Mechanism-based strategies to target oncogenic BRAF signaling

针对致癌 BRAF 信号传导的基于机制的策略

• 批准号: 9899477
• 负责人: Poulikos I Poulikakos
• 金额: $ 13.56万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-12-08 至 2021-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9899477
• 关键词: Adverse drug effect; Allosteric Regulation; Ally; Area; BRAF gene; Binding; Biochemical; Biological Assay; Cell Line; Cells; Clinical; Colorectal; Complex; Data; Development; Dimerization; Drug Design; Drug resistance; Effectiveness; Event; Goals; Human; In complete remission; Investigation; Knowledge; Link; MEKs; Mediating; Modeling; Molecular Conformation; Multi-Drug Resistance; Mutate; Mutation; Normal Cell; Oncogenic; Outcome; Patients; Pharmaceutical Preparations; Pharmacology; Property; Proto-Oncogene Proteins B-raf; Protomer; Ras/Raf; Recovery; Regulation; Reporting; Resistance; Resistance development; Signal Transduction; Site; Structure; Testing; Therapeutic; Thyroid Gland; Time; Treatment Efficacy; Work; Xenograft procedure; acquired drug resistance; base; biophysical techniques; cell growth; clinical development; clinical efficacy; comparative efficacy; design; dimer; effective therapy; experimental study; improved; in vivo; inhibitor/antagonist; insight; melanoma; mutant; next generation; preclinical development; resistance mechanism; response; side effect; small molecule inhibitor; targeted treatment; tumor

Abstract BRAF kinase is frequently found mutated in human tumors and in the majority of melanomas. RAF inhibitors vemurafenib and dabrafenib improved survival of melanoma patients with BRAF(V600E) tumors. Unfortunate- ly, responses are usually temporary, followed by development of resistance, most commonly due to ineffective inhibition of RAF and reactivation of ERK signaling in the presence of the drug. In addition, RAF inhibitors in- duce second site tumors, due to RAS-dependent paradoxical activation of RAF and downstream ERK signaling in normal cells. Outside of melanoma, RAF inhibitors showed limited efficacy in patients colorectal and thyroid BRAF(V600E) tumors, also due to ineffective inhibition of RAF/ERK signaling in these tumors. More recently, combinations of RAF and MEK inhibitors showed improved efficacy compared to RAF inhibitor monotherapy, but resistance eventually emerges as well. Resistance mechanisms identified to the RAF/MEK inhibitor combi- nation are similar to the ones identified for RAF inhibitor monotherapy, suggesting that ineffective inhibition of RAF is a critical limiting factor in both contexts. There is thus a pressing need for improved therapeutic strate- gies targeting oncogenic BRAF, such that durable responses and minimal side effects can be achieved. Our previous work showed that regulation of BRAF kinase by dimerization determines both the development of re- sistance to currently used RAF inhibitors and inhibitor-induced RAF paradoxical activation, but the underlying mechanisms remain incompletely understood. Recently, next generation RAF inhibitors with different structural and biochemical properties have entered preclinical and clinical development, but the most appropriate clinical context for their use is unknown. The goal of this proposal is to accomplish a detailed understanding of the mechanisms governing the targeting of oncogenic BRAF by small molecules inhibitors and to use this knowledge in order to design more effective RAF inhibitor-based therapeutic strategies. More specifically, we will 1) characterize the mechanistic basis of resistance to RAF inhibitors due to BRAF dimerization by linking the conformational changes induced by inhibitor binding to BRAF to the biochemical effects of the inhibitor, 2) gain a detailed understanding of the biochemical mechanism of paradoxical RAF activation by inhibitors in cells with wild-type BRAF and 3) identify effective RAF inhibitor-based therapeutic strategies for tumors with dimeric BRAF that would overcome RAF dimer-mediated intrinsic or acquired resistance to RAF inhibitors. The mech- anistic insights gained by the proposed experiments will enable the rational design of more effective small mol- ecule inhibitors and RAF inhibitor-based therapeutic strategies targeting oncogenic BRAF signaling, with mini- mal side effects and prolonged time to resistance. !

摘要 BRAF激酶在人类肿瘤和大多数黑色素瘤中经常发现突变。RAF抑制剂 vemurafenib和dabrafenib改善了患有BRAF（V600 E）肿瘤的黑色素瘤患者的存活率。很不幸- 事实上，反应通常是暂时的，随后产生耐药性，最常见的是由于无效的 RAF的抑制和ERK信号转导的再激活。此外，RAF抑制剂在- 由于RAF和下游ERK信号传导的RAS依赖性反常激活， 在正常细胞中。在黑色素瘤之外，RAF抑制剂在结直肠和甲状腺癌患者中显示出有限的疗效。 BRAF（V600 E）肿瘤，也是由于这些肿瘤中RAF/ERK信号传导的无效抑制。最近， 与RAF抑制剂单一疗法相比，RAF和MEK抑制剂的组合显示出改善的功效， 但阻力最终也会出现。对RAF/MEK抑制剂组合的耐药机制鉴定 与RAF抑制剂单药治疗的结果相似，这表明RAF抑制剂的无效抑制 在这两种情况下，资源分配框架都是一个关键的限制因素。因此，迫切需要改进的治疗基质， 靶向致癌BRAF的疫苗，从而可以实现持久的反应和最小的副作用。我们 先前的工作表明，通过二聚化调节BRAF激酶决定了再形成和再分化的发展， 对目前使用的RAF抑制剂的耐受性和受体诱导的RAF反常激活，但潜在的 机制仍然不完全清楚。最近，具有不同结构的下一代RAF抑制剂， 和生化特性已经进入临床前和临床开发，但最合适的临床 其使用背景未知。本提案的目标是详细了解 通过小分子抑制剂控制致癌BRAF靶向的机制，并使用这种机制， 知识，以设计更有效的RAF通道为基础的治疗策略。更具体地说，我们 将1）表征由于BRAF二聚化而对RAF抑制剂产生抗性的机制基础， 抑制剂与BRAF结合诱导的构象变化与抑制剂的生物化学效应，2） 详细了解细胞中抑制剂对RAF反常激活的生化机制 和3）鉴定针对具有二聚体的肿瘤的有效的基于RAF靶点的治疗策略， BRAF将克服RAF二聚体介导的对RAF抑制剂的内在或获得性抗性。机甲- 所提出的实验获得的anistic见解将使更有效的小分子的合理设计， 靶向致癌BRAF信号传导的分子抑制剂和基于RAF通道的治疗策略， 严重的副作用和抵抗时间延长。 !