Targeting exosomal PDL1 to improve immunotherapy

项目摘要-项目1 免疫检查点抑制物(ICI)，如抗PD-1抗体，已经为许多人的抗肿瘤治疗带来了革命性的变化 癌症类型，包括转移性黑色素瘤。然而，患者的应答率很低。组合在一起 治疗如ipilimumab和nivolumab产生较高的应答率，但与显着相关 毒物。一个尚未得到满足的主要需求是开发定量分析，对将对抗-HBs有反应的患者进行分层 PD-1治疗以避免不必要的毒性，并指导无反应者进行替代治疗。这样的前奏- 治疗或早期治疗预测指标将为临床医生提供决策支持信息，以优化 黑色素瘤患者的治疗。虽然双方学术界都有极大的兴趣和密集的努力 和行业识别对ICI的反应的预测因素，目前的生物标记物是次优的，并且处于早期- 治疗生物标记物不适用于任何癌症类型。外切小体是由 细胞转移到细胞外环境。我们发现，转移性黑色素瘤细胞分泌富含Pd-1的外切体。 L1，抑制循环中CD8T细胞的功能，促进肿瘤生长。在患者的血浆中， 循环胞外PD-L1水平及其在抗PD-1治疗过程中的变化 与患者对抗PD-1治疗的反应有关(Chen等人，《自然》2018年)。最近，我们发现 肿瘤相关巨噬细胞()也分泌携带PD-L1的外体(-Expd-L1)，这是一种 可以选择性地在患者血液中进行定量测量。外切体有效地抑制了 CD8T细胞的增殖和功能。项目1的总体目标是开发一种定量液体 基于活检的工具，使临床医生能够预测患者对基于ICI的治疗的反应，并 了解衍生的外切体在免疫抑制中的作用。在目标1中，我们将检验假设 EXPD-L1，尤其是-EXPD-L1，单独或联合使用是预测患者的有效因素 对ICI的反应。我们使用一个大型的多机构验证的患者样本集进行分析 不同的主要治疗背景，利用孢子提供的独特基础设施。在目标2中，我们 将系统地研究衍生的外切体在免疫抑制中的关键作用 黑色素瘤-巨噬细胞共培养系统、人源化小鼠系统和直接从 病人肿瘤组织。总之，我们的工作将建立外体PD-L1作为临床相关的理论基础 保证临床诊断学未来发展的分层。这项拟议的研究还将揭示 在免疫抑制方面的外显，这不仅会增进我们对免疫抑制的认识 在新的维度，但也有助于开发新的治疗方法，以改善患者的治疗 患有黑色素瘤。

Project Summary - Project 1 Immune checkpoint inhibitors (ICI) such as anti-PD-1 antibodies have revolutionized anti-tumor therapy for many types of cancers including metastatic melanoma. However, the patient response rates are low. Combined therapies such as ipilimumab and nivolumab produce a higher response rate but are associated with significant toxicities. A major unmet need is to develop quantitative assays that stratify patients who will respond to anti- PD-1 therapy to avoid unnecessary toxicities, and direct non-responders to alternative treatments. Such a pre- treatment or early on-treatment predictor would provide decision-enabling information to clinicians to optimize the treatment of melanoma patients. While there is enormous interest and intensive efforts from both academia and industry to identify predictors to response to ICI, the current biomarkers are suboptimal and early on- treatment biomarkers are not available for any cancer types. Exosomes are nano-sized vesicles secreted by cells to the extracellular milieu. We found that metastatic melanoma cells secrete exosomes enriched with PD- L1, which suppress the function of CD8+ T cells in circulation and facilitate tumor growth. In patients’ plasma, the level of circulating exosomal PD-L1 (“exPD-L1”) and its change during the course of anti-PD-1 treatment are associated with the patient response to anti-PD-1 therapy (Chen et al., Nature 2018). Most recently, we found that tumor associated macrophages (TAM) also secrete exosomes that carry PD-L1 (“TAM-exPD-L1”), which can be selectively and quantitatively measured in patient blood. TAM exosomes effectively suppress the proliferation and function of CD8 T cells. The overarching goals of Project 1 are to develop a quantitative liquid biopsy-based tool that enables clinicians to predict the patient response to ICI-based therapies, and to understand the role of TAM-derived exosomes in immune suppression. In Aim 1, we will test the hypothesis that exPD-L1, and especially TAM-exPD-L1, individually or in combination, are effective predictors of patient response to ICI. We perform the assays using a large multi-institutional validation set of patient samples across different major therapeutic contexts, taking advantage of the unique infrastructure SPORE offers. In Aim 2, we will systematically investigate the pivotal roles of TAM-derived exosomes in immune suppression using melanoma-macrophage co-culture system, humanized mouse system, and exosomes purified directly from patient tumor tissues. Together, our work will establish exosomal PD-L1 as a rationale-based clinically relevant stratifier that warrants future development for clinical diagnostics. The proposed study will also unveil a role of TAM exosomes in immune suppression, which will not only advance our understanding of immune suppression at new dimensions, but also helps develop novel therapeutic approaches to improve the treatment of patients with melanoma.