Dissecting the Gut Microbiota for Immune Checkpoint Blockade (ICB) - Resisting Microbes and Exploring the Generalizability of Microbiota-ICB Studies

项目总结 免疫检查点阻断(ICB)在10%-30%的人中产生了持久的肿瘤消退和稳定的疾病 患者患有一系列实体和血液系统恶性肿瘤。虽然它令人振奋的结果彻底改变了 在癌症治疗方面，要将ICBS的好处扩大到更多的癌症患者，还需要做很多工作。五花八门 研究强调了微生物区系对先天和获得性免疫的影响，以及它作为一种 可修改的目标，以提高ICB响应率。生态失调和肠道微生物多样性下降 与接受ICB的患者预后较差有关。在两项正在进行的临床试验中，粪便的初步结果 将ICB反应患者的微生物区系移植到ICB无反应患者展品中 恢复临床反应。此外，在小鼠和小鼠身上都发现了特定细菌的浓缩。 对检查站封锁做出反应的人类。微生物群和癌症之间的这种意想不到的联系持有 通过改变患者的微生物区系来加强癌症治疗的机会很有希望。虽然有一个 关于微生物区系-ICB相互作用的研究越来越多，微生物区系通过哪些机制 调节对癌症的免疫反应，癌症的治疗仍不清楚。为了更好地理解 微生物区系在免疫活性和ICB治疗中的贡献，我建立了一个抗ICB的灵知菌模型 PD-L1治疗黑色素瘤。我已经演示了和标准化的方法来评估定义的微生物 社区可以抑制B16黑色素瘤对抗PD-L1的反应，我已经开始对无反应者进行分级 社区，以识别和表征驱动反应失败的效应器物种。这笔赠款旨在 了解ICB-微生物区系相互作用在不同癌症类型和肿瘤中的稳健性 建立模型，鉴定和鉴定首批对抗PD-L1无反应的细菌，并探索 无反应的潜在机制。目标1-根据初步数据，我选择了两只SPF小鼠 微生物群和两个已定义的人类微生物群对抗癌药物的肿瘤生长反应率存在差异 PD-L1定植于无菌、B16黑色素瘤荷瘤小鼠。我的目标是了解它的健壮性和 通过探索肿瘤对微生物免疫治疗结果在肿瘤类型和ICBS中的普适性 检查点阻断治疗(抗PD-L1、抗PD-1和抗CTLA-4)后的生长差异。目标2- 根据之前的实验室发现，在基线条件下，无菌小鼠对抗PDL1有反应，我们预计 在每个非应答者群体中都存在一个或多个驱动非应答者群体的效应器物种 为抗PD-L1。为了战略性地阐明致病细菌菌株，我将对每个NR微生物区系进行分离 进入正交子社区，在无菌小鼠中定居，评估肿瘤生长趋势，并分析髓系 肿瘤和引流淋巴结中的T细胞群。通过研究这些灵知生物动物 ICB的不同临床反应，我们希望揭示减弱检查点封锁的效应器种类 响应，阐明机制，并确定修改微生物区系以改善癌症的新途径 结果。

PROJECT SUMMARY Immune checkpoint blockade (ICB) has yielded durable tumor regression and stabilized disease in 10-30% of patients for a range of solid and hematological malignancies. While its promising results have revolutionized cancer care, much work is needed to expand ICBs' benefit to a greater number of cancer patients. Various studies have highlighted the microbiota's impact on the innate and adaptive immunity and its potential role as a modifiable target to improve ICB response rates. Dysbiosis and decreased gut microbial diversity have been linked to poorer outcomes in patients receiving ICB. In two ongoing clinical trials, preliminary results of fecal microbiota transplantation of an ICB-responsive patient's microbiota into an ICB-non-responsive patient exhibit restored clinical response. Additionally, enrichment of specific bacteria has been identified in both mice and human that respond to checkpoint blockade. This unexpected link between the microbiome and cancer holds a promising opportunity to enhance cancer treatment by modifying the patient's microbiota. While there are a growing number of studies on microbiota-ICB interactions, mechanisms through which the microbiota modulates immune responses to cancer and cancer treatment remains unknown. To better understand the microbiota's contribution to immune activity and ICB treatment, I have established a gnotobiotic model of anti- PD-L1 treated melanoma. I have demonstrated and standardized methods to evaluate how a defined microbial community can inhibit B16 melanoma response to anti-PD-L1, and I have begun fractionating non-responder communities to identify and characterize effector species driving response failure. This grant aims to understand the robustness of ICB-microbiota interactions across different cancer types and tumor models, identify and characterize the first bacteria to drive non-response to anti-PD-L1 and explore potential mechanisms of non-response. Aim 1 – Based on preliminary data, I have selected two mice SPF microbiotas and two defined human microbiotas that exhibit contrasting tumor growth response rates to anti- PD-L1 when colonized into germfree, B16 melanoma-bearing mice. I aim to understand the robustness and generalizability of microbiome-immunotherapy findings across tumor types and ICBs by exploring tumor growth differences following checkpoint blockade therapy (anti-PD-L1, anti-PD-1, and anti-CTLA-4). Aim 2 – Based on previous lab findings that at baseline, germ free mice respond to anti-PDL1, we anticipate that there exists one or more effector species in each non-responder community that drives non-response to anti-PD-L1. To strategically elucidate the causative bacterial strains, I will fractionate each NR microbiota into orthogonal sub-communities, colonize germ-free mice, evaluate tumor growth trends, and analyze myeloid and T-cell populations in tumors and draining lymph nodes. By studying these gnotobiotic animals with different clinical responses to ICB, we hope to uncover the effector species that attenuate checkpoint blockade response, elucidate mechanisms, and identify novel avenues to modify the microbiota to improve cancer outcomes.