Development of an Ad5-CEA/Brachyury Vector Approach for Cancer Treatment

描述（由申请人提供）：随着与肿瘤发展相关的新生物标志物的发现，这些肿瘤相关抗原（TAA）中的许多被用于设计用于诱导抗肿瘤定向细胞毒性免疫应答的免疫疗法。越来越清楚的是，这些TAA中的任何一种都不足以作为开发免疫治疗剂的单一实体。因此，我们的努力集中在开发针对TAA的多靶向免疫方法上。当前项目的总体目标是使用多靶向方法扩展我们治疗转移性结直肠癌（mCRC）的免疫方法。美国国家癌症研究所的Jeffery Schlom和James Gully博士同意与我们合作实现这一目标。我们使用Ad 5 [E1-，E2 b-]-CEA（6D）（ETBX-011）免疫抑制剂作为单一药物，在mCRC患者中实现了安全性、剂量反应和总生存期增加。我们认为，添加抗癌干细胞（CSC）方法可以提高疗效，特别是针对肿瘤转移。因此，我们将Brachyury添加为TAA CSC靶标。Brachyury代表了一种相对较新但有吸引力的免疫治疗靶点。它是转录因子的T-box家族的成员，在早期发育过程中发挥关键作用，主要在正常中胚层的形成和分化中发挥关键作用，其特征在于高度保守的DNA结合结构域，称为T结构域。最近，上皮间质转化（EMT）已被认为是原发性肿瘤进展为转移状态的关键步骤，其中短尾畸形起着至关重要的作用。肿瘤EMT已被证明与CSC样特征的获得相关，包括CSC样特征的获得和维持，对常规治疗，化疗和放疗以及一些小分子靶向治疗的抗性。Brachyury在人癌细胞中的过表达诱导EMT特征性变化，包括间充质标志物的上调、上皮标志物的下调以及细胞迁移和侵袭的增加。重要的是，Brachyury是免疫原性的，并且体外扩增的Brachyury特异性CD 8 + T细胞可以裂解表达Brachyury的肿瘤细胞。这些特征使其成为更有吸引力的TAA之一，可广泛用于免疫目的，尤其是用于mCRC。Brachyury被整合到我们的重组Ad 5 [E1-，E2 b-]平台中，用于治疗mCRC的多重免疫治疗方法。我们相信，这个平台将实现多重免疫，这将在功能上增强对该靶点的免疫反应，并可能预防转移。我们将把Brachyury整合到我们的重组Ad 5 [E1-，E2 b-]平台中，以产生一种新的、更有效的针对mCRC的免疫抑制剂，该免疫抑制剂将靶向原代和mCRC干细胞。我们相信这两个TAA靶标作为单一递送免疫抑制剂，将通过靶向CSC增强我们的Ad 5 [E1-，E2 b-]- CEA（6D）方法的临床应答，并将导致mCRC患者的总生存期增加。

DESCRIPTION (provided by applicant): With the discovery of new biomarkers associated with tumor development, many of these tumor-associated antigens (TAA) are being utilized in immunotherapeutic modalities designed to induce anti-tumor directed cytotoxic immune responses. It is increasingly clear that not any one of these TAA is sufficient, as a single entity to develop an immunotherapeutic treatment agent. Consequently, our efforts are being focused on developing multi-targeted immunotherapeutic approach against TAA. The overall goal of the current project is to expand our immunotherapeutic approach for the treatment of metastatic colorectal cancer (mCRC) using a multiple targeted approach. Drs. Jeffery Schlom and James Gully at the National Cancer Institute have agreed to collaborate with us to reach this goal. We have achieved safety, dose response, and an increased overall survival in mCRC patients using our Ad5 [E1-, E2b-]-CEA(6D) (ETBX-011) immunotherapeutic as a single agent. We believe that adding an anti-cancer stem cell (CSC) approach can lead to increased efficacy particularly against tumor metastases. Thus, we have added Brachyury as a TAA CSC target. Brachyury represents a relatively new but attractive target for immunotherapy. It is a member of the T-box family of transcription factors that play key roles during early development, mostly in the formation and differentiation of normal mesoderm and is characterized by a highly conserved DNA-binding domain designated as T-domain. Recently, epithelial-mesenchymal transition (EMT) has been recognized as a key step during the progression of primary tumors into a metastatic state in which Brachyury plays a crucial role. Tumor EMT has been demonstrated to be associated with the acquisition of CSC-like features that includes acquisition and maintenance of CSC-like characteristics, resistance to conventional therapeutics, chemotherapy and radiation, and to some small-molecule targeted therapies. Over-expression of Brachyury in human carcinoma cells induces changes characteristic of EMT, including up-regulation of mesenchymal markers, down-regulation of epithelial markers, and an increase in cell migration and invasion. Importantly, Brachyury is immunogenic and Brachyury-specific CD8+ T cells expanded in vitro can lyse Brachyury expressing tumor cells. These features make it one of the more attractive TAA that can be utilized broadly for immunotherapeutic purposes but especially for mCRC. Brachyury is incorporated into our recombinant Ad5 [E1-, E2b-] platform for use in the multiple immunotherapy approach to treat mCRC. We believe that this platform will enable multiple immunizations that will functionally boost the immune response to this target and may prevent metastases. We will incorporate Brachyury into our recombinant Ad5 [E1-, E2b-] platform to produce a new and more potent immunotherapeutic for mCRC that will target primary and mCRC stem cells. We believe these two TAA targets as a single delivery immunotherapeutic agent, will enhance the clinical responses of our Ad5 [E1-, E2b-]- CEA(6D) approach by targeting CSC and will result in an increased overall survival of patients with mCRC.