Department of Neurosurgery, Washington University in St Louis School of Medicine, St Louis, Missouri, USA.
Department of Medicine, Division of Medical Oncology, Washington University in St Louis School of Medicine, St Louis, Missouri, USA.
J Immunother Cancer. 2022 Dec;10(12). doi: 10.1136/jitc-2022-005293.
Glioblastoma is a fatal disease despite aggressive multimodal therapy. PD-1 blockade, a therapy that reinvigorates hypofunctional exhausted CD8 T cells (T) in many malignancies, has not shown efficacy in glioblastoma. Loss of CD4 T cells can lead to an exhausted CD8 T-cell phenotype, and terminally exhausted CD8 T cells (T ) do not respond to PD-1 blockade. GL261 and CT2A are complementary orthotopic models of glioblastoma. GL261 has a functional CD4 T-cell compartment and is responsive to PD-1 blockade; notably, CD4 depletion abrogates this survival benefit. CT2A is composed of dysfunctional CD4 T cells and is PD-1 blockade unresponsive. We leverage these models to understand the impact of CD4 T cells on CD8 T-cell exhaustion and PD-1 blockade sensitivity in glioblastoma.
Single-cell RNA sequencing was performed on flow sorted tumor-infiltrating lymphocytes from female C57/BL6 mice implanted with each model, with and without PD-1 blockade therapy. CD8 and CD4 T cells were identified and separately analyzed. Survival analyses were performed comparing PD-1 blockade therapy, CD40 agonist or combinatorial therapy.
The CD8 T-cell compartment of the models is composed of heterogenous CD8 T subsets, including progenitor exhausted CD8 T cells (T ), intermediate T, proliferating T, and T . GL261 is enriched with the PD-1 responsive T subset relative to the CT2A and CD4-depleted GL261 models, which are composed predominantly of the PD-1 blockade refractory T subset. Analysis of the CD4 T-cell compartments revealed that the CT2A microenvironment is enriched with a suppressive T subset and an effector CD4 T-cell subset that expresses an inhibitory interferon-stimulated () signature. Finally, we demonstrate that addition of CD40 agonist to PD-1 blockade therapy improves survival in CT2A tumor-bearing mice.
Here, we describe that dysfunctional CD4 T cells are associated with terminal CD8 T-cell exhaustion, suggesting CD4 T cells impact PD-1 blockade efficacy by controlling the severity of exhaustion. Given that CD4 lymphopenia is frequently observed in patients with glioblastoma, this may represent a basis for resistance to PD-1 blockade. We demonstrate that CD40 agonism may circumvent a dysfunctional CD4 compartment to improve PD-1 blockade responsiveness, supporting a novel synergistic immunotherapeutic approach.
尽管采用了积极的多模式治疗，胶质母细胞瘤仍然是一种致命的疾病。PD-1 阻断疗法可使许多恶性肿瘤中功能低下的耗竭 CD8 T 细胞（T 细胞）重新焕发活力，但在胶质母细胞瘤中并未显示出疗效。CD4 T 细胞的缺失可导致耗竭的 CD8 T 细胞表型，而终末期耗竭的 CD8 T 细胞（T 细胞）对 PD-1 阻断无反应。GL261 和 CT2A 是胶质母细胞瘤的互补原位模型。GL261 具有功能性 CD4 T 细胞区室，对 PD-1 阻断有反应；值得注意的是，CD4 耗竭会消除这种生存获益。CT2A 由功能失调的 CD4 T 细胞组成，对 PD-1 阻断无反应。我们利用这些模型来了解 CD4 T 细胞对胶质母细胞瘤中 CD8 T 细胞耗竭和 PD-1 阻断敏感性的影响。
对植入每种模型的雌性 C57/BL6 小鼠的肿瘤浸润淋巴细胞进行单细胞 RNA 测序，并进行 PD-1 阻断治疗。鉴定 CD8 和 CD4 T 细胞，并分别进行分析。进行生存分析比较 PD-1 阻断治疗、CD40 激动剂或联合治疗。
模型的 CD8 T 细胞区室由异质性 CD8 T 细胞亚群组成，包括祖细胞耗竭的 CD8 T 细胞（T 细胞）、中间 T 细胞、增殖 T 细胞和 T 细胞。与 CD4 耗竭的 GL261 模型相比，GL261 富含 PD-1 反应性 T 细胞亚群，而 CT2A 则主要由 PD-1 阻断难治性 T 细胞亚群组成。对 CD4 T 细胞区室的分析表明，CT2A 微环境富含抑制性 T 细胞亚群和表达抑制性干扰素刺激基因（）特征的效应 CD4 T 细胞亚群。最后，我们证明，在 CT2A 荷瘤小鼠中添加 CD40 激动剂可改善生存。
在这里，我们描述了功能失调的 CD4 T 细胞与终末期 CD8 T 细胞耗竭有关，这表明 CD4 T 细胞通过控制耗竭的严重程度来影响 PD-1 阻断的疗效。鉴于 CD4 淋巴细胞减少症在胶质母细胞瘤患者中经常观察到，这可能是对 PD-1 阻断产生耐药性的基础。我们证明 CD40 激动剂可能绕过功能失调的 CD4 区室以改善 PD-1 阻断的反应性，支持一种新的协同免疫治疗方法。
