Relevance of circulating mutant BRAF DNA in melanoma

描述（由申请人提供）：BRAF癌基因突变的高频率及其基因产物在转移性黑色素瘤发病机制中的关键作用导致了目前正在进行临床试验的BRAF抑制剂疗法的开发。我们正在参与两项这样的试验（一项在我们的机构测试BAY 43-9006，另一项与纪念斯隆-凯特琳癌症中心合作测试17-AAG），这些试验要求患者接受转移性病变的活检以进行BRAF基因测序，以符合参与资格。因此，许多患者由于其转移瘤的不可及性而不适合BRAF抑制剂。因此，迫切需要开发一种简单的BRAF基因分型机制，以改善适合抗BRAF治疗的患者的选择。我们已经开发了一种新的，敏感的，特异的，基于DNA的，荧光检测突变BRAF等位基因在外周血和黑色素瘤患者的肿瘤标本。在我们的初步分析中，我们能够在13/23（57%）例患者血液标本中检测到突变BRAF等位基因。我们提案的目的是确定这种创新检测在明确定义的患者队列中的临床效用。在目的1中，我们将比较淋巴结转移（III期）与内脏部位转移（IV期）的黑色素瘤患者外周血中突变BRAF等位基因的检测频率。此外，我们将基于完善的标准临床指标（如肿瘤扩散模式和转移灶数量）确定血液中突变BRAF等位基因检测与疾病负担之间的关联。在目标2中，我们将确定目标1中分析的患者的血液和相应肿瘤组织中突变BRAF状态之间的一致性水平。我们预见我们的项目是建立这种外周血测定在选择有资格接受BRAF抑制剂治疗的黑色素瘤患者中的实用性的关键步骤，并且可能在监测对治疗的反应中。

DESCRIPTION (provided by applicant): The high frequency of BRAF oncogene mutations coupled with the critical role of its gene product in the pathogenesis of metastatic melanoma have led to the development of BRAF inhibitor therapies that are currently undergoing clinical trials. We are participating in two such trials, (one at our institution testing BAY 43-9006, and the other collaborating with Memorial Sloan-Kettering Cancer Center testing 17-AAG) which require that the patients undergo biopsy of their metastatic lesion for sequencing of the BRAF gene to be eligible for participation. As a result, many patients are ineligible for BRAF inhibitors due to inaccessibility of their metastases. Thus, there is an urgent need to develop a simple mechanism for BRAF genotyping to improve selection of patients who are eligible for anti-BRAF therapies. We have developed a new, sensitive, specific, DNA-based, fluorescent assay to detect mutant BRAF alleles in the peripheral blood and tumor specimens of melanoma patients. In our preliminary analyses, we were able to detect mutant BRAF alleles in 13/23 (57%) patient blood specimens. The objective of our proposal is to define the clinical utility of this innovative assay in well-defined patient cohorts. In Aim 1, we will compare the frequency of detection of mutant BRAF alleles in the peripheral blood of melanoma patients with lymph node metastases (Stage III) to those with metastases to visceral sites (Stage IV). In addition, we will determine the association between detection of mutant BRAF alleles in the blood and disease burden based on well-established, standard clinical measures such as pattern of tumor spread and the number of metastatic sties. In Aim 2, we will determine the level of concordance between mutational BRAF status in the blood and corresponding tumor tissues from the patients analyzed in Aim 1. We foresee our project as a critical step in establishing the utility of this peripheral blood assay in selecting melanoma patients eligible to receive BRAF inhibitor therapy, and, potentially, in monitoring response to treatment.