Tumor rejection antigens induced via epitope spreading

描述(申请人提供)：人类肿瘤具有免疫原性，已鉴定出许多肿瘤抗原。肿瘤免疫学家目前面临的一个问题是确定哪些抗原与肿瘤组织的破坏有关，即肿瘤排斥抗原。理想的肿瘤排斥抗原应该是那些[1]对肿瘤的基本生物学至关重要的抗原，[2]是由T辅助细胞、细胞溶解T细胞和抗体组成的多方面免疫反应的目标，以及[3]那些免疫反应带来治疗益处的抗原。我们实验室以前的研究表明，HER-2/neu(HER2)多肽疫苗可以成功地免疫IV期乳腺癌患者，从而扩大表位，提高生存率。免疫导致分子内和分子间表位扩散。在自身免疫性疾病中，表位扩散与侵袭性组织特异性破坏有关。表位的传播可能解释了为什么我们的患者提高了存活率。在这群IV期乳腺癌患者中识别那些发生表位扩散的抗原，可能会被证明对开发癌症疫苗策略有帮助，以靶向并特异性地摧毁肿瘤组织。我们的假设是，这些抗原可能是肿瘤排斥抗原。这项建议的具体目的是：(1)使用以HER2多肽为基础的疫苗免疫的乳腺癌患者的血清，识别潜在的“肿瘤排斥”抗原，这些患者在主动免疫后表现出表位扩散和延长生存期，以及(2)确定通过血清学筛选鉴定的抗原是否能被乳腺癌患者的T细胞识别。 我们将使用重组cDNA表达文库的血清学分析技术或“SEREX”技术来筛选肿瘤特异性抗原，这些抗原是免疫后表位扩散的结果。以这种方式鉴定的许多肿瘤特异性抗体反应都是高滴度的，暗示着CD4+T辅助细胞的识别。因此，假设使用抗体免疫作为筛选工具发现的抗原可以被认为是被CD4+T辅助细胞库(2)识别的，并有可能被CTL识别。我们将使用来自IV期乳腺癌患者的免疫后血清，这些患者在接种HER2多肽疫苗后，既改善了生存率，又扩大了表位分布，以识别新的免疫原性蛋白。免疫诱导的新抗原将通过对疫苗前血清识别的抗原进行减法识别。随后的研究将确定这些通过血清学筛选鉴定的新抗原是否可以作为T细胞靶点。我们的目标是开发基于免疫的策略(例如疫苗)，这些策略将与肿瘤破坏和生存益处相关。

DESCRIPTION (provided by applicant): Human tumors are immunogenic and many tumor antigens have been identified. A problem now facing tumor immunologists is to determine what antigens are relevant to the destruction of tumor tissue, i.e. tumor rejection antigens. Ideal tumor rejection antigens would be ones that [1] are essential to the underlying biology of the tumor, [2] are the targets of a multifaceted immune response of high magnitude consisting of T helper cells, cytolytic T cells, and antibodies, and, [3] those to which an immune response confers therapeutic benefit. Previous studies from our laboratory have shown that stage IV breast cancer patients can be successfully immunized with HER-2/neu (HER2) peptide vaccines resulting in epitope spreading and improved survival. Both intramolecular and intermolecular epitope spreading occurred as a result of immunization. In autoimmune disease, epitope spreading is associated with aggressive tissue specific destruction. Epitope spreading may explain why our patients had improved survival. Identifying those antigens to which epitope spreading occurred in this population of stage IV breast cancer patients may prove useful in developing cancer vaccine strategies to target and specifically destroy tumor tissue. Our hypothesis is that these antigens may be tumor rejection antigens. The specific aims of this proposal are to: (1) identify potential "tumor rejection" antigens using sera derived from breast cancer patients immunized with a HER2 peptide-based vaccine who demonstrated epitope spreading and prolonged survival after active immunization, and, (2) determine whether antigens, identified through serologic screening, can be recognized by T cells derived from breast cancer patients. We will use the technique of serological analysis of recombinant cDNA expression libraries or "SEREX" to screen for tumor-specific antigens that were the result of epitope spreading following immunization. Many of the tumor specific IgG antibody responses identified in this fashion are high titer implying recognition by CD4+ T helper cells. Thus, it is assumed that antigens discovered using antibody immunity as a screening tool can be considered to be recognized by the CD4+ T helper cell repertoire (2) and, potentially, CTL. We will use post-immunization sera derived from Stage IV breast cancer patients that had both improved survival and epitope spreading following immunization with a HER2 peptide vaccine to identify novel immunogenic proteins. New antigens induced by immunization will be identified by "subtraction" of antigens recognized by the pre-vaccine serum. Subsequent studies will determine whether these new antigens, identified via serologic screening, can serve as T cell targets. Our goal is to develop immune-based strategies (e.g. vaccines) that would be associated with tumor destruction and survival benefit.