Image Based Evaluation of Tumor Targeting and Efficacy of Gene Therapy

描述(申请人提供)：尽管基因疗法和细胞疗法很有前途，但它们缺乏专门定位表达或细胞贩运的方法。报告基因既可以定位又可以量化表达。在临床前肿瘤模型中，我们证明了生长抑素受体2a(SSTR2)基因嵌合体的转移可以在体内进行量化。当针对癌症进行治疗时，SSTR2激发的生长抑制信号可能是有利的，但对于糖尿病等疾病或评估感兴趣的关联基因时，可能不是所希望的，例如癌症。我们建议创建一个可想象的、信号缺陷的SSTR2。这位记者将对一些疾病状态和应用具有广泛的适用性。大多数基因转移技术使用构成启动子，在各种组织中驱动高水平的表达。当引入有毒基因时，启动子可能被用于靶向肿瘤，而不是正常组织。端粒酶活性在几乎所有的肿瘤中都存在，但在几乎所有的正常组织中都不存在或很少。这种分布是由人端粒酶逆转录酶(HTERT)启动子模拟的。包括hTERT在内的组织特异性启动子的一个缺点是它们驱动转录的能力相对较弱。我们建议建立一个扩增的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的影响或对可以驱动hTERT表达的旁观者细胞的影响，我们建议创建具有信号缺陷报告基因的这种结构。我们使用FDA批准的放射性药物奥曲肽，对人生长抑素受体基因111嵌合体在肿瘤中的体内表达进行了量化。临床上，非侵入性方法，包括用于评估肿瘤大小变化的解剖成像，是评估疗效的理想方法。结合功能成像和解剖成像，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。具体目的1.验证信号缺陷的生长抑素受体2型(SSTR2)可以作为基因转移报告的假设。2.验证一种假设，即扩增的hTERT启动子与报告基因连锁，例如信号缺陷的SSTR2驱动肿瘤中的表达，并且该表达可以在体内成像。3.验证这样一种假设，即与治疗基因连锁的信号缺陷SSTR2可用于监测连锁治疗基因的表达和疗效。该项目可能会为监测癌症治疗提供新的工具，并增加可通过功能和解剖成像技术以非侵入性方式解决的疾病范围。公共卫生相关性：该项目可能为监测癌症治疗提供新的工具；同时，增加可通过功能和解剖成像技术以非侵入性方式解决的疾病范围。

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.