Mechanisms of PD-1 and Tim-3 crosstalk in tumor-infiltrating lymphocytes

项目总结 在过去的二十年里，免疫疗法在治疗许多类型的癌症方面发生了翻天覆地的变化- 基于检查点的方法，包括检查点封锁和过继细胞治疗，在一些国家产生了显著的效果 病人。到目前为止，无法在更多的患者中实现更完全的反应，这引发了广泛的 努力确定新的目标，以提高应答率和反应持续时间，无论是作为单一药物还是共同作用 第一代免疫疗法，如PD-1/PD-L1阻断。第二代检查站之一 包括我们自己在内的许多组织都注意到了TIM-3蛋白。到目前为止，单抗 靶向TIM-3在实体瘤的临床试验中表现不佳，可能部分原因是虽然 TIM-3在耗竭的T细胞上高水平表达，在TPEX细胞上不表达。获得更好的 了解TIM-3在这些不同细胞类型中的功能可能会导致更具选择性和有效性的TIM3- 靶向治疗，要么作为单一药物，要么关键是与PD-1途径阻断相结合。 我们小组和其他人的研究表明，TIM-3似乎对 肿瘤中大量存在的调节性T细胞(Treg)的抑制功能，特别是“效应器” Treg(ETreg)，这是Treg的一个特别抑制的子集。这些细胞在实体瘤中很丰富， 相对于它们在正常外周组织中的比例，这表明它们可能是更具吸引力的目标 肿瘤内免疫反应的特异性增强。因为有很大一部分Treg Express TIM- 3，并且该分子在体内的功能仍在阐明中，我们建立了一个基因敲除模型来研究TIM- 3在这些细胞上。因此，我们发现可诱导的Treg特异性TIM-3缺失导致 无论是同基因肿瘤的生长还是浸润性肿瘤的Treg数量。但是，Treg特定于 在动态平衡条件下，TIM-3缺失不会明显影响Treg的发育或免疫耐受。 根据已发表的和初步的数据，我们假设TIM-3是效应因子Treg的关键调节因子。 肿瘤微环境。我们将通过三个具体目标来检验这一假设。在目标1中，我们将确定 为什么在Treg特异性TIM-3KO小鼠的肿瘤中eTreg较少。在目标2中，我们将定义影响 Treg Tim-3的缺失对肿瘤微环境的影响。最后，在目标3中，我们将确定TIM-3的损失 在两种小鼠模型中，on Treg影响对PD-1检查点封锁的反应，扩展到 交互作用在头颈癌患者PD-1阻断治疗反应中的作用。 总之，这些研究将为将TIM-3作为治疗靶点进行更合理的翻译提供基础 实体瘤，在像PD-1这样的现有检查点靶点的背景下。因此，这些研究代表了一种合乎逻辑的 延长这一资助项目上一个周期开展的工作。

PROJECT SUMMARY The past twenty years have seen a sea change in the treatment of many types of cancer, with immunotherapy- based approaches, including checkpoint blockade and adoptive cell therapy, yielding remarkable results in some patients. The inability, thus far, to achieve more complete responses in more patients has set off a widespread effort to identify novel targets for improving rates and duration of response, either as single agents or together with first-generation immunotherapies, like PD-1/PD-L1 blockade. One of the second-generation checkpoint targets that has attracted attention from many groups, including our own, is the protein Tim-3. Thus far, mAb’s targeting Tim-3 have under-performed in clinical trials for solid tumors, likely due in part to the fact that while Tim-3 is expressed at high levels on exhausted T cells, it is not expressed on the TpEx cells. Obtaining a better understanding of Tim-3 function in these various cell types may lead to more selective and efficacious Tim3- targeting therapies, either as single agents or, critically, in combination with PD-1 pathway blockade. Work from our groups and others have revealed that Tim-3 appears to be particularly important for the suppressive function of regulatory T cells (Treg) that are present in high numbers in tumors, in particular “effector” Treg (eTreg), which are a particularly suppressive subset of Treg. These cells are enriched within solid tumors, relative to their proportions in normal peripheral tissues, suggesting that they could be attractive targets for more specific augmentation of immune responses within tumors. Since a significant proportion of Treg express Tim- 3, and the function of this molecule in vivo is still being elucidated, we generated a knockout model to study Tim- 3 on these cells. Thus, we found that inducible Treg-specific Tim-3 deletion results in a dramatic decrease in both the growth of syngeneic tumors and the number of Treg infiltrating those tumors. However, Treg-specific Tim-3 deletion did not detectably impact Treg development or immune tolerance under homeostatic conditions. Based on published and preliminary data, we hypothesize that Tim-3 is a critical regulator of effector Treg in the tumor microenvironment. We will test this hypothesis with three Specific Aims. In Aim 1, we will determine why there are fewer eTreg in the tumors of mice with Treg-specific Tim-3 KO. In Aim 2, we will define the effects of loss of Treg Tim-3 on the tumor microenvironment. Finally, in Aim 3, we will determine how the loss of Tim-3 on Treg impacts the response to PD-1 checkpoint blockade, in both mouse models, with an extension toward the role of the interaction in the response to PD-1 blockade therapy in patients with head and neck cancer. Together, these studies will provide the basis for more rational translation of Tim-3 as a target in the treatment of solid tumors, in the context of existing checkpoint targets like PD-1. As such, these studies represent a logical extension of work carried out in the previous cycle of this funded project.