Novel target antigens for ovarian cancer immunotherapy

描述(申请人提供)：三分之二的卵巢癌患者在确诊时已经是晚期疾病，卵巢癌是妇科恶性肿瘤中死亡率最高的。基于诱导肿瘤特异性细胞毒性T淋巴细胞(CTL)反应的免疫治疗对这些患者来说可能是一个有吸引力的选择。我们已经鉴定了一系列新的卵巢肿瘤抗原，包括肿瘤相关差异表达基因14(TADG-14)产物TADG-15、肝素、角质层糜胰酶(SCCE)，它们都是丝氨酸蛋白酶，以及基质金属蛋白酶Pump-L。这些抗原在卵巢癌中高表达，但在正常卵巢或大多数正常成人组织中不表达，提示它们可能是树突状细胞(DC)免疫治疗的良好靶抗原。这项提议将检验这样一种假设，即抗原或多肽负载的DC可用于诱导卵巢癌患者的特异性T淋巴细胞反应，以及肿瘤抗原特异性CTL将溶解卵巢肿瘤细胞。我们已经证明，多肽负载的DC刺激人类白细胞抗原I类限制性CDS CTL，即溶解抗原表达的靶点，包括与人类白细胞抗原匹配的卵巢肿瘤细胞。第一个特定目标将确定进一步的CTL表位，并确定DC刺激的卵巢癌患者多肽特异性CD8 CTL是否能溶解卵巢肿瘤细胞。我们还将测试新的人类白细胞抗原I类单链三聚体是否能诱导多肽特异性的CD8CTL反应。在第二个特定目标中，我们将构建包含已定义的CTL表位和具有退化的人类白细胞抗原II类结合潜力的候选辅助T细胞表位的多肽。负载多表位多肽的DC将被测试其诱导抗原特异性CD8 CTL反应和CD4辅助T细胞反应的能力。这一策略的基本原理是，抗原特异性的CD4T细胞在体内为诱导和维持有效的CD8T细胞反应提供必要的帮助。我们还将测试从最近发现的内含子序列翻译而来的多肽的免疫原性，这些内含子序列表达于变异的肝素和TADG-14中。第三个特异性目标将确定负载全长重组肿瘤抗原的DC或转染线性DNA构建体的DC是否能诱导卵巢癌患者的CD8、CTL和CD4T细胞应答。这项建议旨在开发治疗性DC疫苗预防卵巢癌进展的临床试验方案。

DESCRIPTION (provided by applicant): Two-thirds of ovarian cancer patients have advanced disease at the time of diagnosis, and ovarian cancer has the highest mortality rate among gynecological malignancies. Immunotherapy based on induction of tumor-specific cytotoxic T lymphocyte (CTL) responses may represent an attractive option for these patients. We have identified a series of novel ovarian tumor antigens, including the tumor-associated differentially expressed gene 14 (TADG-14) product, TADG-15, hepsin, stratum corneum chymotryptic enzyme (SCCE), all of which are serine proteases, and the matrix metalloprotease, pump-l. These antigens are highly expressed in ovarian cancer but not in normal ovaries or the majority of other normal adult tissues, suggesting that they may be excellent target antigens for dendritic cell (DC) immunotherapy. This proposal will test the hypothesis that antigen or peptide-loaded DC can be used to induce specific T lymphocyte responses from patients with ovarian cancer, and that tumor antigen-specific CTL will lyse ovarian tumor cells. We have shown that peptide-loaded DC stimulate HLA class I-restricted CDS+ CTL that lyse antigen-expressing targets, including HLA-matched ovarian tumor cells. The 1st Specific Aim will identify further CTL epitopes and determine whether DC-stimulated peptide-specific CD8+ CTL from ovarian cancer patients lyse ovarian tumor cells. We will also test whether DC transfected with novel HLA class I single chain trimers induce peptide-specific CD8+ CTL responses. In the 2nd Specific Aim, we will construct peptides that encompass defined CTL epitopes and candidate CD4+ helper T cell epitopes with degenerate HLA class II binding potential. DC loaded with multi-epitope peptides will be tested for their ability to induce antigen-specific CD8+ CTL responses and CD4+ helper T cell responses. The rationale for this strategy is that antigen-specific CD4+ T cells provide essential help for the induction and maintenance of effective CD8+ T cell responses in vivo. We will also test the immunogenicity of peptides translated from recently discovered intron sequences expressed in variant hepsin and TADG-14. The 3rd Specific Aim will determine whether DC loaded with full-length recombinant tumor antigen or transfected with linear DNA constructs induce CD8+ CTL and CD4+ T cell responses from ovarian cancer patients. This proposal is targeted at the development of clinical trial protocols for therapeutic DC vaccination for prevention of progression of ovarian cancer.