Therapuetic Immune Targeting of EphA2 Expressed by Melanoma & Its Tumor-Associate

我们最近发现超过90%的黑色素瘤过度表达受体酪氨酸激酶 (RTK)EphA 2，EphA 2过表达水平与转移表型相关， 临床预后使用配体肝配蛋白A1-Ig交联肿瘤细胞表达的EphA 2分子 融合蛋白或激活抗EphA 2抗体导致RTK磷酸化，随后受体 内化、c-Cbl依赖性泛素化和蛋白酶体依赖性降解。因此，在这方面， 激动剂处理的肿瘤细胞获得了更良性的表型，根据我们的初步数据， 有条件地上调它们在MHC I类复合物中呈递的EphA 2衍生表位的表达。 使用EphA 2特异性CTL细胞系和克隆，我们已经在初步数据中显示，用这些细胞系和克隆进行治疗， EphA 2配体激动剂导致抗EphA 2 CD 8 + T细胞对肿瘤细胞的识别和杀伤的改善 在Hu-SCID模型中的体外和体内。我们最近还观察到， 蛋白酪氨酸磷酸酶（PTP）或HSP 90的功能也用于增加EPhA 2前体的表达。 加工，理论上使EphA 2肽可进入MHC I类生物合成途径。我们 假设EphA 2配体激动剂和PTP/HSP 90抑制剂可以协同地促进EphA 2的表达， 增强CTL对肿瘤细胞的识别。因此，我们假设， 免疫疗法由以下组成：1）基于EphA 2的疫苗，其被设计为引发特异性CTL，和2）免疫疗法， 通过局部区域施用的EphA 2降解和蛋白酶体加工的条件活化 EphA 2配体激动剂或PTP/HSP 90抑制剂将导致改善的抗黑素瘤功效。我们的具体 目的是”评价促进EphA 2蛋白酶体加工的“激动剂”致敏EphA 2蛋白酶体的能力“。 黑色素瘤细胞体外抗EphA 2 CD 8 + T细胞识别（AIM 1）;检验以下假设： 靶向EphA 2的条件性蛋白酶体加工的组合免疫疗法是安全的， 在小鼠体内模型（AIM 2）中，比单一模式疗法更有效; 涉及DC 1/EphA 2肽免疫和条件免疫的组合疗法的I期临床试验 在晚期HLA-A2+患者中增强EphA 2衍生表位的肿瘤呈递 黑色素瘤（AIM 3）。

We have recently determined that more than 90% of melanomas overexpress the receptor tyrosine kinase (RTK) EphA2, with the EphA2 level of overexpression associated with metastic phenotype and an adverse clinical prognosis. Cross-linking of tumor cell-expressed EphA2 molecules using either ligand Ephrin A1-lg fusion proteins or activating anti-EphA2 antibodies results in RTK phosphorylation, followed by receptor internalization, c-Cbl-dependent ubiquitination and proteasome-dependent degradation. As a consequence, agonist-treated tumor cells acquire a more benign phenotype, and based on our preliminary data, they conditionally up-regulate their expression of EphA2-derived epitopes presented in MHC class I complexes. Using EphA2-specific CTL lines and clones, wehave shown in preliminary data that treatment with these EphA2 ligand agonists results in improved recognition and killing of tumor cells by anti-EphA2 CD8+ T cells in vitro and in vivo in Hu-SCID models. We have also recently observed that pharmacologic inhibition of protein tyrosine phosphatases (PTP) or HSP90 function also serves to increase EPhA2 preteasomal processing, theoretically making EphA2 peptides accessible to the MHC class I biosynthetic pathway. We hypothesize that EphA2 ligand agonists and PTP/HSP90 inhibitors may act synergistically in promoting enhanced tumor cell recognition by CTLs. As a consequence, we hypothesize that combinational immunotherapies consisting of 1) EphA2-based vaccines designed to elicit specific CTLs and 2) the conditional activation of EphA2 degradation and proteasomal processing via locoregional administration of EphA2 ligand agonists or PTP/HSP90 inhibitors will result in improved ani-melanoma efficacy. Our Specific Aims are to" Evaluate the ability of "agonists" that promote EphA2 proteasomal processing to sensitize melanoma cells to anti-EphA2 CD8+ T cell recognition in vitro (AIM 1); Test the hypothesis that combinational immunotherapies targeting the conditional proteasomal processing of EphA2 are safe and more effective than single modality therapies in mouse models in vivo (AIM 2); and Design and perform a phase I clinical trial of a combinational therapy involving DC1/EphA2 peptide immunization and conditional augmentation of tumor presentation of EphA2-derived epitopes in HLA-A2+ patients with advanced-stage melanoma (AIM 3).