EphB4 as Novel Target for Breast Cancer Imaging

描述（由申请人提供）：据估计，2009年有192,370名妇女被诊断患有乳腺癌，40,170名妇女死于无法治愈的转移性乳腺癌。显然，有必要开发针对原发性和转移性乳腺癌的新的诊断和治疗方法。越来越多的证据表明，Eph受体酪氨酸激酶及其细胞表面结合配体Ephrins在癌症进展中起着关键作用。特别是，在小鼠乳腺肿瘤模型和超过一半的人类乳腺癌样本中发现了EphB4表达的上调。EphB4在人类乳腺癌细胞系中也广泛表达，并被发现与乳腺癌患者的生存相关。基于EphB4极其重要的功能，以EphB4为中心的治疗已成为乳腺癌治疗策略的潜在重要组成部分。然而，肿瘤对EphB4抑制的敏感性可能并不统一于所有乳腺癌，包括原发性或转移性乳腺癌。目前迫切需要更好地预测哪些患者和个别肿瘤可能对这种新的干预措施有反应，并监测治疗反应。在本课题中，我们计划开发EphB4特异性PET探针，定量EphB4在乳腺癌异种移植物中的表达。我们假设EphB4的表达水平是预测肿瘤对EphB4抑制治疗反应的决定因素。因此，用适当的放射性标记的EphB4抗体、EphB4抑制剂或EphB4结合肽进行PET成像，将在无创和重复评估EphB4抑制方面具有很高的价值。这种新型成像方法的成功将为乳腺癌提供新的诊断方法，帮助我们更好地预测哪些患者和个体肿瘤可能对针对EphB4的新型干预措施有反应，并使直接监测对治疗干预措施的反应成为可能。在本项目结束时，我们将积累足够的基于动物的转化数据，以提交基于临床的提案。除乳腺癌外，EphB4在黑色素瘤、前列腺癌、结肠癌、膀胱癌、肺癌、间皮瘤、子宫癌和骨肉瘤中也显著过表达。这些新开发的PET探针也可以在这些其他癌症类型中有重要的应用，从而对大量癌症患者产生重大的临床影响。

DESCRIPTION (provided by applicant): It is estimated that 192,370 women were diagnosed with breast cancer in 2009 and 40,170 women died as a result of incurable metastatic breast disease. There is clearly a need to develop new diagnostic and therapeutic methods targeting both primary and metastatic breast cancer. Accumulating evidence suggests that Eph receptor tyrosine kinases and their cell-surface bound ligands, the Ephrins, play key roles in cancer progression. In particular, up-regulation of EphB4 expression has been found in mouse mammary tumor models and in more than half of the human breast cancer specimens examined. EphB4 is also widely expressed in human breast cancer cell lines, and has been found to correlate with survival in breast cancer patients. Based on the extremely important function of EphB4, therapies focusing on EphB4 have become potentially important components of breast cancer treatment strategies. However, tumor sensitivity to EphB4 suppression may not be uniform for all breast cancers, including primary v. metastatic disease. There is an urgent need to better predict which patients and individual tumors are likely to respond to such novel interventions, as well as monitor the therapeutic response. In this proposal, we plan to develop EphB4 specific PET probes, to quantify EphB4 expression in breast cancer xenografts. We hypothesize here that the EphB4 expression level is a determinant factor for predicting a tumor's response to EphB4 suppression therapy. Thus, PET imaging with suitably radiolabeled EphB4 antibodies, EphB4 inhibitors, or EphB4 binding peptides, will be highly valuable in assessing EphB4 suppression non-invasively and repetitively. The success of this novel imaging approach could lead to novel diagnosis method for breast cancer, help us better predict which patients and individual tumors are likely to respond to novel interventions targeting EphB4, and make it possible to direct monitor the responses towards therapeutic interventions. At the conclusion of this project, we will have accumulated sufficient animal-based translational data for submission of a clinically-based proposal. In addition to breast cancer, EphB4 is also significantly over-expressed in melanoma, prostate cancer, colon cancer, bladder cancer, lung cancer, mesothelioma, uterine cancer, and osteosarcoma. These newly developed PET probes could also have important applications in these other cancer types, and thus have a significant clinical impact on a very large number of cancer patients. PUBLIC HEALTH RELEVANCE: Breast cancer is the most frequently diagnosed cancer in women. It is estimated that 192,370 women were diagnosed with breast cancer in 2009 and 40,170 women died as a result of incurable metastatic breast disease. There is clearly a need to develop new diagnostic and therapeutic methods targeting both primary and metastatic breast cancer. The proposed research will develop EphB4 specific PET probes, which would be able to examine the breast cancer onset and progression by quantifying EphB4 expression non-invasively and repetitively. The data obtained from this project will help in many aspects of anti-EphB4 breast cancer therapy, particularly for patient stratification (e.g., selecting EphB4-positive cancer patients for new anti-EphB4 clinical trials while sparing EphB4-negative patients for other treatments), treatment monitoring, and dose optimization. The same probes developed in this project may also have important applications in many other cancer types, and thus have a significant clinical impact on a very large number of cancer patients.