Metronomic Radiotherapy Reverses Tumor Immune Desertification and Resistance to Immunotherapy. Metronomic Radiotherapy Reverses Tumor Immune Desertification and Resistance to Immunotherapy

The development of approaches for inflaming cold tumors is critical for increasing response to immunotherapy (IMT) reliant upon the re-invigoration of T cells for tumor control. Here we report, in a pre-clinical advanced ID8 ovarian cancer model, that metronomic low-dose radiotherapy (LDRT; 1 Gy) promotes T-cell infiltration and enables responsiveness to treatment including low-dose cyclophosphamide (CP), and combinatorial IMT comprising immune checkpoint blockade (ICB) targeting PD-1 and CTLA-4, and anti-CD40 agonist antibody, for significant tumor control and survival. Responses to this radio-combinatorial immunotherapy (RACIM) relied upon re-programming of both innate and adaptive immunity. We further identified RACIM-induced intratumoral dendritic cell states with co-stimulatory capacity and expressing the stress ligand RAE1, as well as of polyfunctional NKG2D+TCF1-PD1+CD4+T cells. We further report major tumor regressions in a subset of advanced cancer patients for which cold tumors were treated with LDRT, CP, aspirin, and ICB (NCT03728179). Unbiased analyses of biopsies revealed T-cell infiltration, up-regulation of type I IFN, and Th1 signatures as well as down-regulation of M2 macrophage and epithelial to mesenchymal transition gene-signatures, and a more oligoclonal TCR repertoire after RACIM, in responding patients. Overall design: Evaluation of the impact on immune cells of low dose whole abdominal radiotherapy in orthotopic ovarian cancer. In this experiments, mice were injected ID8 ovarian cancer cells (5 million). 21 days later mice were treated: 1) control/NT, cyclophophamide(CP)+ aPD1+aCTLA4+aCD40ag (IT), or CP + IT + low-dose Rx (1 gray each) 8 days later, a second round. 5 days later mice were sacrificed and tumors processed.

激活冷肿瘤的相关策略开发，对于提升依赖T细胞复壮以实现肿瘤管控的免疫治疗（immunotherapy, IMT）响应率至关重要。本研究在临床前高级别ID8卵巢癌模型中发现，节律性低剂量放疗（metronomic low-dose radiotherapy, LDRT；1 Gy）可促进T细胞浸润，并使多种治疗方案产生响应：包括低剂量环磷酰胺（cyclophosphamide, CP），以及联合免疫治疗方案——靶向PD-1与CTLA-4的免疫检查点阻断（immune checkpoint blockade, ICB）联合抗CD40激动剂抗体，最终实现显著的肿瘤管控与生存获益。该放射联合免疫治疗（radio-combinatorial immunotherapy, RACIM）的响应效果依赖于固有免疫与适应性免疫的重编程。本研究进一步鉴定出RACIM诱导的两类瘤内免疫细胞亚群：具备共刺激能力且表达应激配体RAE1的树突状细胞，以及多功能NKG2D+TCF1-PD1+CD4+T细胞。我们还报道了一组晚期癌症患者的显著肿瘤消退案例：该队列中冷肿瘤患者接受了LDRT、CP、阿司匹林联合ICB治疗（临床试验编号NCT03728179）。对活检样本的无偏分析显示，在产生响应的患者中，RACIM治疗后可观察到T细胞浸润增加、I型干扰素与Th1特征基因上调，同时M2型巨噬细胞与上皮间质转化相关基因特征下调，且T细胞受体（TCR）库呈现寡克隆化特征。实验整体设计：评估全腹低剂量放疗对原位卵巢癌模型免疫细胞的影响。本实验中，小鼠被接种500万个ID8卵巢癌细胞；21天后对小鼠进行如下处理：1) 对照组（NT，未处理组）；2) 环磷酰胺（CP）联合抗PD-1、抗CTLA-4、抗CD40激动剂（IT组）；3) CP联合上述免疫治疗方案，并于8天后给予第二轮低剂量放疗（每次1 Gy）。处理后第5天处死小鼠并获取肿瘤组织进行后续分析。