Image Based Evaluation of Tumor Targeting and Efficacy of Gene Therapy

描述（由申请人提供）：虽然基因治疗和细胞治疗有很大的前景，但它们缺乏特异性定位表达或细胞运输的方法。报告基因可以定位和量化表达。在临床前肿瘤模型中，我们证明了生长抑素受体2a型（SSTR2）基因嵌合体的转移可以在体内量化。由SSTR2激发的生长抑制信号在针对癌症进行治疗时可能是有利的，但对于糖尿病等疾病或评估相关基因（如癌症）时可能不是理想的。我们建议创建一个可想象的信号缺陷SSTR2。该报告将广泛适用于许多疾病状态和应用。大多数基因转移技术使用组成启动子来驱动各种组织中的高水平表达。当引入有毒基因时，启动子可能用于靶向肿瘤，而不是正常组织。端粒酶在几乎所有肿瘤中都有活性，但在几乎所有正常组织中不存在或活性极低。这种分布被人类端粒酶逆转录酶（hTERT）启动子模仿。组织特异性启动子（包括hTERT）的一个缺点是它们驱动转录的能力相对较弱。我们建议创建一个扩增的hTERT启动子报告系统用于肿瘤特异性成像。为了限制启动子泄漏对正常细胞或可以驱动hTERT表达的旁观者细胞的影响，我们建议使用信号缺陷报告基因构建这种结构。我们已经使用FDA批准的放射性药物奥曲肽在肿瘤中量化了人生长抑素受体基因111嵌合体的体内表达。临床上，非侵入性方法，包括解剖成像来评估肿瘤大小的变化，是评估疗效的理想方法。结合功能和解剖成像，我们将测试报告系统是否可以用于监测相关治疗的表达以及预测疗效。1.具体目标验证信号缺陷型生长抑素受体2 （SSTR2）可以作为基因转移的报告者的假设。2. 验证与报告基因（如信号缺陷的SSTR2）相关的扩增hTERT启动子驱动肿瘤中的表达的假设，并且该表达可以在体内成像。3. 验证与治疗性基因相关的信号缺陷SSTR2可用于监测相关治疗性基因的表达和疗效的假设。这个项目可能会为监测癌症治疗提供新的工具；此外，增加疾病的范围，可以解决的功能和解剖成像技术，非侵入性。公共卫生相关性：该项目可能为监测癌症治疗提供新工具；此外，增加疾病的范围，可以解决的功能和解剖成像技术，非侵入性。

DESCRIPTION (provided by applicant): Although gene therapy and cellular therapies have great promise, they suffer from a lack of methods for specifically locating expression or cell trafficking. Reporter genes can both locate and quantify expression. In a pre-clinical tumor model, we demonstrated that transfer of a somatostatin receptor type 2a (SSTR2) gene chimera can be quantified in vivo. The growth inhibitory signaling incited by the SSTR2 may be advantageous when targeting cancer for therapy, but may not be desirable for disorders such as diabetes or when evaluating a linked gene of interest, such as for cancer. We propose to create an imagable, signaling deficient SSTR2. This reporter will have broad applicability for a number of disease states and applications. Most gene transfer techniques use constitutive promoters that drive high levels of expression in a variety of tissues. When introducing a toxic gene, promoters may be used to target tumors, and not normal tissues. Telomerase activity is found in nearly all tumors, but is absent or minimal in almost all normal tissues. This distribution is mimicked by the human telomerase reverse transcriptase (hTERT) promoter. A disadvantage of tissue specific promoters, including hTERT, is that their ability to drive transcription is relatively weak. We propose to create an amplified hTERT promoter-reporter system for tumor specific imaging. To limit effects on normal cells due to promoter leakiness or on bystander cells that can drive hTERT expression, we propose to create such constructs with signaling deficient reporters. We have quantified in vivo expression of a human somatostatin receptor gene 111 chimera in tumors using the FDA approved radiopharmaceutical in octreotide. Clinically, non-invasive methods, including anatomic imaging to assess change in tumor size, are desirable to assess efficacy. Combining functional and anatomic imaging, we will test whether the reporter system can be used to monitor expression of a linked therapeutic as well as to predict efficacy. Specific aims 1. Test the hypothesis that a signaling deficient somatostatin receptor type 2 (SSTR2) can function as a reporter of gene transfer. 2. Test the hypothesis that an amplified hTERT promoter linked to a reporter, such as a signaling deficient SSTR2 drives expression in tumors and the expression can be imaged in vivo. 3. Test the hypothesis that a signaling deficient SSTR2 linked to a therapeutic gene can be used to monitor expression and efficacy of a linked therapeutic gene. This project potentially will provide new tools for monitoring cancer treatment; as well as, increase the range of diseases that can be addressed by functional and anatomic imaging techniques, non-invasively. PUBLIC HEALTH RELEVANCE: This project potentially will provide new tools for monitoring cancer treatment; as well as, increase the range of diseases that can be addressed by functional and anatomic imaging techniques, non-invasively.