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: 9239071
• 负责人: Poulikos I Poulikakos
• 金额: $ 41.44万
• 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/9239071
• 关键词: Adverse drug effect; Adverse effects; Allosteric Regulation; Ally; Alpha Cell; 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; 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; 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; 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.

抽象的 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 维莫非尼和达拉非尼改善了患有 BRAF(V600E) 肿瘤的黑色素瘤患者的生存率。不幸- 通常，反应通常是暂时的，随后会产生抵抗，最常见的是由于无效 在药物存在的情况下抑制 RAF 并重新激活 ERK 信号传导。此外，RAF 抑制剂还可以 由于 RAF 和下游 ERK 信号传导的 RAS 依赖性矛盾激活，导致第二位点肿瘤 在正常细胞中。除黑色素瘤外，RAF 抑制剂对结直肠癌和甲状腺患者的疗效有限 BRAF(V600E)肿瘤，也是由于这些肿瘤中RAF/ERK信号传导的无效抑制所致。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更好的疗效， 但阻力最终也会出现。已确定 RAF/MEK 抑制剂组合的耐药机制 国家与 RAF 抑制剂单一疗法相似，表明对 RAF 抑制剂的抑制无效 英国皇家空军在这两种情况下都是一个关键的限制因素。因此迫切需要改进治疗策略 靶向致癌 BRAF 的药物，可以实现持久的反应和最小的副作用。我们的 先前的工作表明，二聚化对 BRAF 激酶的调节决定了重新 对目前使用的 RAF 抑制剂的耐药性和抑制剂诱导的 RAF 矛盾激活，但潜在的 机制仍不完全清楚。最近，具有不同结构的下一代 RAF 抑制剂 和生化特性已进入临床前和临床开发，但最合适的临床 它们的使用背景尚不清楚。该提案的目标是详细了解 控制小分子抑制剂靶向致癌 BRAF 的机制并利用该机制 知识，以便设计更有效的基于 RAF 抑制剂的治疗策略。更具体地说，我们 将 1) 通过连接来表征由于 BRAF 二聚化而对 RAF 抑制剂产生耐药性的机制基础 抑制剂与 BRAF 结合引起的构象变化对抑制剂的生化作用的影响，2) 详细了解细胞内抑制剂激活反常 RAF 的生化机制 与野生型 BRAF 和 3) 确定基于 RAF 抑制剂的二聚体肿瘤的有效治疗策略 BRAF 将克服 RAF 二聚体介导的对 RAF 抑制剂的内在或获得性耐药性。机甲- 通过所提出的实验获得的无常见解将能够合理设计更有效的小分子 ecule 抑制剂和 RAF 抑制剂为基础的治疗策略，针对致癌 BRAF 信号传导，具有微型 不良副作用和耐药时间延长。