Circulating Tumor Cell Capture & Analysis in a Multi-Center Prostate Cancer Trial

描述(申请人提供)：前列腺癌是美国男性最常见的恶性肿瘤，也是癌症死亡率第二高的原因。迫切需要新的预测和预测生物标记物来更好地指导我们的治疗决定。最近的研究表明，外周血循环肿瘤细胞(CTCs)的定量可以预测晚期前列腺癌的治疗反应和总体生存。然而，目前的四氯化碳采集方法受到产量低、技术复杂和设备昂贵的限制，而且它们提供的关于四氯化碳本身的表型信息很少。为了解决这些局限性，我们开发了一种新的微过滤设备，该设备安装在普通注射器上，可以可靠地捕获和丰富外周血中的CTC群体，从而能够计数和进一步研究这些细胞，如表征治疗靶点。我们的假设是，CTC的定量和表征可以在治疗方案的早期确定预后和预测治疗反应，微过滤器可以作为一个简单但可靠的新平台，用于大规模临床试验中CTC的收集、定量和表型分析。为了验证这一假说，我们提出了一项相关研究，将“搭载”到S0421，S0421是一个活跃的SWOG合作小组方案，研究阿特拉森坦与多西他赛联合治疗去势抵抗前列腺癌。这项提议已经得到SWOG的审查，并获得了行政部门的批准。在S0421预先指定的3个时间点，治疗前(第1天)和治疗期间(第21天和63天，即4次治疗中的第2次和第4次治疗时)，采血样本通过微滤装置进行处理，并对捕获的CTC进行分析，以解决以下具体目标：1.CTC绝对计数和治疗后CTC计数的变化是否准确地预测临床结果和治疗反应？作为微过滤器捕获CTC的进一步验证，平行样本将使用FDA批准的细胞搜索CTC收集平台进行分析；2.微过滤器捕获的CTC上相关生物标记物的表达是否预测临床结果和治疗反应？我们将专门评估内皮素受体A对阿特拉森坦的反应，III型2-微管蛋白对多西紫杉醇的反应，CD44对侵袭性祖细胞/转移表型的影响；以及3.微滤浓缩细胞中端粒酶活性(一种已建立的癌症标记物)的存在和水平是否与捕获的CTCs的存在和数量有关，以及它是否可以用于预测临床结果和治疗反应？总之，我们的目标将是确定在我们的新平台上捕获的CTC的数量和特征是否可以预测S0421中的临床结果和治疗反应。最终，这项研究的结果将为我们的前列腺癌治疗决策提供重要信息，并大大增强我们实时评估治疗效果的能力，从而构成朝着优化、基于证据的个性化患者管理迈出的一大步。公共卫生相关性：我们建议量化和表征外周血循环肿瘤细胞(CTCs)作为预测晚期前列腺癌治疗反应和生存的标志物，使用一种新型微过滤设备，该设备可以捕获和丰富参加SWOG临床试验的患者的循环CTCs，S0421。我们将分析微滤浓缩的CTC中的CTC计数、相关生物标记物的表达和端粒酶活性(一种已建立的癌症标记物)是否可以预测结果和治疗反应。我们期望这项研究将大大帮助前列腺癌的治疗，并加强对治疗效果的实时评估。

DESCRIPTION (provided by applicant): Prostate cancer is the most common malignancy and the second highest cause of cancer mortality in American men. New prognostic and predictive biomarkers are urgently needed to better inform our treatment decisions. Recent studies have demonstrated that quantification of peripheral blood circulating tumor cells (CTCs) predicts response to therapy and overall survival in advanced prostate cancer. However, present methods for CTC collection are limited by low yield, complex techniques, and expensive equipment, and they provide little phenotypic information about the CTCs themselves. To address these limitations, we have developed a new microfilter device that is fitted to an ordinary syringe and reliably traps and enriches the CTC population from peripheral blood, enabling enumeration and further study of these cells, such as characterization of therapeutic targets. It is our hypothesis that quantification and characterization of CTC can determine prognosis and predict response to therapy early in the course of the therapeutic regimen, and that the microfilter can serve as a simple yet reliable new platform for CTC collection, quantification, and phenotypic analysis in a large clinical trial setting. To test this hypothesis, we propose a correlative study that would "piggyback" onto S0421, an active SWOG cooperative group protocol studying atrasentan in combination with docetaxel in castration resistant prostate cancer. This proposal has been reviewed by SWOG and has received executive approval. At 3 time points pre-designated by S0421, pre-treatment (day 1) and during treatment (days 21 and 63, that is at the time of the second and fourth of 4 treatments), blood samples will be drawn and processed through the microfilter device, and the captured CTCs will be analyzed to address the following specific aims: 1. Do absolute CTC counts and post-treatment changes in CTC counts accurately predict clinical outcome and response to therapy? As further validation of microfilter CTC capture, parallel samples will be analyzed using the FDA approved Cell Search CTC collection platform; 2. Does the expression of relevant biomarkers on microfilter-trapped CTCs predict clinical outcome and response to therapy? We will specifically assess endothelin receptor A for atrasentan response, type III 2-tubulin for docetaxel response, and CD44 for an aggressive progenitor/metastatic phenotype; and 3. Does the presence and level of telomerase activity (an established cancer marker) in microfilter-enriched cells correlate with the presence and number of captured CTCs, and can it be used to predict clinical outcome and response to therapy? In summary, our goal will be to determine if the quantity and characteristics of CTCs captured on our novel platform can predict clinical outcome and response to therapy in S0421. Ultimately, the results of this study will significantly inform our treatment decisions in prostate cancer and profoundly enhance our ability to assess therapeutic efficacy in real time, thus constituting a major stride towards optimized, evidence-based, individualized patient management. PUBLIC HEALTH RELEVANCE: We propose to quantify and characterize peripheral blood circulating tumor cells (CTCs) as a marker to predict therapeutic response and survival in advanced prostate cancer using a novel microfilter device that traps and enriches circulating CTCs in patients enrolled in the SWOG clinical trial, S0421. We will analyze if CTC counts, expression of relevant biomarkers, and telomerase activity (an established cancer marker) in microfilter- enriched CTCs can predict outcome and response to therapy. We expect this study to significantly help prostate cancer management and enhance real time assessment of therapeutic efficacy.