A Nanotechnology Platform for Suicide Gene Therapy of Recurring Ovarian Cancer

描述(申请人提供)：卵巢癌是美国所有妇科恶性肿瘤中死亡率最高的，总的5年生存率为30-40%。虽然大多数肿瘤最初对手术和化疗与顺铂等以铂为基础的药物相结合的标准治疗有效，但大多数接受治疗的患者获得多药耐药性，并因复发而屈服于他们的疾病。肿瘤起始细胞(CICs)也被称为肿瘤干细胞，在肿瘤复发和转移扩散中发挥重要作用。因此，为了抑制复发，提高患者的生存率，设计一种在早期治疗中根除分化的卵巢癌细胞和CICs的治疗策略至关重要。基于这一前提，本研究的主要目标是开发一种靶向治疗系统，既能有效地杀死分化的癌细胞，又能有效地杀死CIC，并证明不仅能根除 对原发肿瘤也有抑制复发的作用。实体瘤具有复杂的病理生理机制，毛细血管渗漏程度、细胞外蛋白、肿瘤异质性和肿瘤细胞密度等因素显著限制了治疗分子的分布和疗效。作为一名 结果，分化的癌细胞和/或CICs亚群可能在治疗中存活。为了克服这些障碍并实现这一目标，我们开发了一种新型的高效靶向屏蔽纳米技术平台(载体)，它利用被动、主动和转录靶向机制，在对正常组织影响最小的情况下，在肿瘤部位实现高抗癌活性。我们的活体动物成像和肿瘤回归研究表明，所开发的系统在肿瘤中被动积聚，被肿瘤细胞主动拾取，有效地在肿瘤中特异地转染和表达报告基因，而不是在其他组织中，并且在基因导向的酶/前体药物治疗完全根除两种不同类型的侵袭性异种移植耐药卵巢肿瘤后。此外，经过对一组自杀基因的仔细筛选，我们已经确定了一种具有抑制复发潜力的酶/前药系统。我们的假设是，新型靶向载体可以在不影响正常器官的情况下，有效地将自杀基因转移到一组异种和同基因卵巢肿瘤中，从而导致原发肿瘤的根除和抑制复发。我们认为，这项研究具有很高的意义，因为它解决了一个重要的问题，即癌症复发。一旦开发出来，这个基于纳米技术的系统可以作为治疗其他类型癌症的平台。这项拨款申请中的拟议研究旨在首先分离CICs并验证靶向和杀伤这些细胞的能力，然后进行广泛的体内生物分布、治疗反应和毒性研究，以证明该系统在治疗各种卵巢肿瘤方面的有效性。这项研究的结果最终可能对癌症患者的存活率产生重大影响，因为它将是 第一种可以有效抑制卵巢癌复发的纳米药物。

DESCRIPTION (provided by applicant): Ovarian cancer is associated with the highest mortality rate of all gynecologic malignancies in US and with an overall 5 years survival rate of 30-40%. Although the majority of tumors initially respond to standard treatments combining surgery and chemotherapy with platinum-based drugs such as cisplatin, but the majority of treated patients acquire multidrug resistance and succumb to their disease due to relapse. It is believed that cancer initiating cells (CICs) also known as cancer stem cells play a major role in tumor recurrence and metastatic spread. Therefore, to inhibit relapse and increase patients' survival rate, it is crucial to design a treatment strategy that during the early stage treatment eradicates both differentiating ovarian cancer cells and CICs. Based on this premise, the primary objective of this research is to develop a targeted therapeutic system that can effectively kill both differentiating cancer cells and CICs and demonstrate not only eradication of the primary tumors but also inhibition of relapse. Solid tumors have complex pathophysiology and factors such as degree of capillary leakiness, extracellular proteins, tumor heterogeneity and tumor cell density significantly limit distribution and efficacy of therapeutic molecules. As a result, a subpopulation of differentiating cancer cells and/or CICs may survive the treatment. To overcome these obstacles and achieve the objective, we have developed a novel highly efficient targeted-shielded nanotechnology platform (vector) that utilizes passive, active and transcriptional targeting mechanisms in order to achieve high anticancer activity at the tumor site with minimal impact on normal tissues. Our live animal imaging and tumor regression studies illustrate that the developed system passively accumulates in tumors, is actively picked up by tumor cells, efficiently transfects and expresses reporter genes specifically in tumors but not other tissues and after gene directed enzyme/prodrug therapy completely eradicates two different types of aggressive xenograft drug resistant ovarian tumors. Furthermore, after careful screening through a panel of suicide genes, we have identified one enzyme/prodrug system that has the potential to inhibit relapse. It is our hypothesis that the novel targeted vector can effectively deliver suicide genes into a panel of xenograft and syngeneic ovarian tumors without affecting normal organs and result in eradication of the primary tumors and inhibition of relapse. We believe that this research is of high significance because it addresses an important problem; i.e., cancer relapse. Once developed, this nanotechnology-based system can be used as a platform for therapy of other types of cancer. The proposed studies in this grant application are designed to first isolate CICs and validate the ability to target and kill these cells followed by n extensive in vivo biodistribution, therapy response and toxicity studies to demonstrate the effectiveness of the system in treating various ovarian tumors. The outcome of this research could ultimately have a significant impact on cancer patients' survival rate because it will be the first nanomedicine that could effectively inhibit ovarian cancer relapse.