Targeting T cell dysfunction in glioblastoma: A proof-of-concept Phase 0/I trial of anti-TIGIT antibody AB154 in combination with anti-PD1 antibody AB122

摘要 胶质母细胞瘤（GBM）是成人中最常见的原发性脑肿瘤，预后不良， 尽管积极的管理，但生存期短。T细胞功能障碍是一个重要组成部分， 在GBM肿瘤微环境中观察到免疫抑制状态，并且仍然是GBM肿瘤微环境的重要屏障。 开发成功的免疫疗法。最近的研究表明，调节免疫检查点 与其他癌症相反，抑制剂α-PD-1或α-CTLA-4在GBM中不提供显著的临床益处。 这些数据表明，多种共抑制受体参与GBM肿瘤微环境驱动 T细胞功能障碍。在研究人类炎症性疾病中的T细胞功能障碍时，我们首先确定了一个关键因素， TIGIT在T细胞上通过CD 155作为主要共抑制途径的参与的作用;然后，我们证明了TIGIT在CD 155上的作用。 TIGIT在维持TCL 4的功能稳定性中的作用，因为TIGIT信号传导阻止TCL 4的转化， 转化为促炎细胞此外，我们和其他人已经发现TIGIT及其配体CD 155高度表达于细胞内。 在GBM中表达。我们使用单细胞RNAseq的新的初步数据显示，在GBM肿瘤浸润中， T细胞，TIGIT表达最高水平的TIGIT。抗TIGIT疗法现在正在进入癌症的临床试验 最近，α-TIGIT mAb tiragolumab获得FDA突破性认定。在本提案中，我们将 通过进行α-TIGIT和α-PD的0/1期临床试验，阐明了GBM中T细胞功能障碍的机制。 1 mAb作为检查点抑制剂用于治疗复发性GBM。试验设计允许确定安全性 同时提供肿瘤样本和血液样本，用于人体内的稳健评估。 单独或组合的α-TIGIT和α-PD-1的作用，具有转录组单细胞分辨率。我们 一种机制假说是，虽然抗PD-1增强效应T细胞和调节T细胞增殖， 将α-TIGIT添加到α-PD-1将使Treg功能不稳定并优化免疫应答。探讨 在这一假设下，我们的试验采用了“机会之窗”设计，采用了实验室到床边到实验室的方法。 在切除复发性肿瘤的手术之前，患者将随机接受安慰剂或α-PD-1或α-PD-2。 TIGIT单独或组合。单细胞RNAseq（10 x）将在基线血液、 来自试验患者的治疗血液和肿瘤标本。我们将比较克隆性和功能性状， 肿瘤浸润性T细胞和效应T细胞，以及促炎性和抑制性肿瘤源性T细胞的频率。 骨髓细胞多重免疫荧光（4 i）将用于空间验证。我们将分析循环 与肿瘤浸润性T细胞克隆相关的T细胞，以识别外周相关性并开发非侵入性 新出现的免疫应答的生物标志物。然后，我们将模拟PD-1和TIGIT阻断对T淋巴细胞活化的影响。 使用健康供体T细胞进行体外试验，并与试验中观察到的效果进行比较。通过这一全面的 通过这种方法，我们的研究将确定PD-1和TIGIT受体是否参与GBM肿瘤中的T细胞 微环境诱导免疫功能障碍，不允许在该CNS肿瘤中进行免疫监测。

ABSTRACT Glioblastoma (GBM), the most common primary brain tumor in adults, is associated with a poor prognosis and short survival in spite of aggressive management. T cell dysfunction is a crucial component in the immunosuppressed state observed in the GBM tumor microenvironment and remains a significant barrier for the development of successful immunotherapies. Recent work suggests modulation with the immune-checkpoint inhibitors α-PD-1 or α-CTLA-4 do not provide significant clinical benefit in GBM, as opposed to other cancers. These data suggest that multiple co-inhibitory receptors are involved in the GBM tumor microenvironment driving T cell dysfunction. While investigating T cell dysfunction in human inflammatory disease, we first identified a key role for engagement of TIGIT on T cells by CD155 as a major co-inhibitory pathway; we then demonstrated a role for TIGIT in maintaining functional stability of Tregs, in that TIGIT signaling prevents conversion of Tregs into proinflammatory cells. Moreover, we and others have found that TIGIT and its ligand CD155 are highly expressed in GBM. Our new preliminary data using single-cell RNAseq shows that, among GBM tumor-infiltrating T cells, Tregs express the highest levels of TIGIT. Anti-TIGIT therapies are now entering clinical trials in cancer and recently, α-TIGIT mAb tiragolumab was given FDA breakthrough designation. In this proposal, we will elucidated mechanisms of T cell dysfuction in GBM by conducting a phase 0/1 clinical trial of α-TIGIT and α-PD- 1 mAbs as checkpoint inhibitors for treatment of recurrent GBM. The trial design allows for establishing the safety of this combination, while providing tumor samples and blood specimens for a robust evaluation of in human effects of α-TIGIT & α-PD-1 either alone or in combination, with transcriptomic single-cell resolution. Our mechanistic hypothesis is that while anti-PD-1 enhances both effector and regulatory T cell proliferation, the addition of α-TIGIT to α-PD-1 will destabilize Treg function and optimize the immune response. To investigate this hypothesis, our trial utilizes a “window-of-opportunity” design, within a bench-to-bedside-to-bench approach. Prior to surgery for resection of recurrent tumor, patients will be randomized to receive placebo, or α-PD-1, or α- TIGIT either alone or in combination. Single-cell RNAseq (10x) will be performed on baseline blood, post- treatment blood and tumor specimens from the trial patients. We will compare clonality and functional traits of tumor-infiltrating Tregs and effector T cells, and frequency of proinflammatory and suppressive tumor-derived myeloid cells. Multiplexed immunofluorescence (4i) will be used for spatial validation. We will analyze circulating T cells clonally related to tumor-infiltrating T cells to identify peripheral correlates and develop a non-invasive biomarker of emerging immune response. We will then model effects of PD-1 and TIGIT blockade on T regs in vitro using healthy donors T regs and compare to effects observed in the trial. Through this comprehensive approach, our study will determine whether PD-1 and TIGIT receptor engagement on T cells in the GBM tumor microenvironment induces immune dysfunction not allowing for immune survelliance in this CNS tumor.