Tumor antigen-decorated virus-like particles as a therapeutic cancer vaccine

描述(申请人提供)：癌症免疫疗法为许多癌症的治疗提供了一个很有前途的前景。然而，肿瘤通过形成免疫抑制细胞(如调节性T细胞和MDSCs)来抑制免疫，进而抑制免疫效应细胞并将更多的免疫抑制细胞因子分泌到肿瘤微环境中。因此，显然需要一种强有力的治疗方法来诱导抗肿瘤免疫反应，以克服任何免疫抑制因素。颗粒性质的病毒样颗粒(VLP)已被证明能诱导强烈的免疫反应，因此被认为是克服肿瘤免疫抑制的一种有前途的工具。本研究通过一种新的蛋白质转移方法，将糖基磷脂酰肌醇锚定的肿瘤相关抗原(GPI-TAAs)和GPI锚定的免疫刺激分子(GPI-ISM)，如细胞因子、共刺激分子和黏附分子，整合到脂质包裹的VLP(如流感VLP)的表面。VLP表面的TAA的结合将允许免疫反应针对这些也与肿瘤细胞相关的TAA，而VLP表面的ISM与TAA一起增加VLP的摄取和提呈，以及增强抗原提呈细胞的激活。此外，VLP表面的GPI细胞因子允许在免疫部位建立一个缓慢释放的储存库，从而提高疫苗的效力。这种蛋白质转移方法需要使用GPI锚定的蛋白质与被包裹的VLP在37℃下孵育较短的时间。在孵育时，GPI-蛋白自发地结合到VLP的脂双层上。这种蛋白质转移方法使我们能够克服通过基因修饰VLP来表达蛋白质时所引起的任何细胞病理效应。因此，这种方法还允许将许多GPI-蛋白同时整合到同一VLP上，并且GPI-蛋白的表达水平可以很容易地控制。在产生嵌合VLP后，我们打算研究这些蛋白转移VLP在已建立肿瘤的小鼠中诱导肿瘤消退的有效性，并通过分析细胞和体液免疫反应来研究导致消退的免疫相关因素。我们将使用4T07小鼠乳腺癌模型来表达TAA，HER-2，用于这些研究。因此，我们建议通过蛋白质转移将GPI-HER-2和GPI-ISMS整合到包膜VLP的表面，以增强已建立肿瘤的小鼠的抗肿瘤免疫反应和肿瘤消退。从这些研究中获得的知识将为开发基于VLP的有效治疗性癌症疫苗奠定基础，以治疗现有的肿瘤或防止人类转移生长。

DESCRIPTION (provided by applicant): Cancer immunotherapy provides a promising outlook for the treatment of many cancers. However, tumors have developed strategies to suppress immunity through the formation of immunosuppressive cells, such as regulatory T cells and MDSCs, which can in turn suppress immune effector cells and secrete more immunosuppressive cytokines into the tumor microenvironment. Therefore, the need for a strong therapy to elicit an anti-tumor immune response to overcome any immunosuppressive factors is evident. The particulate natured virus-like particles (VLPs) have been shown to induce a strong immune response, and thus present as a promising tool to overcome immunosuppression by tumors. This proposal studies the incorporation of glycosyl-phosphatidylinositol (GPI)-anchored tumor associated antigens (GPI-TAAs) along with GPI-anchored immunostimulatory molecules (GPI-ISMs), such as cytokines, costimulatory molecules, and adhesion molecules, onto the surface of lipid enveloped VLPs, such as influenza VLPs, by a novel protein transfer approach. The association of TAAs on the surface of VLPs will allow the immune response to be directed against these TAAs that are also associated on tumor cells, whereas the addition of ISMs on the VLP surface along with the TAAs will allow for increased uptake and presentation of the VLPs as well as enhanced activation of antigen presenting cells. Furthermore, inclusion of GPI-cytokines on the surface of VLPs allows for a slow release depot at the immunization site, thus increasing the efficacy of the vaccine. This protein transfer approach requires the use of GPI-anchored proteins to be incubated with enveloped VLPs at 37oC for a short incubation time. Upon incubation, spontaneous incorporation of the GPI-proteins onto the lipid bilayer of the VLPs occurs. This protein transfer method allows us to overcome any cytopathological effects induced when genetically modifying VLPs to express proteins. Thus, this approach also allows for the incorporation of many GPI-proteins onto the same VLP simultaneously and the expression levels of the GPI-proteins can be easily controlled. After production of the resulting chimeric VLPs, we intend to study the efficacy of these protein transferred-VLPs in eliciting tumor regression in mice with established tumors and study the immune correlates that lead to regression by analyzing cellular and humoral immune responses. We will be using a 4T07 murine breast cancer model transfected to express the TAA, HER-2, for these studies. Therefore, we propose to incorporate GPI-HER-2 and GPI-ISMs onto the surface of enveloped VLPs by protein transfer to enhance antitumor immune responses and tumor regression in mice with established tumors. The knowledge obtained from these studies will form a foundation to develop VLP-based efficacious therapeutic cancer vaccines to treat existing tumors or lead to the prevention of metastatic growth in humans.