with enhanced cytotoxicity (SR39 mutant TK), 2) Flt3L-IgG fusion protein that has a longer half-life, 3) CD40L to stimulate DC maturation, 4) T helper cell type 1 polarizing dendritic cell cytokines interleukin-12 or C-X-C motif ligand 10 chemokine (CXCL)-10, 5) C-C motif ligand 2 chemokine (CCL2) or C-C motif ligand 3 chemokine (CCL3) to enhance dendritic cell recruitment into the tumor microenvironment, 6) T helper cell type 1 cytokines interferon-γ or interleukin-2 to enhance effector T-cell functions, and 7) IκBα or p65RHD (nuclear factor kappa-B [NF-κB] inhibitors) to suppress the function of Foxp3+ Tregs and enhanced effector T-cell functions. Anti-tumor immunity and tumor specific effector T-cell functions were assessed by cytotoxic T lymphocyte assay and intracellular IFN-γ staining. Our data showed that overexpression of interferon-γ or interleukin-2, or inhibition of the nuclear factor kappa-B within the tumor microenvironment, enhanced cytotoxic T lymphocyte-mediated immune responses and successfully extended the median survival of rats bearing intracranial RG2 when combined with Flt3L/TK. These findings indicate that enhancement of T-cell functions constitutes a critical therapeutic target to overcome immune evasion and enhance therapeutic efficacy for brain cancer. In addition, our study provides novel targets to be used in combination with immune-therapeutic strategies for glioblastoma, which are currently being tested in the clinic.
利用表达 Flt3 配体和胸苷激酶的腺病毒进行免疫介导的基因治疗，随后给予更昔洛韦（Flt3/TK），可有效诱导临床前神经胶质瘤模型中的肿瘤消退。在此，我们评估了优化 Flt3L/TK 治疗在难治性 RG2 原位神经胶质瘤模型中的疗效的新策略。具体而言，我们旨在通过在脑肿瘤微环境中过表达以下基因来优化 Flt3L/TK 治疗的疗效：1）具有增强细胞毒性的 TK 突变体（SR39 突变型 TK）；2）具有更长半衰期的 Flt3L-IgG 融合蛋白；3）CD40L 以刺激 DC 成熟；4）辅助性 T 细胞 1 型极化树突状细胞细胞因子白细胞介素 12 或 C-X-C 基序趋化因子 10（CXCL-10）；5）C-C 基序趋化因子 2 趋化因子（CCL2）或 C-C 基序趋化因子 3 趋化因子（CCL3）以增强树突状细胞向肿瘤微环境中的募集；6）辅助性 T 细胞 1 型细胞因子干扰素-γ或白细胞介素 2 以增强效应 T 细胞的功能；7）IκBα或 p65RHD（核因子 kappa-B [NF-κB] 抑制剂）以抑制 Foxp3+Tregs 的功能并增强效应 T 细胞的功能。通过细胞毒性 T 淋巴细胞测定和细胞内 IFN-γ染色评估抗肿瘤免疫和肿瘤特异性效应 T 细胞功能。我们的数据表明，在肿瘤微环境中过表达干扰素-γ或白细胞介素 2，或抑制核因子 kappa-B，可增强细胞毒性 T 淋巴细胞介导的免疫反应，并在与 Flt3L/TK 联合使用时成功延长了颅内 RG2 荷瘤大鼠的中位生存期。这些发现表明，增强 T 细胞功能是克服免疫逃逸和增强脑癌治疗效果的关键治疗靶点。此外，我们的研究为胶质母细胞瘤的免疫治疗策略提供了新的靶点，目前正在临床中进行测试。
