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

描述（由申请人提供）：癌症免疫疗法为许多癌症的治疗提供了有希望的前景。然而，肿瘤已经发展出通过形成免疫抑制细胞来抑制免疫的策略，例如调节性T细胞和MDSC，其可以反过来抑制免疫效应细胞并向肿瘤微环境中分泌更多的免疫抑制细胞因子。因此，显然需要一种强有力的疗法来引发抗肿瘤免疫反应以克服任何免疫抑制因素。颗粒状天然病毒样颗粒（VLP）已被证明能诱导强烈的免疫应答，因此是克服肿瘤免疫抑制的一种有前途的工具。该提案研究了通过新的蛋白质转移方法将糖基-磷脂酰肌醇（GPI）锚定的肿瘤相关抗原（GPI-TAAs）沿着GPI锚定的免疫刺激分子（GPI-ISM）（例如细胞因子、共刺激分子和粘附分子）掺入到脂质包膜VLP（例如流感VLP）的表面上。VLP表面上TAA的缔合将允许免疫应答针对也在肿瘤细胞上缔合的这些TAA，而在VLP表面上沿着TAA添加ISM将允许增加VLP的摄取和呈递以及增强抗原呈递细胞的活化。此外，在VLP的表面上包含GPI-细胞因子允许在免疫位点处缓慢释放储库，从而增加疫苗的功效。这种蛋白质转移方法需要使用GPI锚定的蛋白质与包膜VLP在37 ° C下孵育较短的孵育时间。孵育后，GPI蛋白自发掺入VLP的脂质双层。这种蛋白质转移方法使我们能够克服当遗传修饰VLP以表达蛋白质时诱导的任何细胞病理学效应。因此，该方法还允许将许多GPI-蛋白同时掺入到相同的VLP上，并且可以容易地控制GPI-蛋白的表达水平。在产生所得嵌合VLP后，我们打算研究这些蛋白质转移的VLP在具有已建立肿瘤的小鼠中引发肿瘤消退的功效，并通过分析细胞和体液免疫应答来研究导致消退的免疫相关性。我们将使用转染以表达TAA、HER-2的4 T07鼠乳腺癌模型进行这些研究。因此，我们建议通过蛋白质转移将GPI-HER-2和GPI-ISM掺入到包膜VLP的表面上，以增强具有已建立肿瘤的小鼠的抗肿瘤免疫应答和肿瘤消退。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，以治疗现有肿瘤或预防人类转移性生长。

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.