Tailoring AAV Vectors for Glioma Immunotherapy

描述(申请人提供)：腺相关病毒(AAV)是目前正在开发的一种领先的基因递送系统。AAV血清型是高度神经营养的，在中枢神经系统(CNS)单次注射后能够高水平的长期基因表达。AAV在胶质瘤(GL)模型中的基因转移显示，不同血清型之间的转导效率存在很大差异，尽管有报道称AAV在体外对小胶质细胞(MG)的转导有限，但这些细胞在动物中的转导效果很差。这项建议的主要目的是开发选择性转导GL细胞和侵袭这些肿瘤的MG的AAV载体，并将这些AAV血清型和天然AAV血清型应用于GL免疫治疗。除了以GL细胞本身为靶点外，大量MG渗入GL提示了另一个潜在的开发GL基因治疗的靶点。MG细胞是中枢神经系统的主要免疫效应细胞，具有体外杀伤肿瘤的能力。支持体内类似作用的证据来自于研究发现，丰富的、激活的MG是人类和实验性GL的一致特征。然而，MG和其他GL浸润性淋巴细胞(如细胞毒性T细胞)的功能在免疫抑制的GL微环境中受到抑制。因此，我们将检验假设：(1)具有GL和肿瘤浸润性MG选择性转导特征的AAV载体可以被选择用于使用具有复制能力的AAV组合衣壳蛋白文库，其特征是随机病毒表面环；(2)在衣壳表面显示主要T细胞表位并同时表达全长GL抗原的AAV载体可以用作GL免疫治疗的“Prime-Boost”疫苗载体；以及(3)系统和中央输送表达MG和/或调节性T细胞的免疫修饰物的AAV载体可以诱导对GL的有效免疫应答。在全面推进AAV载体平台的同时，这些载体的开发和鉴定将为了解GL的免疫应答提供有价值的见解。此外，选择性靶向MG的AAV载体的开发将在广泛的中枢神经系统疾病中具有广泛的适用性。 公共卫生相关性：胶质瘤是成人最常见的脑瘤。尽管通过手术、放疗和化疗进行积极治疗，但患者的生存预后很差。在了解胶质瘤患者的抗肿瘤免疫方面取得了重大进展。这项建议评估腺相关病毒基因治疗提高免疫系统对胶质瘤肿瘤细胞发动更有效攻击的能力的潜力。

DESCRIPTION (provided by applicant): Adeno-associated virus (AAV) is a leading gene delivery system currently under development. AAV serotypes are highly neurotrophic and capable of high levels of long term gene expression following a single injection in the central nervous system (CNS). AAV gene transfer in glioma (GL) models has revealed that transduction efficiencies are highly variable between serotypes, and despite reports of limited AAV transduction of microglia (MG) in vitro, transduction of these cells in animals is poor. The major goal of this proposal is to develop AAV vectors characterized by selective transduction of GL cells as well as the MG that infiltrate these tumors, and to apply these and native AAV serotypes in GL immunotherapy. In addition to targeting the GL cells themselves, the high number of MG that infiltrate GL suggests another potentially exploitable target for developing GL gene therapy. MG cells are the primary immune effectors of the CNS with demonstrated tumor killing capacity in vitro. Evidence to support a similar role in vivo comes from the finding that abundant, activated MG are a consistent feature of human and experimental GL. Yet the function of MG and other GL infiltrating lymphocytes (such as cytotoxic T cells) are inhibited within the immunosuppressive GL microenvironment. Therefore, we will test the hypotheses that (1) AAV vectors with GL and tumor-infiltrating MG selective transduction profiles can be selected for using replication-competent AAV combinatorial capsid protein libraries characterized by randomized virion surface loops; (2) AAV vectors that display dominant T-cell epitopes on the capsid surface, while simultaneously expressing the full length GL antigen, can be employed as "prime-boost" vaccine carriers for GL immunotherapy; and (3) systemic and central delivery of AAV vectors that express immune modifiers of MG and/or regulatory T-cells can elicit potent immune responses to GL. While advancing the AAV vector platform generally, the development and characterization of these vectors will provide valuable insight into the immune response to GL. Furthermore, the development of AAV vectors that selectively target MG would have broad applicability in a wide range of CNS disorders. Public Health Relevance: Glioma is the most common brain tumor in adults. Despite aggressive treatment with surgery, radiotherapy, and chemotherapy prognosis for survival is poor. Significant advances have been made in understanding anti-tumor immunity in the glioma patient This proposal evaluates the potential of adeno-associated virus gene therapy to boost the immune system's ability to mount a more effective attack on glioma tumor cells.