Cancer and Stroma-Targeted Immunotherapy with a Gentically Modified DC Vaccine

描述（由申请人提供）：该项目的目的是开发一种有效的实体瘤树突状细胞（DC）疫苗。虽然 DC 疫苗可以诱导有效的外周 T 细胞免疫，但其抗肿瘤作用有限。这很可能是由于肿瘤内存在免疫抑制细胞，例如调节性 T 细胞 (Treg) 以及肿瘤运动基质。虽然针对 Tregs 或癌症相关成纤维细胞（CAF，肿瘤基质的主要成分）的疫苗策略已在动物模型中产生完全反应，但由于效应 T 细胞功能被侵蚀和/或颠覆，肿瘤不可避免地会复发。我们现在假设，通过不仅靶向肿瘤和 Tregs，还靶向 CAF，T 细胞效应器功能将保留更长时间，局部“肿瘤促进天堂”将被破坏，从而导致肿瘤持续缓解。我们进一步假设，肿瘤中产生的有效免疫刺激环境将导致表位扩散，因为肿瘤基质内新激活的抗原呈递细胞“交叉呈递”垂死的肿瘤细胞。为了检验这些假设，我们将利用我们的初步研究，其中我们已经证明沉默 DC 中的负调节因子 A20 可以克服 Treg 介导的免疫抑制，从而在 B16 模型中产生有效的抗肿瘤反应。此外，我们还表明，A20 沉默的 DC 疫苗可以诱导针对 CAF 细胞表面表达的成纤维细胞激活蛋白（FAP）的有效免疫反应。使用 B16 模型，我们将在目标 1 中评估共表达 A20-shRNA、FAP 和 TRP2 (DC-shA20-FAP-TRP2) 的 DC 疫苗是否能逆转抑制性肿瘤微环境并促进 T 细胞浸润到肿瘤中，并在目标 2 中确定我们的疫苗诱导旁观者 T 细胞反应（表位扩散）的效力，从而消除肿瘤抗原丢失变异。在目标 3 中，我们将评估我们的疫苗在自发鼠 Hgf-Cdk4R24c 黑色素瘤模型中的有效性和安全性。这项拟议的研究具有高度创新性，因为它将首次测试转基因树突状细胞诱导针对癌细胞及其支持基质的 T 细胞反应的能力，同时在单一疫苗配方中克服 Treg 介导的免疫抑制。如果这种临床前方法成功并且临床验证合理，我们就有资源来制备符合适当的良好生产规范安全标准的载体和细胞成分，并将为此类研究寻求单独的资金。 公共健康相关性：由于恶性肿瘤主动抑制免疫系统，人体对癌症的免疫防御常常会失败。免疫系统不仅受到癌细胞的抑制，而且还受到周围非癌细胞的抑制。我们建议开发一种攻击癌细胞和免疫抑制周围细胞的疫苗。疫苗的效果将在动物模型中进行评估。

DESCRIPTION (provided by applicant): The intent of this project is to develop an effective dendritic cell (DC) vaccine for solid tumors. While DC vaccines can induce potent peripheral T-cell immunity, their antitumor effects have been limited. This is most likely due to the presence of immunosuppressive cells within the tumor, such as regulatory T cells (Tregs), as well as tumor sporting stroma. While vaccine strategies targeting Tregs or cancer associated fibroblasts (CAFs, the major component of tumor stroma) have produced complete responses in animal models, tumors inevitably recur, as effector T-cell functions are eroded and/or subverted. We now hypothesize that by targeting not only the tumor and Tregs, but also CAFs, T-cell effector function will be retained for longer and the local 'tumor promoting heaven' will be destroyed resulting in sustained tumor remissions. We further hypothesize that the potent immunostimulatory environment created in the tumor will result in epitope spreading as newly activated antigen presenting cells within the tumor stroma 'cross-present' dying tumor cells. To test these hypotheses we will take advantage of our preliminary studies in which we have demonstrated that silencing the negative regulator A20 in DC can overcome Treg mediated immune suppression resulting in potent antitumor responses in the B16 model. In addition, we have shown that an A20-silenced DC vaccine can induce potent immune responses against fibroblast activating protein (FAP) expressed on the cell surface of CAFs. Using the B16 model, we will evaluate in Aim 1 if a DC vaccine coexpressing A20-shRNA, FAP and TRP2 (DC-shA20-FAP-TRP2) reverses the suppressive tumor microenvironment and facilitates T-cell infiltration into tumors, and determine in Aim 2 the potency of our vaccine to induce bystander T-cell responses (epitope spreading), leading to elimination of tumor antigen loss variants. In Aim 3 we will then evaluate the efficacy and safety of our vaccine in a spontaneous murine Hgf-Cdk4R24c melanoma model. The proposed study is highly innovative since it will test for the first time the ability of genetically modified DCs to induce T-cell responses against cancer cells and their supporting stroma, while concomitantly overcoming Treg-mediated immunosuppression in a single vaccine formulation. If this pre-clinical approach is successful and clinical validation appears justified, we have the resources to prepare vector and cellular components that conform to the appropriate Good Manufacturing Practices safety standards, and will seek separate funding for such a study. PUBLIC HEALTH RELEVANCE: The body's immune defenses against cancers often fail because malignancies actively inhibit the immune system. The immune system is not only suppressed by the cancer cells but also by the surrounding none cancerous cells. We propose to develop a vaccine that attacks cancer cells and the immunosuppressive surrounding cells. The effect of the vaccine will be evaluated in animal models.