Understanding and targeting MAPK pathway activation in NF1-deficient malignant peripheral nerve sheath tumor (MPNST)

项目摘要 摘要恶性周围神经鞘瘤是一组高度侵袭性的软组织。 发生在不同临床环境中的肉瘤：神经纤维瘤病1(NF1)相关(45%)，散发性(45%)或 放射治疗(RT)相关(10%)。MPNSTs转移较早，对放疗和全身耐药 化疗效果差，预后差。无论临床环境如何，MPNST共享相同的分子 NF1(90%，因此NF1缺乏)、多梳抑制复合体2(PRC2)的通路失活，以及 CDKN2A通过双等位基因改变，表明它们可以类似的分子靶向。NF1- 临床上，缺陷性丛状神经纤维瘤对MEK抑制剂(Meki)治疗反应良好；然而，NF1- 丛状神经纤维瘤产生的缺陷MPNSTs普遍对Meki耐药，提示是内在的 更具侵袭性的外周神经鞘肿瘤中存在耐药性。应用MPNST患者肿瘤标本 和临床前MPNST模型，我们发现PRC2缺失导致PDGRA上调；Meki 治疗导致PDGFRb的反馈上调，与PRC2状态无关。的汇聚点 不同机制激活的PDGFR通路为靶向治疗提供了新的机会 PDGFR途径克服MPNST对Meki耐药。新型PDGFRA/B抑制剂利普替尼的联合应用 在体内外均能协同抑制MPNST的生长。我们假设 PDGFRA/B通路激活代表对Meki的中枢耐药机制 利普替尼(PAN-PDGFRA/B抑制剂)和比美替尼靶向PDGFR和MAPK通路 (Meki)可能为NF1缺陷的MPNST提供一种有效的治疗策略。 在这里，我们建议研究肿瘤的异质性和细胞可塑性与肿瘤的进化和 使用明确的临床前研究，对比尼美替尼的适应性耐药以及利培替尼和比尼美替尼的联合使用 体内外模型系统和单细胞分析，包括单细胞rna-seq(scrna-seq) 和一种新的条形码系统。此外，我们建议CCR/NCI之间进行一项合作的临床研究 (Widemann/Shern博士)和MSKCC(池博士)对这一组合进行概念验证阶段I/II研究 利培替尼和比美替尼在NF1缺陷MPNST患者中的应用。在这次试验中，我们将评估和优化 应用传统ERK评价利培尼/比尼美替尼联合治疗对MAPK通路的抑制作用 磷酸化和新建立的定制的Pea3家族ETS调节的MAPK信号。此外，我们还将 探讨肿瘤异质性和细胞可塑性在肿瘤演变中的作用及耐药机制。 利培替尼/比尼美替尼联合应用靶向NGS、scRNA-seq和综合分析。这项建议 利用MSKCC和CCR/NCI的协同专业知识和资源。我们相信，这些研究将 产生对治疗耐药性的机械性洞察，并提供关键的临床和翻译 未来最终试验的信息，有可能改变MPNST的临床实践。

Project Abstract Malignant peripheral nerve sheath tumors (MPNSTs) represent a group of highly aggressive soft tissue sarcomas that occur in distinct clinical settings: neurofibromatosis 1 (NF1)-associated (45%), sporadic (45%) or radiotherapy (RT)-associated (10%). MPNSTs metastasize early and are resistant to radiotherapy and systemic chemotherapy and have poor prognosis. Irrespective of the clinical settings, MPNSTs share the same molecular pathway inactivation in NF1 (>90%, hence NF1-deficient), Polycomb repressive complex 2 (PRC2), and CDKN2A through biallelic genetic alterations, suggesting that they can be molecularly targeted similarly. NF1- deficient plexiform neurofibroma responds well to MEK inhibitor (MEKi) treatment clinically; however, NF1- deficeint MPNSTs arising from plexiform neurofibromas are universally resistant to MEKi, suggesting intrinsic resistance in the more aggressive form of peripheral nerve sheath tumors. Using MPNST patient tumor samples and preclinical MPNST models, we have uncovered that PRC2-loss leads to PDGRA upregulation; MEKi treatment resulted in feedback upregulation of PDGFRB irrespective of the PRC2 status. The convergence of the PDGFR pathway activation by different mechanisms points to a novel therapeutic opportunity to target the PDGFR pathway to overcome MEKi resistance in MPNST. Combination of a novel PDGFRA/B inhibitor, ripretinib with a MEKi leads to synergistic growth inhibition of MPNST in vitro and in vivo. We hypothesize that PDGFRA/B pathway activation represent a central resistance mechanism to MEKi and combined targeting of the PDGFR and MAPK pathways with ripretinib (pan-PDGFRA/B inhibitor) and binimetinib (MEKi) may present an effective therapeutic strategy in NF1-deficient MPNST. Here, we propose to investigate the tumor heterogeneity and cellular plasticity involved in tumor evolution and adaptive resistance to binimetinib and combination of ripretinib and binimetinib, using well-defined preclinical MPNST in vitro and in vivo model systems and single-cell analysis including single cell RNA-seq (scRNA-seq) and a novel barcoding system. Additionally, we propose a collaborative clinical investigation between CCR/NCI (Drs. Widemann/Shern) and MSKCC (Dr. Chi) to conduct a proof-of-concept phase I/II study of the combination of ripretinib and binimetinib in patients with NF1-deficient MPNST. In this trial, we will assess and optimize the evaluation of MAPK pathway inhibition to the ripretinib/binimetinib combination therapy using traditional ERK phosphorylation and newly established custom Pea3-family ETS-regulated MAPK signature. Further, we will also investigate the tumor heterogeneity and cellular plasticity in tumor evolution and resistance mechanisms to the ripretinib/binimetinib combination using targeted NGS, scRNA-seq and integrative analysis. The proposal leverages the synergistic expertise and resources at MSKCC and CCR/NCI. We believe that these studies will generate mechanistic insight of therapeutic resistance and provide the pivotal clinical and translational information for future definitive trials, with the potential to change the clinical practice in MPNST.