Novel Ovarian Cancer Detection Agents from Phage Display

描述(申请人提供)：就发病率和死亡率而言，卵巢腺癌是美国最大的妇科恶性肿瘤。虽然在早期是可以治疗的，但晚期或转移性卵巢癌通常是致命的。由于卵巢癌在早期通常是无症状的，约70%的患者在确诊时已有晚期或转移性疾病。目前的筛查方法包括超声检查、盆腔检查和血清CA125筛查。不幸的是，这些检查并不是卵巢癌的特异性检查，需要侵入性手术活检才能做出正确的诊断。改善早期诊断和治疗将来自一种更直接的方法，即针对卵巢肿瘤细胞或其上过度表达的抗原进行靶向。由于噬菌体(噬菌体)展示方法的实施，新的基于多肽的分子探针正在迅速演变，以促进癌症检测和成像。我们以前开发了新的体内噬菌体展示筛选技术来识别针对多种类型的癌症的多肽，包括乳腺癌和前列腺癌。然而，人们观察到，通过噬菌体展示鉴定的大多数合成肽，虽然在体外表现出良好的结合性能，但无法在活体动物中成像肿瘤。根据我们的经验，合成肽是一种成功的显像剂，是从展示了体内肿瘤靶向特性的噬菌体中提取出来的。在这里，假设在体内选择的噬菌体，在人类卵巢肿瘤荷瘤小鼠中，一旦被荧光标记，就可以很容易地在体内重新筛选肿瘤归巢倾向，从而简化基于多肽的卵巢癌成像和治疗药物的开发过程。将使用单光子发射计算机断层扫描(SPECT)检查识别的多肽的放射性标记版本是否具有对小鼠卵巢肿瘤进行成像的能力。在这项提案中，我们在噬菌体展示、肿瘤学、成像和多肽放射化学方面的专业知识将整合在一起，为卵巢癌检测提供新的肿瘤抗原特异性噬菌体颗粒和多肽。创新的体内噬菌体筛选被提出，以加快新的基于多肽的肿瘤显像剂的发现过程。这项工作的长期目标是将放射性多肽转化为临床，用于卵巢癌的非侵入性筛查和检测。具体地说，我们建议通过在人卵巢癌荷瘤小鼠体内进行噬菌体展示选择来获得新的卵巢癌靶向性多肽。其次，从筛选中选择的噬菌体将被荧光标记并用于体内光学成像屏幕，以加快发现新的卵巢肿瘤显像剂。最后，将合成与体内成像性能最佳的噬菌体相对应的多肽，并用111In和99mTc对其进行放射性标记，并在体内检测其SPECT成像效果。描述了新的噬菌体展示和多肽放射化学方法来促进卵巢癌的检测，卵巢癌是一种值得更多研究和关注的癌症。 新的卵巢选择性肿瘤靶向药物的发现和实施有可能提高诊断效率和影响疾病治疗，从而改善患者的就诊情况，并用微创卵巢诊断药物取代高侵入性的手术。

DESCRIPTION (provided by applicant): Ovarian adenocarcinomas are the largest class of gynecologic malignancies in the United States with respect to incidence and mortality. While treatable in their earliest stage, advanced or metastatic forms of ovarian cancer are usually deadly. Because ovarian cancer is often asymptomatic in its early stages, ~70% of patients have advanced or metastatic disease at time of diagnosis. Current screening methods include ultrasonography, pelvic exam, and serum screening for CA125. Unfortunately, these tests are not specific for ovarian cancer and invasive surgical biopsy is required for proper diagnosis. Improved early diagnosis and therapy will result from a more directed approach in which antigens specific to or overexpressed on ovarian tumor cells are targeted. New peptide-based molecular probes to facilitate cancer detection and imaging are rapidly evolving due to implementation of bacteriophage (phage) display approaches. We previously developed novel in vivo phage display screening techniques to identify peptides that target numerous types of cancers including those of the breast and prostate. However, it was observed that the majority of the synthesized peptides identified by phage display, while exhibiting excellent in vitro binding properties, failed to image tumors in living animals. It has been our experience that synthetic peptides, which were successful imaging agents, were derived from phage that had demonstrated in vivo tumor target properties. Here, it is hypothesized that phage selected in vivo, in human ovarian tumor-bearing mice, once fluorescently labeled, can be easily re-screened in vivo for tumor-homing propensity, thus streamlining the process of development of peptide-based ovarian cancer imaging and therapeutic agents. Radiolabeled versions of the identified peptides will be examined for their ability to image ovarian tumors in mice using Single Photon Emission Computed Tomography (SPECT). In this proposal, our expertise in phage display, oncology, imaging, and peptide radiochemistry will be integrated to provide novel tumor antigen-specific phage particles and peptides for ovarian cancer detection. Innovative in vivo phage screens are proposed to expedite the process of discovery of new peptide-based tumor imaging agents. A long-term goal of this work is to translate the radiolabled peptides into the clinic for the non-invasive screening and detection of ovarian cancer. Specifically we propose to obtain new classes of ovarian cancer targeting peptides by performing in vivo phage display selections in human ovarian carcinoma-bearing mice. Second, phage selected from the screens will be fluorescently labeled and employed in in vivo optical imaging screens to expedite discovery of new ovarian tumor imaging agents. Last, peptides corresponding to phage with optimal in vivo imaging properties will be synthesized and radiolabled with 111In and 99mTc and examined for their SPECT imaging efficacy in vivo. Novel phage display and peptide radiochemistry approaches are described to advance the detection of ovarian cancer a cancer that deserves much more research and attention. PUBLIC HEALTH RELEVANCE The discovery and implementation of novel ovarian selective tumor targeting agents has the potential to improve diagnostic efficacy and impact disease treatment thus improving patient comes and replacing highly invasive procedures with minimally invasive ovarian diagnostic agents.