Grp94 targeted therapy for pancreatic ductal adenocarcinoma

描述(申请人提供)：目前，胰腺导管腺癌(PDAC)仍是最致命的癌症之一，目前还没有有效的治疗方法。为了回应临床开发创新治疗策略的需要，这 该提案将测试一种新的组合免疫治疗策略的治疗效果，该策略不仅针对分化的PDAC细胞，还针对PDAC癌症起始细胞(CICs)。这些被确认为ALDHbright细胞的细胞必须被根除才能“治愈”一种恶性疾病，因为根据癌症干细胞理论，这些细胞是疾病复发和转移的罪魁祸首。作为靶点的肿瘤抗原是热休克蛋白90(HSP90)家族中的一员--94 kDa的葡萄糖调节蛋白(Grp94)。Grp94调节与细胞增殖、存活和迁移相关的几个信号通路的激活。为了针对Grp94，我们将利用我们最近鉴定的人mAbW9的独特特异性。MAb W9识别细胞外Grp94表位，该表位在包括人PDAC细胞和PDAC CIC在内的恶性细胞上选择性表达，但在正常组织中不表达。MAb W9能显著抑制人PDAC细胞(包括PDAC CICs)的体外增殖，并诱导其凋亡。单抗W9与环多巴胺和5-氟尿嘧啶结合后，抗增殖和促凋亡活性增强。环多巴胺和5-氟尿嘧啶均抑制Sonic hedgehog信号通路，该信号通路在PDAC中异常激活，特别是在基质和PDAC CICs中。为了评估这些体外数据在体内的相关性，这项建议的具体目的将检验以下假设：i)W9单抗定义的Grp94表位在原发PDAC肿瘤中的表达与其组织病理学特征和预后不良有关；ii)单抗W9与环多巴胺和5-FU联合使用，在根除免疫缺陷小鼠原位移植到PDAC细胞系MIA Paca-2上的PDAC肿瘤方面比单独使用或两种药物联合使用更有效；Iii)用PDAC细胞系MIA Paca-2获得的结果将具有潜在的临床意义，因为它们是在免疫缺陷小鼠身上复制的，这些小鼠原位移植的PDAC肿瘤是从患者身上切除的。从体外和动物模型系统中概述的研究中获得的信息将为在PDAC患者中实施单抗W9的I期临床试验提供有用的背景。这项试验的实施将得益于C.Ferrone博士在马萨诸塞州波士顿的马萨诸塞州总医院通过PDAC与她的患者接触，她新获得的进行临床试验的技能，以及mAbW9的完全人性化。

DESCRIPTION (provided by applicant): At present, no effective therapy is available for the treatment of pancreatic ductal adenocarcinoma (PDAC), which continues to be one of the most lethal cancers. In response to the clinical need to develop innovative therapeutic strategies, this proposal will test the therapeutic efficacy of a novel combinatorial immunotherapeutic strategy, which targets not only differentiated PDAC cells, but also PDAC cancer initiating cells (CICs). These cells, identified as ALDHbright cells, have to be eradicated in order to "cure" a malignant disease, because, according to the cancer stem cell theory, these cells are responsible for disease recurrence and metastases. The tumor antigen selected as a target is the glucose-regulated protein of 94 kDa (Grp94), a member of the heat shock protein 90 (HSP90) family. Grp94 regulates the activation of several signaling pathways which are associated with cell proliferation, survival and migration. To target Grp94, we will take advantage of the unique specificity of the human mAb W9, which we have recently characterized. mAb W9 recognizes an extracellular Grp94 epitope that is selectively expressed on malignant cells, including human PDAC cells and PDAC CICs, but not in normal tissues. mAb W9 markedly inhibits the in vitro proliferation of human PDAC cells, including PDAC CICs, and induces their apoptosis. The anti-proliferative and pro-apoptotic activity of mAb W9 is enhanced by combining it with cyclopamine and 5-FU. Both cyclopamine and 5-FU inhibit the sonic hedgehog signaling pathway, which is aberrantly activated in PDAC, particularly in the stroma and PDAC CICs. To assess the in vivo relevance of these in vitro data, the specific aims of this proposal will test the following hypotheses: i) The expression of the mAb W9 defined Grp94 epitope in primary PDAC tumors is associated with their histopathological characteristics and with poor prognosis; ii) mAb W9, in combination with cyclopamine and 5-FU, is more effective than individual agents, or a combination of two agents, in eradicating PDAC tumors in immunodeficient mice orthotopically grafted with the PDAC cell line MIA PaCa-2; iii) The results obtained with the PDAC cell line MIA PaCa-2 will have potential clinical significance, as they are reproduced in immunodeficient mice orthotopically grafted with PDAC tumors surgically removed from patients. The information derived from the outlined studies in vitro and in animal model systems will provide a useful background to implement a Phase I clinical trial with the mAb W9 in patients with PDAC. The implementation of this trial will be facilitated by Dr. C. Ferrone's access to her patients wit PDAC at Massachusetts General Hospital, Boston, MA, her newly acquired skills in conducting clinical trials, and by the fully human nature of the mAb W9.