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)是成人最常见的原发脑肿瘤，与预后不良和 尽管有激进的管理，但生存时间很短。T细胞功能障碍是导致T细胞功能障碍的重要因素 在GBM肿瘤微环境中观察到的免疫抑制状态，仍然是阻止 开发成功的免疫疗法。最近的研究表明，免疫检查点具有调节作用 与其他癌症不同，抑制剂α-PD-1或α-CTLA-4对基底细胞瘤没有显著的临床益处。 这些数据表明多种共抑制受体参与了GBM肿瘤微环境的驱动。 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 TIGIT通过CD155作为主要的共抑制途径在T细胞上的结合作用；然后我们展示了一个 TIGIT在维持Tregs功能稳定性中的作用，因为TIGIT信号阻止Tregs的转换 转化为促炎细胞。此外，我们和其他人发现，TIGIT及其配体CD155具有高度的 以GBM表示。我们使用单细胞RNAseq的新的初步数据显示，在浸润性的基底膜肿瘤中 T细胞、Tregs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单抗替拉戈卢单抗被FDA授予突破性称号。在这项提案中，我们将 通过α-TIGIT和α-PD-T的0/1期临床试验阐明基底膜T细胞功能障碍的机制 1单抗作为检查点抑制剂治疗复发的GBM。试验设计允许建立安全性 在提供肿瘤样本和血液样本的同时，对人类 α-TIGIT和α-PD-1单独或联合作用，具有转录切割单细胞分辨率。我们的 机制假说是，虽然抗PD-1促进了效应和调节性T细胞的增殖，但 将α-TIGIT加入到α-PD-1中会破坏Treg功能的稳定性，优化免疫应答。去调查 在这一假设下，我们的试验采用了“机会之窗”设计，即“床到床、床到床”的方法。 在手术切除复发肿瘤之前，患者将随机接受安慰剂或α-PD-1，或α- TIGIT可以单独使用，也可以组合使用。单细胞RNAseq(10倍)将在基线血液上进行，在- 治疗试验患者的血液和肿瘤标本。我们将比较克隆性和功能性特征 肿瘤浸润性T细胞和效应T细胞，以及促炎和抑制性肿瘤来源的频率 髓系细胞。多重免疫荧光(4I)将用于空间验证。我们将分析循环 克隆性相关T细胞与肿瘤浸润性T细胞识别外周相关性并发展成非侵袭性 新出现的免疫反应的生物标志物。然后我们将模拟PD-1和TIGIT封锁对T细胞的影响 体外使用健康供者T调节器，并与试验中观察到的效果进行比较。通过这个全面的 我们的研究将确定PD-1和TIGIT受体在GBM肿瘤中是否与T细胞结合 微环境导致免疫功能障碍，不允许这种中枢神经系统肿瘤的免疫存活。

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.