Intratumoral plasma cells in MPNST response to CDK4/6 targeted therapy and sensitization to immune checkpoint blockade

项目摘要/摘要 恶性周围神经鞘瘤(MPSNTs)是一种致命的、基本上无法治愈的肉瘤 有效的治疗方法。驱动MPNSTs的标志性变化是NF1突变，导致RAS-MEK激活， 和CDKN2A的丢失，导致CDK4/6的过度激活。我们的实验室发现，MEK和CDK6的双重抑制 CDK4/6(由于两种药物均下调CDK4/6的表达，故简称CDK4/6靶向治疗)具有协同作用 在具有免疫能力的小鼠中显著缩小从头开始的MPNSTs。肿瘤消退与一种 肿瘤内浆细胞(IPC)增加，这在赋形剂控制和耐药性中没有观察到 肿瘤。IPC预后更好的总体存活率，增加第三级淋巴结构(TLS)的形成 包含激活的CD8+T细胞，并改善了对免疫检查点阻断(ICB)治疗的反应 许多人类癌症，包括其他肉瘤。我发现CDK4/6靶向治疗使从头开始敏感 利用PD-L1抗体结合实现MPNSTs对ICB的作用 对10%的小鼠有明显的治愈作用。这些发现支持我的中心假设，即CDK4/6靶向治疗 通过浆细胞依赖调节导致肿瘤消退和对ICB治疗的增强反应 肿瘤浸润性免疫细胞。这将通过两个相辅相成的目标来检验： 目的1：明确靶向CDK4/6引起MPNSTs免疫成分改变与IPC的关系 使用或不使用抗PDL1治疗。 目的2：探讨IPC在CDK4/6诱导MPNST免疫应答中的作用机制及意义 靶向和/或抗PDL1治疗。 拟议的研究采用了一个已建立的从头开始MPNST的模型，该模型由CRISPR编辑 NF1+CDKN2a在免疫能力强的小鼠中，与人类疾病非常相似。免疫功能的变化 治疗后MPNSTs的组成将通过组织病理学，流式细胞仪， 细胞因子/趋化因子阵列和转录组分析及结果与该药的抗肿瘤疗效相关 治疗。通过这些目标，我将阐明治疗引起的内皮祖细胞和其他肿瘤浸润性改变。 并确定浆细胞丢失是否会降低CDK4/6靶向和/或ICB的抗肿瘤效果 心理治疗。这样的实验将第一次在任何类型的肿瘤中确立治疗的意义- 诱导免疫球蛋白在抗肿瘤免疫反应中的作用。IPC在增强蛋白激酶抑制物和ICB中的作用 疗法越来越受到人们的关注，但到目前为止仍未得到检验；它将在MPNST的背景下定义。 这些发现可能会指导MPNSTs的新治疗，包括涉及ICB试剂的免疫疗法，并已 广泛适用于其他癌症。

Project Summary / Abstract Malignant peripheral nerve sheath tumors (MPSNTs) are deadly, essentially incurable sarcomas that lack effective therapies. Hallmark alterations driving MPNSTs are NF1 mutation, leading to Ras-MEK activation, and loss of CDKN2A, leading to hyperactivation of CDK4/6. Our lab found that dual inhibition of MEK and CDK4/6 (simplified as ‘CDK4/6 targeted therapy’ since both drugs downregulate CDK4/6) acts synergistically to dramatically shrink de novo MPNSTs in immune competent mice. Tumor regression coincides with an increase in intratumoral plasma cells (IPCs), which was not observed in vehicle control and drug-resistant tumors. IPCs prognose better overall survival, increased formation of tertiary lymphoid structures (TLS) containing activated CD8+ T cells, and improved response to immune checkpoint blockade (ICB) therapies in many human cancers, including other sarcomas. I found that CDK4/6 targeted therapy sensitizes de novo MPNSTs to ICB using Programmed Death Ligand 1 (PD-L1) antibodies with the combination achieving apparent cure in 10% of mice. These findings support my central hypothesis that CDK4/6 targeted therapy causes tumor regression and enhanced response to ICB therapy through a plasma-cell dependent modulation of tumor infiltrating immune cells. This will be tested through two complementary aims: Aim 1: Define IPC associations with immune composition changes in MPNSTs caused by CDK4/6 targeted therapy with or without anti-PDL1 therapy. Aim 2: Determine the mechanism and significance of IPCs in the MPNST immune response to CDK4/6 targeted and/or anti-PDL1 therapy. Proposed studies employ an established model of de novo MPNSTs generated by CRISPR editing of Nf1+Cdkn2a in immune competent mice, closely mimicking the human disease. Changes in the immune composition of MPNSTs following therapy will be determined through histopathological, flow cytometric, cytokine/chemokine arrays and transcriptome analyses and results correlated with the antitumor efficacy of the therapies. Through these aims, I will elucidate therapy-induced changes in IPCs and other tumor infiltrating immune cells and determine if plasma cell loss reduces the antitumor efficacy of CDK4/6 targeted and/or ICB therapy. Such experiments will, for the first time in any tumor type, establish the significance of therapy- induced IPCs in the antitumor immune response. The role of IPCs in potentiating kinase inhibitor and ICB therapies is of growing interest but so far remains untested; it will be defined here in the setting of MPNSTs. Findings may guide new treatments for MPNSTs, including immunotherapy involving ICB agents, and have broad applicability to other cancers.