Androgen receptor targeted vaccines for prostate cancer

描述(申请人提供)：前列腺癌是一个重要的世界性健康问题，需要新的治疗方法。我们研究的目标是开发有效的主动免疫疗法，即肿瘤疫苗，作为前列腺癌的治疗方法。在这项应用中，我们建议评估一种新的免疫治疗靶抗原，雄激素受体(AR LBD)的配体结合域，雄激素受体(AR LBD)是一种与前列腺癌生长和进展有关的生物学分子。我们先前已经证明，前列腺癌患者存在AR LBD特异性的体液和细胞免疫反应，AR LBD特异性的细胞溶解CD8+T细胞可以以HLA-A2 MHC I类限制性方式溶解人类前列腺癌细胞。此外，我们已经证明了编码AR LBD的DNA疫苗可以在人类白细胞抗原A2转基因小鼠中诱导出表位特异的CD8+T细胞。此外，我们先前已经证明，HSP72的表达增加可以增加MHC-I类分子的表达和抗原提呈。在目前的方案中，我们假设编码AR LBD的DNA疫苗可以激发多肽特异性的抗肿瘤免疫反应，并且对DNA疫苗的修饰允许增加抗原呈递可以增强抗肿瘤免疫反应。这将在人类白细胞抗原A2转基因小鼠和表达人类白细胞抗原A2的前列腺癌转基因小鼠模型中进行评估。对于所有这些研究，我们将只关注蛋白质的配体结合结构域(LBD)，并将使用对特定HLA-A2表位的响应作为免疫有效性的读数，这些标记可以类似地用于人类临床试验。此外，我们将评估编码HSP72的DNA疫苗和/或DNA疫苗内的蛋白酶体靶向信号是否能够增强体内的抗原提呈和抗原特异性细胞溶解T细胞(CTL)反应，以及抗肿瘤免疫反应。最后，基于这些结果，我们将进行一项I期临床试验，以评估编码AR LBD的DNA疫苗在去势抵抗、非转移性前列腺癌患者中的安全性和免疫学效果，无论是否进行修改以促进抗原递呈。该提案的具体目的将是：1)确定编码AR LBD的DNA疫苗是否能在HLA-A2转基因小鼠中诱导抗原特异性CD8+T细胞和抗前列腺癌反应；2)在DNA疫苗的背景下，确定HSP72或蛋白酶体靶向信号与模型抗原的共表达是否能增强表达HLA-A2转基因小鼠的抗原特异性CD8+T细胞效应免疫反应和抗肿瘤反应；以及3)确定编码AR LBD的DNA疫苗在去势耐药非转移性前列腺癌患者中的安全性和免疫学效果，无论是否有HSP72和/或蛋白酶体靶向信号的共表达。 公共卫生相关性：前列腺癌是一个重大的世界性健康问题，也是美国男性癌症相关死亡的第二大原因。人们迫切需要前列腺癌的新疗法。这项研究的目标是开发有效的抗肿瘤DNA疫苗来治疗癌症，特别是前列腺癌。因此，这项提议与国家癌症研究所的使命直接相关。这项建议将表征和评估前列腺癌的一种新的疫苗靶标抗原，即雄激素受体的配体结合域。50多年来，雄激素受体一直是转移性前列腺癌治疗的关键药理学靶点，但以前还没有对其作为免疫靶标抗原的评估。此外，我们的项目寻求通过在免疫时增加靶抗原的呈递来确定提高DNA疫苗效力的方法。因此，这些研究的结果应该广泛适用于其他基因疫苗。最后，这项提案将在前列腺癌复发高危患者的人类临床试验中评估这些发现。

DESCRIPTION (provided by applicant): Prostate cancer is a significant worldwide health problem for which new treatments are needed. The goal of our research is to develop effective active immunotherapies, tumor vaccines, as a treatment for prostate cancer. In this application we propose to evaluate a novel immunotherapy target antigen, the ligand-binding domain of the androgen receptor (AR LBD), a biologically relevant molecule to prostate cancer growth and progression. We have previously demonstrated that patients with prostate cancer have existing humoral and cellular immune responses specific for the AR LBD, and that cytolytic CD8+ T cells specific for the AR LBD can lyse human prostate cancer cells in an HLA-A2 MHC class I-restricted fashion. In addition, we have demonstrated that a DNA vaccine encoding the AR LBD can elicit epitope-specific CD8+ T cells in an HLA-A2 transgenic mouse. Moreover, we have previously shown that increased expression of Hsp72 can increase MHC class I expression and antigen presentation. In the current proposal we hypothesize that a DNA vaccine encoding the AR LBD can elicit peptide- specific anti-tumor immune responses, and that modifications to a DNA vaccine permitting increased antigen presentation can augment anti-tumor immune responses. This will be evaluated in HLA-A2 transgenic mice, and in an HLA-A2-expressing transgenic mouse model of prostate cancer. For all of these studies we will focus on the ligand-binding domain (LBD) of the protein only, and will use the generation of responses to specific HLA-A2 epitopes as a read-out for immunological efficacy, markers which can be similarly used in a human clinical trial. In addition, we will evaluate whether DNA vaccines encoding hsp72 and/or a proteasome-targeting signal within a DNA vaccine can augment antigen presentation and antigen-specific cytolytic T- cell (CTL) responses, and anti-tumor immune responses in vivo. Finally, based on these results, we will conduct a phase I clinical trial to evaluate the safety and immunological efficacy of a DNA vaccine encoding the AR LBD, with or without modifications to facilitate antigen presentation, in patients with castrate-resistant, nonmetastatic prostate cancer. The specific aims of the proposal will be: 1) to determine whether a DNA vaccine encoding the AR LBD can elicit antigen-specific CD8+ T-cells and anti-prostate tumor responses in HLA-A2 transgenic mice; 2) to determine whether co-expression of Hsp72 or a proteasome-targeting signal with a model antigen in the context of a DNA vaccine can augment antigen-specific CD8+ T-cell effector immune responses and anti-tumor responses in HLA-A2-expressing transgenic mice; and 3) to determine the safety and immunological efficacy of a DNA vaccine encoding the AR LBD, with or without co-expression of Hsp72 and/or a proteasome-targeting signal, in patients with castrate-resistant nonmetastatic prostate cancer. PUBLIC HEALTH RELEVANCE: Prostate cancer is a significant worldwide health problem, and the second leading cause of cancer-related death in men in the United States. New treatments for prostate cancer are urgently needed. The goal of this research is to develop effective anti-tumor DNA vaccines as a treatment for cancer, and prostate cancer in particular. Thus, this proposal is directly relevant to the mission of the National Cancer Institute. This proposal will characterize and evaluate a new vaccine target antigen in prostate cancer, the ligand binding domain of the androgen receptor. The androgen receptor has been the key pharmacological target for metastatic prostate cancer treatment for over 50 years, but there has been no previous evaluation of this as an immunological target antigen. In addition, our project seeks to identify means of increasing the efficacy of DNA vaccines by increasing presentation of the target antigen at the time of immunization. As such the results from these studies should be widely applicable to other genetic vaccines. Finally, this proposal will evaluate these findings in a human clinical trial in patients at high risk for prostate cancer metastatic recurrence.