Nanoimmunoliposome-Complexed SPIO: Tumor-Specific Detection of Early Lung Cancer

描述（由申请人提供）：某些癌症，如肺癌，是癌症死亡的最常见原因，治愈率低，是一个重要的健康问题。早期发现似乎是目前改善高死亡率的唯一途径，但由于早期疾病缺乏症状，因此相当困难。此外，肺癌在其体内图像外观中被良性病变和降低检测特异性的过程模仿。目前的成像方法包括胸部X射线、CT和MRI。虽然这些目前的方法能够识别可治愈的肺癌，但它们也导致许多假阳性。他们也在他们可以检测到的肺结节的大小方面受到限制。使用现有标准，肺癌检测的敏感性很高，但特异性和阳性预测值仅为中等。因此，需要增强对癌细胞的敏感性和特异性。我们的抗转铁蛋白受体scFv-抗体片段（TfRscFv）免疫脂质体复合物（scL）是一种用于向肿瘤递送基因治疗的纳米构建体（~100 nm）。当作为异种移植物植入小鼠体内时，它已被证明在体内靶向各种类型的人类肿瘤细胞，并且现在处于递送wtp 53的I期临床试验中。我们在这个应用中提出的是诊断准确性的量子跳跃，这是一种针对癌症的方法，最适合肺癌等小癌症。我们正在开发的方法是一种纳米级的免疫脂质体复合物提供超顺磁性氧化铁颗粒（SPIO）。氧化铁颗粒是顺磁性和超顺磁性的，产生具有T1和T2* 特征的双相响应。这种复合物以高选择性靶向癌细胞。因此，通过本申请的scL-SPIO复合物将SPIO直接有效递送到肿瘤细胞中可以增加肺肿瘤细胞的显著性。此外，基于先前的研究，作为本申请的焦点的纳米复合物递送的造影剂应该在癌细胞自身内积累，保持延长的时间段（数小时），从而允许非癌区域中的造影剂被洗掉，进一步增强癌症的显著性。在使用尚未优化的scL-SPIO复合物的初步研究中，我们证明了与游离SPIO相比的肿瘤细胞特异性，并增强了图像强度。更重要的是，在早期的研究中，scL与另一种成像剂gadopentate dimeglumine（gad-d）复合，在肺肿瘤模型中，scL-gad-d（而不是游离gad-d）能够增强和识别小至1-4像素（0.1-0.4mm）的肺肿瘤，尺寸小于现有技术。未发现该复合物的毒性。在本申请中，我们将优化scL-SPIO复合物，并充分表征其用于人类肺癌小鼠模型中肺癌早期检测的能力，并将我们的研究扩展到原发性肺癌小鼠模型。与NIST和NCI的研究人员合作，我们还将评估复合物的磁性，并确定其亚细胞定位和通过细胞的运输。我们的目标是执行提交IND所需的大部分研究，因为我们的目标是快速走向临床试验。如果癌症被早期发现（例如I期），在许多情况下可以治愈（死亡率较低）。挑战在于能够在这个早期阶段发现并积极识别癌症，特别是肺癌。虽然目前的检测方法很好，但它们只能检测到一定大小的肿瘤。此外，肺癌在成像期间经常被非癌性病变模仿，导致不确定性和许多假阳性，这些假阳性通常只能通过跟踪肿瘤的生长来解决。因此，迫切需要增加灵敏度和特异性的成像剂。我们的肿瘤特异性纳米复合物递送MR成像剂，例如gad-d和氧化铁，在我们的初步研究中显示了很大的希望，表明其对肺中癌细胞的高亲和力可以提高检测肿瘤的灵敏度和总体特异性。开发一种可以早期检测的成像剂是抗癌战争的一个高度优先事项，并可能导致生存率的提高。

DESCRIPTION (provided by applicant): The low rate of cure of certain cancers such as lung cancer, the most common causes of cancer death, is an important health problem. Early detection appears currently to be the only way of improving the high mortality rate, but is quite difficult because of the lack of symptoms in early disease. Moreover, lung cancer is mimicked in its in vivo image appearance by benign lesions and processes that lower the specificity of detection. Current imaging methods include chest x-ray, CT, and MRI. While these current methods are able to identify curable lung cancer they also result in many false positives. They are also limited in the size of the lung nodules they can detect. Using available criteria, sensitivity for lung cancer detection is high, but specificity and positive predictive value are only moderate. Thus there is a need for enhanced sensitivity and specificity for cancer cells. Our Anti-transferrin Receptor scFv-antibody fragment (TfRscFv) immunoliposome complex (scL) is a nanoconstruct (~100 nm) for delivery of gene therapy to tumors. It has been shown to target various types of human tumor cells in vivo when implanted as xenografts in mice and is now in Phase I clinical trials for delivery of wtp53. What we are proposing in this application is a quantum jump in diagnostic accuracy, an approach specific to cancer and best for small cancers such as lung cancer. The method we are developing is a nano- sized immunoliposome complex delivering superparamagnetic iron oxide particles (SPIO). Iron Oxide particles are both paramagnetic and super-paramagnetic, giving a biphasic response with both T1 and T2* features. This complex targets cancer cells with high selectivity. Thus the efficient delivery of SPIO directly into the tumor cells by the scL-SPIO complex of this application can increase the conspicuity of the lung tumor cells. Moreover, based on previous studies, the nanocomplex delivered contrast agent which is the focus of this application should accumulate within the cancer cells themselves remaining for an extended period (hours) allowing the contrast in non-cancer areas to wash out, further enhancing cancer conspicuity. In preliminary studies using an as yet unoptimized scL-SPIO complex, we demonstrated tumor cell specificity as compared to free SPIO, and enhanced image intensity. More importantly, in earlier studies with scL complexed with another imaging agent, gadopentate dimeglumine (gad-d), in a lung tumor model, the scL-gad-d (and not free gad-d) was able to enhance and identify lung tumors as small as 1-4 pixels (0.1-0.4mm), a size smaller than possible with current technology. No toxicity was found with this complex. In this application we will optimize the scL- SPIO complex and fully characterize its capabilities for use in early detection of lung cancer in a mouse model of human lung cancer and extend our studies to a mouse model of primary lung cancer. In collaboration with investigators at NIST and NCI we will also asses the magnetic properties of the complex and determine it sub cellular localization and trafficking through the cell. Our goal is to perform the majority of the studies necessary for filing an IND as we aim to move rapidly towards clinical trials. If cancer is detected early (e.g. Stage I), it can in many instances be cured (lower mortality). The challenge is to be able to find and positively identify the cancer at this early stage, particularly lung cancer. While the current methods of detection are good, they can only detect tumors of a certain size. Moreover, lung cancer is often mimicked during imaging by non-cancerous lesions, resulting in uncertainty and many false positives, which are often resolved only by following growth of the tumor. Thus there is a pressing need for imaging agents that increase sensitivity and specificity. Our tumor-specific nano complex delivery of an MR imaging agent, e.g. gad-d and iron oxide, has shown great promise in our preliminary studies in this regard, demonstrating that its high affinity for cancer cells in the lung can result in improved sensitivity in detecting tumors and in overall specificity. The development of an imaging agent that can lead to earlier detection is a high priority in the war on cancer and could lead to increased survival.