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BRAF抑制剂治疗的发展，目前正在进行临床试验。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），这两项试验要求患者对其转移灶进行活检以进行BRAF基因测序，才有资格参加试验。因此，许多患者由于其转移灶难以接近而不适合使用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。我们开发了一种新的、敏感的、特异性的、基于dna的荧光检测方法，用于检测黑色素瘤患者外周血和肿瘤标本中的突变BRAF等位基因。在我们的初步分析中，我们能够在13/23（57%）患者血液样本中检测到突变BRAF等位基因。我们建议的目标是在明确的患者队列中定义这种创新检测的临床效用。在Aim 1中，我们将比较淋巴结转移（III期）和转移到内脏部位（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，我们将确定血液中突变BRAF等位基因的检测与疾病负担之间的关系，基于完善的，标准的临床措施，如肿瘤扩散模式和转移瘤的数量。在Aim 2中，我们将确定血液中突变BRAF状态与Aim 1中分析的患者的相应肿瘤组织之间的一致性水平。我们预计我们的项目将是建立这种外周血检测在选择有资格接受BRAF抑制剂治疗的黑色素瘤患者中的实用性的关键一步，并有可能监测对治疗的反应。

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.