Overcoming Resistance to RAF Inhibition in BRAF-Mutant Colorectal Cancer

BRAF癌基因突变是结直肠癌（CRC）的常见事件。这些突变 与不良结局和对基于表皮生长因子受体（EGFR）的 疗法而RAF抑制剂已成功治疗BRAF突变型恶性肿瘤， 在黑色素瘤中，BRAF突变型CRC的应答率令人惊讶地低。这些不同的基础 治疗结果仍不完全清楚。我们小组的初步研究发现， PLX 4720对MAPK途径的抑制在CRC细胞系中是不完全的。在某些情况下，这可能是由于 增强的EGFR依赖性信号，但这并不能解释这种情况下的所有阻力。我们 目的是确定BRAF突变型结直肠癌中赋予新生耐药的机制 RAF抑制剂，希望能够实现更有效的治疗。第一，差异表达基因 与BRAF突变型CRC相关的基因将通过TCGA数据集的分析来鉴定;这些基因将被 与那些基于正在进行的系统性研究而改变对MAPK通路抑制剂反应的药物相结合。 功能屏幕。排名靠前的基因将进行机制研究，以阐明分子机制。 他们赋予抵抗力的基础，同时，正在进行的功能筛选将扩大到识别 在BRAF突变结肠直肠细胞中，RAF抑制是合成致死的基因。在这里，验证 领先的候选人将优先考虑潜在的药物基因-几个候选人已经 已经被提名了。将在细胞中探索靶向药物与RAF抑制剂的合理组合。 培养和异种移植模型中。最后，将进行联合RAF和MEK抑制剂的临床试验 在DF/HCC中，试图通过增强MAPK通路的抑制来提高疗效， 防止耐药性的出现。将在治疗前、治疗中和治疗后收集肿瘤活检标本。 进展后，全外显子组和转录组测序将用于鉴定基因组 改变可能会导致阻力。总之，这项工作应该提供一个严格的分析阻力， MAPK抑制剂和克服它们的新治疗方法。

Mutation of the BRAF oncogene is a common event in colorectal cancer (CRC). These mutations are associated with adverse outcome and insensitivity to epidermal growth factor receptor (EGFR) based therapy. Whereas RAF inhibitors have been succesful in the treatment of BRAF-mutant malignant melanoma, response rates in BRAF-mutant CRC are surprisingly low. The basis for these disparate treatment outcomes remains incompletely understod. Preliminary studies from our groups found that suppression of the MAPK pathway by PLX4720 is incomplete in CRC lines. In some cases, this may be due to augmented EGFR-dependent signaling, but this does not explain all resistance in this setting. Our objective is to identify mechanisms operant in BRAF-mutant colorectal cancer that confer de novo resistance to RAF inhibitors, in hopes of enabling more efficacious therapeutics. First, differentially expressed genes linked to BRAF-mutant CRC will be identified by analysis of the TCGA dataset; these genes will be Integrated with those that modify response to MAPK pathway inhibitors based on ongoing systematic functional screens. Top-ranking genes will be subjected to mechanistic studies to elucidate the molecular basis by which they confer resistance, in parallel, ongoing functional screens will be expanded to Identify genes that are synthetic lethal with RAF inhibition in BRAF-mutant colorectal cells. Here, validation of leading candidates will be prioritized for genes that are potentially druggable-several candidates have already been nominated. Rational combinations of targeted agents with RAF inhibitors will be explored in cell culture and in xenograft models. Finally, clinical trials of combined RAF and MEK inhibitors will be performed at DF/HCC in an attempt to improve efficacy by enhancing suppression of the MAPK pathway and possibly prevent the emergence of drug-resistance. Tumor biopsies will be collected pre-treatment, on-treatment and post-progression, and whole exome and transcriptome sequencing will be used to identify genomic alterations that may drive resistance. Altogether, this work should provide a rigorous analysis of resistance to MAPK inhibitors and new therapeutic approaches to overcome them.