Mechanisms of Venous Thromboembolism in Cancer

描述（由申请人提供）： 静脉血栓栓塞（VTE）是癌症患者死亡和残疾的主要原因。抗肿瘤药物（如化疗药物吉西他滨和顺铂）以及联合治疗进一步增加了这些患者的VTE发生率。然而，癌症患者中VTE的机制在很大程度上是未知的。本提案的总体目标是确定胰腺癌或结肠癌患者以及荷瘤小鼠中循环微粒（MP）中的组织因子（TF）活性与静脉血栓形成之间是否存在关联。MP是从活化或凋亡细胞释放的小（<1微米）膜囊泡。我们的一般假设是，化疗药物增加TF阳性MP从肿瘤细胞和宿主细胞释放到循环中，并且这些MP水平的增加与胰腺癌和结肠癌患者中无症状和有症状的VTE的发生率增加以及荷瘤小鼠中血栓大小的增加相关。该提案分为两个目标。在具体目标1中，我们将确定用化疗药物治疗荷瘤小鼠对来自肿瘤细胞和不同宿主细胞的循环TF阳性MP的影响，以及它们在静脉血栓形成模型中的作用。我们将测量用吉西他滨或吉西他滨和顺铂治疗的荷瘤小鼠中分离的MP中的TF活性水平。我们将使用一系列新的小鼠系来区分源自i/肿瘤与宿主细胞和ii/不同宿主细胞（单核细胞、内皮细胞和血小板）的TF阳性MP。这些包括HCV小鼠，其在不存在小鼠TF的情况下表达人TF，以及使用Cre-loxP技术产生的具有TF基因的各种细胞类型特异性缺失的小鼠。最后，我们将选择性地分析肿瘤细胞衍生的或宿主细胞衍生的TF阳性MP在静脉血栓形成模型中的作用。在特定目标2中，我们将在一项多中心前瞻性观察性研究中确定循环MP中的TF活性与接受抗肿瘤药物治疗的晚期胰腺癌和结肠癌患者的VTE之间是否存在关联。将在抗肿瘤药物治疗前后采集患者的血液样本。在抗肿瘤药物治疗前后，将使用压缩超声评估无症状深静脉血栓形成。我们将测量孤立MP的TF活性水平，并确定这是否与无症状和/或有症状的VTE相关。我们还将测量全血TF活性、TF阳性MP的细胞来源和凝血活化标志物（凝血酶抗凝血酶复合物和D-二聚体）。本研究的结果将确定TF阳性MP在与癌症和化疗相关的静脉血栓形成中的作用。分离的MP中的TF活性可能是一种有用的生物标志物，其可以单独使用或作为接受化疗的癌症患者中血栓形成风险的临床预测模型中的连续生物标志物。公共卫生相关性：静脉血栓形成或静脉血栓形成是癌症患者死亡和残疾的主要原因。众所周知，潜在的癌症和用于治疗的化疗都会增加静脉血栓形成的风险。本研究计划的目标是研究癌症和抗癌药物治疗癌症导致血栓形成的机制。我们还将确定血液中一种重要的凝血蛋白（称为组织因子）的增加是否与癌症患者的血栓形成有关，如果是这样，它是否可以用来预测哪些癌症患者的血栓风险增加。这是非常重要的，因为医生将能够制定措施，以防止高风险患者的血栓形成，并改善临床结果。

DESCRIPTION (provided by applicant): Venous thromboembolism (VTE) is a leading cause of death and disability in cancer patients. The incidence of VTE in these patients in further increased by the administration of anti-neoplastic drugs, such as the chemotherapy drugs gemcitabine and cisplatin, as well as combination therapies. However, the mechanisms of VTE in cancer patients are largely unknown. The overall goal of this proposal is to determine whether an association exists between tissue factor (TF) activity in circulating microparticles (MPs) and venous thrombosis in patients with pancreatic or colon cancer, and in tumor-bearing mice. MPs are small (<1 micron) membrane vesicles that are released from activated or apoptotic cells. Our general hypothesis is that chemotherapy drugs increase the release of TF-positive MPs from both tumor cells and host cells into the circulation, and that an increase in the level of these MPs is associated with an increase in the incidence of asymptomatic and symptomatic VTE in pancreatic and colon cancer patients, and an increase in thrombus size in tumor-bearing mice. The proposal is divided into two aims. In Specific Aim 1 we will determine the effect of treatment of tumor-bearing mice with chemotherapeutic drugs on circulating TF-positive MPs derived from tumor cells and different host cells as well as their role in a model of venous thrombosis. We will measure the levels of TF activity in isolated MPs in tumor-bearing mice treated with either gemcitabine or gemcitabine and cisplatin. We will use a series of novel mouse lines to distinguish between TF-positive MPs derived from i/ tumor versus host cells, and ii/ different host cells (monocytes, endothelial cells and platelets). These include HCV mice, which express human TF in the absence of mouse TF, and mice with various cell type-specific deletions of the TF gene generated using the Cre-loxP technology. Finally, we will selectively analyze the role of either tumor cell- derived or host cell-derived TF-positive MPs in a model of venous thrombosis. In Specific Aim 2 we will determine if there is an association between TF activity in circulating MPs and VTE in patients with advanced pancreatic and colon cancer treated with anti-neoplastic drugs in a multi-center prospective observational study. Blood samples will be obtained from patients before and after treatment with anti-neoplastic drugs. Asymptomatic deep vein thrombosis will be assessed using compression ultrasound before and after treatment with anti-neoplastic drugs. We will measure levels of TF activity in isolated MPs and determine if this is associated with asymptomatic and/or symptomatic VTE. We will also measure whole blood TF activity, cellular origin of the TF-positive MPs and coagulation activation markers (thrombin anti thrombin complexes and D- dimer). The results of this study will determine the role of TF-positive MPs in venous thrombosis associated with cancer and chemotherapy. TF activity in isolated MPs may be a useful biomarker that can be used either alone or as an adjunctive biomarker in clinical predictive models of thrombotic risk in cancer patients undergoing chemotherapy. Public Health Relevance: Development of blood clots in veins or venous thrombosis is a leading cause of death and disability among cancer patients. Both the underlying cancer and the chemotherapy used to treat it are known to increase the risk of venous thrombosis. It is the goal of this research proposal to study the mechanism by which cancer and treatment of cancer with anti-cancer drugs lead to development of blood clots. We will also determine if increase in an important clotting protein in the blood (called tissue factor) is associated with development of blood clots in cancer patients, and if so, whether it could be used to predict which cancer patients are at increased risk for blood clots. This is of enormous importance as physicians will be able to institute measures to prevent thrombosis in high-risk patients and improve clinical outcomes.