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

项目摘要 恶性周围神经鞘瘤（MPNSTs）代表了一组高度侵袭性的软组织 肉瘤发生在不同的临床环境中：神经纤维瘤病1（NF 1）相关（45%），散发（45%）或 放疗（RT）相关（10%）。MPNST转移较早，对放疗和全身性治疗有抵抗力 化疗，预后差。无论临床情况如何，MPNST都具有相同的分子生物学特征。 NF 1途径失活（> 90%，因此NF 1缺陷），多梳抑制复合物2（PRC 2），和 CDKN2A通过双等位基因遗传改变，表明它们可以类似地被分子靶向。NF1- 缺乏丛状神经纤维瘤对MEK抑制剂（MEKi）治疗临床反应良好;然而，NF 1- 由丛状神经纤维瘤引起的MPNST缺陷对MEKi普遍耐药，这表明 在更具侵袭性的外周神经鞘肿瘤中，使用MPNST患者肿瘤样品 和临床前MPNST模型，我们已经发现PRC2缺失导致PDGRA上调; MEKi 治疗导致PDGFRB的反馈上调，而与PRC 2状态无关。的收敛性 PDGFR通路通过不同的机制激活，这为靶向肿瘤细胞的治疗提供了新的机会。 PDGFR途径克服MPNST中的MEKi抗性。新型PDGFRA/B抑制剂Ripretinib的联合用药 与MEKi的结合导致体外和体内MPNST的协同生长抑制。我们假设 PDGFRA/B通路激活代表了MEKi的中心抵抗机制，并且组合了 Ripretinib（泛PDGFRA/B抑制剂）和binimetinib靶向PDGFR和MAPK通路 MEKi可能是NF1缺陷型MPNST的有效治疗策略。 在这里，我们建议调查肿瘤的异质性和细胞可塑性参与肿瘤的演变， 使用明确的临床前研究，对比尼美替尼以及Ripretinib和比尼美替尼联合用药产生适应性耐药性 MPNST体外和体内模型系统和单细胞分析，包括单细胞RNA-seq（scRNA-seq） 和一种新颖的条形码系统。此外，我们建议CCR/NCI之间进行合作临床研究， (Drs. Widemann/Shern）和MSKCC（Dr. Chi）进行联合用药的概念验证I/II期研究 Ripretinib和binimetinib在NF1缺陷型MPNST患者中的疗效。在本试验中，我们将评估和优化 使用传统ERK评价Ripretinib/binimetinib联合治疗的MAPK通路抑制 磷酸化和新建立的定制Pea3家族ETS调节的MAPK信号。此外，我们将 还研究了肿瘤的异质性和细胞可塑性在肿瘤演变和耐药机制， 使用靶向NGS、scRNA-seq和整合分析的Ripretinib/binimetinib组合。该提案 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 产生治疗耐药性的机制见解，并提供关键的临床和翻译 为未来的确定性试验提供信息，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.