Tumor rejection antigens induced via epitope spreading

描述（由申请人提供）：人类肿瘤具有免疫原性，已鉴定出许多肿瘤抗原。肿瘤免疫学家现在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是[1]对肿瘤的潜在生物学至关重要的抗原，[2]是由T辅助细胞、溶细胞性T细胞和抗体组成的高强度多方面免疫应答的靶标，[3]免疫应答赋予治疗益处的抗原。我们实验室以前的研究表明，IV期乳腺癌患者可以成功地用HER-2/neu（HER 2）肽疫苗免疫，导致表位扩散和改善生存。分子内和分子间表位扩散都是免疫的结果。在自身免疫性疾病中，表位扩散与侵袭性组织特异性破坏相关。表位扩散可以解释为什么我们的患者生存率提高。鉴定在IV期乳腺癌患者群体中发生表位扩散的抗原可能有助于开发靶向和特异性破坏肿瘤组织的癌症疫苗策略。我们的假设是，这些抗原可能是肿瘤排斥抗原。该提案的具体目的是：（1）使用源自用基于HER 2肽的疫苗免疫的乳腺癌患者的血清鉴定潜在的“肿瘤排斥”抗原，所述乳腺癌患者在主动免疫后表现出表位扩散和延长的存活，和（2）确定通过血清学筛选鉴定的抗原是否可以被源自乳腺癌患者的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”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IgG抗体应答是高滴度的，这意味着被CD 4 + T辅助细胞识别。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由CD 4 + T辅助细胞库（2）和潜在的CTL识别的。我们将使用来自IV期乳腺癌患者的免疫后血清，这些患者在用HER 2肽疫苗免疫后具有改善的存活率和表位扩散，以鉴定新的免疫原性蛋白。免疫诱导的新抗原将通过“减去”疫苗前血清识别的抗原来鉴定。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。我们的目标是开发与肿瘤破坏和生存益处相关的基于免疫的策略（例如疫苗）。

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.