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

描述(申请人提供)：某些癌症的治愈率很低，例如肺癌，这是癌症死亡的最常见原因，是一个重要的健康问题。目前，早期发现似乎是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，肺癌通过良性病变和过程模仿其活体图像外观，从而降低了检测的特异性。目前的成像方法包括胸部X光、CT和MRI。虽然这些目前的方法能够识别出可治愈的肺癌，但它们也导致了许多假阳性。他们能够检测到的肺结节的大小也是有限的。使用现有的标准，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，需要提高癌细胞的敏感性和特异性。我们的抗转铁蛋白受体单链抗体片段(TfRscFv)免疫脂质体复合体(Scl)是一种纳米结构(~100 nm)，可用于肿瘤的基因治疗。已经证明，当以异种移植的形式植入小鼠体内时，它可以靶向各种类型的人类肿瘤细胞，目前正在进行wtp53的第一阶段临床试验。我们在这项应用中提出的是诊断准确率的巨大飞跃，这是一种专用于癌症的方法，最适合于肺癌等小癌症。我们正在开发的方法是一种纳米级的免疫脂质体复合体，可以输送超顺磁性氧化铁颗粒(SPIO)。氧化铁颗粒既是顺磁性的，也是超顺磁性的，具有T1和T2*特征的两相响应。这种复合体具有很高的选择性，靶向癌细胞。因此，通过这种应用的SCL-SPIO复合体将SPIO直接高效地输送到肿瘤细胞中，可以增加肺肿瘤细胞的显着性。此外，根据以前的研究，作为这一应用的重点的纳米复合体交付的造影剂应该在癌细胞内积累一段较长的时间(几个小时)，从而使非癌症区域的对比物被洗掉，进一步增强癌症的显着性。在使用尚未优化的SCL-SPIO复合体的初步研究中，我们展示了与游离SPIO相比的肿瘤细胞特异性，并增强了图像强度。更重要的是，在早期用scl与另一种显像剂Gad-d复合的研究中，在肺肿瘤模型中，scl-Gad-d(而不是游离的Gad-d)能够增强和识别小至1-4像素(0.1-0.4 mm)的肺部肿瘤，这一尺寸比目前技术可能的尺寸更小。该络合物未发现任何毒性。在这项应用中，我们将优化scl-SPIO复合体，并充分表征其用于在人类肺癌小鼠模型中早期检测肺癌的能力，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，我们还将评估复合体的磁性，并确定其亚细胞定位和通过细胞的运输。我们的目标是完成提交IND所需的大部分研究，因为我们的目标是迅速走向临床试验。如果癌症被及早发现(例如I期)，在许多情况下可以治愈(较低的死亡率)。挑战是能够在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，肺癌在成像过程中经常被非肿瘤病变模仿，导致不确定性和许多假阳性，这些问题往往只有随着肿瘤的生长才能解决。因此，迫切需要能够提高灵敏度和特异性的显像剂。我们的肿瘤特异性纳米复合制剂，如Gad-d和氧化铁，在这方面的初步研究中显示出巨大的前景，表明其对肺内癌细胞的高亲和力可以提高检测肿瘤的敏感性和整体特异性。开发一种能够更早发现的显像剂是抗癌战争中的重中之重，可能会提高存活率。

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.