Antigen Specific Immunotherapy with Transduced HSC

描述(申请人提供)：本项目的目标是研究基因修饰的骨髓移植(BMT)诱导强大的抗肿瘤免疫的效用。肿瘤免疫治疗的一个主要焦点是开发策略，通过树突状细胞(DC)有效地提呈肿瘤抗原来诱导T细胞反应。目前的疫苗接种策略在体内有效负载DC的能力有限。体外产生的树突状细胞可以被有效负载，但重新注射后，很少有树突状细胞运输到次级淋巴器官，而次级淋巴器官是向T细胞呈递抗原的关键部位。为了提高DC提呈抗原的效率和持久性，我们用编码模型肿瘤抗原的慢病毒载体转导造血干细胞(HSC)，然后将修饰的细胞移植到HSC。我们的结果表明，DC在淋巴器官中高水平表达了转基因。使用表达抗原的HSC的骨髓移植和激活DC的全身药物与成熟的供者淋巴细胞输注相结合，导致抗原特异性T细胞的戏剧性扩张和激活。这种三联疗法为侵袭性已建立的小鼠淋巴瘤提供了有效的抗原特异性免疫疗法。在这一应用中，我们建议研究肿瘤免疫反应的机制和动力学，通过可调节的载体选择性表达肿瘤抗原，并优化治疗策略。具体地说，我们将：(1)以HA为肿瘤抗原模型，检测接受Ag转导的骨髓干细胞(HSCs)的小鼠的T细胞免疫反应；(2)研究HSC转导/移植后DC的体内激活和T细胞启动的分子组合，并开发DC特异性的和药理上可调控的载体，以增强对抗原的免疫应答；(3)确定肿瘤抗原在骨髓中的表达对清髓性和非清髓性异基因骨髓移植的疗效；以及(4)确定Ag转导的BM移植是否将有效地对抗实体瘤。

DESCRIPTION (provided by applicant): The goal of this project is to investigate the utility of bone marrow transplant (BMT) with gene modified BM to induce potent anti-tumor immunity. A major focus of cancer immunotherapy is to develop strategies to induce T cell responses through efficient presentation of tumor antigens by dendritic cells (DCs). Current vaccination strategies are limited in their ability to efficiently load DCs in vivo. Ex vivo generated DCs can be efficiently loaded, but after re-injection, few DCs traffic to secondary lymphoid organs, which are the critical sites for antigen presentation to T cells. To enhance the efficiency and durability of antigen presentation by DCs, we transduced hematopoietic stem cells (HSC) with a lentiviral vector encoding a model tumor antigen, then transplanted the modified cells. Our results showed high-level expression of a transgene by DCs in lymphoid organs. The combination of bone marrow-transplant using antigen expressing HSC and systemic agents that activate DCs along with mature donor lymphocyte infusions resulted in dramatic expansion and activation of antigen specific T cells. This tripartite therapy provided potent antigen specific immunotherapy of an aggressive established murine lymphoma. In this application, we are proposing to investigate the mechanism and kinetics of the immune response to the tumor, selective expression of the tumor Ag by regulatable vectors, and optimization of the treatment strategy. Specifically, we will: (1) examine the T cell immune responses in mice receiving Ag-transduced bone marrow stem/progenitor cells (HSCs), using HA as a model tumor Ag; (2) investigate combinations of molecules for in vivo activation of DCs and T cell priming subsequent to HSC transduction/transplantation, and develop DC specific and pharmacologically regulatable vectors to enhance immune responsiveness to antigen; (3) determine the efficacy of tumor Ag expression in the BM for myeloablative and nonmyeloablative allogeneic BMT; and (4) determine whether transplantation of Ag transduced BM will be effective against solid tumors.