Radiohybridization Imaging of HER2 Oncogene to Detect Breast Cancer

描述(申请人提供)：侵袭性、浸润性乳腺癌将在2007年侵袭美国18万名妇女，夺走40,000名妇女的生命。乳房X光检查发现乳房内有肿块，其中80%是良性的，20%是恶性的。对肿块进行活检以确定它们是良性的还是恶性的。但活组织检查不能确定哪些癌基因被激活，也不能可靠地诊断雌激素依赖型乳腺癌和非雌激素依赖型乳腺癌。由于癌症基因的突变激活，恶性肿块中的细胞经常分裂。我们设计并演示了一种新技术，可以从体外观察高度活跃的癌症基因，我们称之为放射杂交成像(RHI)。RHI扫描整个乳房，寻找癌症基因激活的所有位置，无论是否形成肿块。RHI探针是与从激活的癌症基因复制的信使RNA(MRNAs)特异杂交的多肽核酸(PNA)序列。我们添加了一种小肽类似物，使RHI探针能够被乳腺癌细胞摄取。最后，我们将放射性核素进行螯合，通过正电子发射断层扫描(PET)进行外部成像。将针对CCND1、IRS1、MYCC和KRAS mRNAs的RHI探针注入动物模型，使我们能够可视化乳腺癌、胰腺癌和前列腺癌的异种移植。高水平的人类表皮生长因子受体2(Her2)蛋白与侵袭性、侵袭性、雌激素非依赖性乳腺癌有关。HER2信使核糖核酸的测定表明，Her2+乳腺癌细胞每个细胞表达数千个HER2mRNAs，而Her2-乳腺癌细胞表达的HER2mRNAs要少得多。我们假设，HER2癌基因表达的体外放射杂交成像将无创性地检测到侵袭性Her2+乳腺癌，从而能够更快、更准确、更具成本效益地诊断。阶段1：里程碑1：我们将合成和纯化HER2 mRNA RHI试剂和错配对照，使其纯度达到E95%。里程碑2：我们将确定HER2mRNA RHI试剂在培养的人Her2+乳腺癌细胞中是否会显示E3倍的积累，而不是错配对照。阶段2：里程碑1：我们将通过在很大范围内改变HER2+和Her2-乳腺癌移植瘤的比活性来优化HER2 mRNA RHI试剂与错配对照的敏感性，以便在移植瘤中实现比正常对侧组织高E3倍的PET图像对比度。里程碑2：我们将确定在大环络合剂、寡聚酶和IGF1类似物中，哪种药物可以将非特异性器官摄取减少e2倍。里程碑3：我们将确定在发生自发性乳腺癌的Her2+转基因小鼠中，化疗后HER2 mRNA的放射杂交成像是否会显示肿瘤中的PET图像对比度比正常对侧组织减少e2倍，作为对化疗抑制增殖的反应。HER2mRNA水平的RHI测量将与FDG的代谢活性测量进行比较。公共卫生相关性：我们建议开发一种基因核医学程序，从体外检测过度活跃的乳腺癌基因。我们打算在形成肿瘤之前识别出正在发展中的乳腺癌。在动物模型中，我们将测试来自真正良性组织的乳腺癌基因信号的可能性，以及来自真正恶性组织的乳腺癌基因信号缺失的可能性。在未来，对多个乳腺癌基因进行成像可能会诊断雌激素依赖型乳腺癌和非雌激素依赖型乳腺癌，而不需要进行侵入性手术。

DESCRIPTION (provided by applicant): Aggressive, invasive breast cancer will attack >180,000 women in the US in 2007, and will take the lives of >40,000 women. Mammograms detect lumps in breasts, H80% of which are benign, and H20% are malignant. Lumps are biopsied to determine whether they are benign or malignant. But biopsies do not determine which oncogenes are activated, and do not reliably diagnose estrogen-dependent vs. estrogen-independent breast cancer. The cells in malignant lumps divide frequently due to mutational activation of cancer genes. We have designed and demonstrated a novel technology to see visualize hyperactive cancer genes from outside the body, which we call radiohybridization imaging (RHI). RHI scans the entire breast to find all sites of cancer gene activation, whether or not a lump has formed. RHI probes are peptide nucleic acid (PNA) sequences that hybridize specifically to messenger RNAs (mRNAs) copied from activated cancer genes. We added a small peptide analog to allow the RHI probes to be taken up by the breast cancer cells. Finally, we chelated radionuclides to permit external imaging by positron emission tomography (PET) scanning. RHI probes for CCND1, IRS1, MYCC, and KRAS mRNAs, injected into animal models, enabled us to visualize breast cancer, pancreas cancer, and prostate cancer xenografts. High levels of human epidermal growth factor receptor 2 (Her2) protein are associated with aggressive, invasive, estrogen-independent breast cancers. Measurements of HER2 mRNA demonstrated that Her2+ breast cancer cells express thousands of HER2 mRNAs per cell, while Her2- breast cancer cells express much less. We hypothesize that external radiohybridization imaging of HER2 oncogene expression will detect aggressive Her2+ breast cancers noninvasively, enabling faster, more accurate, more cost-effective diagnosis. Phase 1: Milestone 1: We will synthesize and purify a HER2 mRNA RHI agent and mismatch controls to e95% purity. Milestone 2: We will determine whether or not the HER2 mRNA RHI agent will show e3-fold greater accumulation in human Her2+ breast cancer cells in culture, vs. mismatch controls. Phase 2: Milestone 1: We will optimize the sensitivity of the HER2 mRNA RHI agent, vs. mismatch controls, in human Her2+ and Her2- breast cancer xenografts by varying the specific activity over a wide range, in order to achieve e3-fold greater PET image contrast in the xenografts, relative to normal contralateral tissue. Milestone 2: We will determine which agent, among macrocyclic chelators, oligolysines, and IGF1 analogs, will reduce nonspecific organ uptake by e2-fold. Milestone 3: We will determine whether radiohybridization imaging of HER2 mRNA following chemotherapy in Her2+ transgenic mice that develop spontaneous breast cancers will show e2-fold decrease in PET image contrast in the tumor, relative to normal contralateral tissue, vs. Her2- control mice, as a response to chemotherapeutic interdiction of proliferation. RHI measurement of HER2 mRNA levels will be compared with FDG measurement of metabolic activity over time. PUBLIC HEALTH RELEVANCE: We propose to develop a genetic nuclear medicine procedure to detect hyperactive breast cancer genes from outside the body. We intend to identify developing breast cancers before they form a tumor. In animal models, we will test for the possibility of breast cancer gene signals from tissues that are really benign, and for lack of breast cancer gene signals from tissues that are really malignant. In the future, imaging multiple breast cancer genes might diagnose estrogen-dependent vs. estrogen-independent breast cancer without an invasive procedure.