基于预临床证据表明表观遗传学对免疫检查点抑制剂（ICI）的敏感性和耐药性有贡献，我们假设在对初始免疫检查点阻断治疗无效的转移性尿路上皮癌（UC）患者中，guadecitabine（低甲基化剂）和atezolizumab（抗-PD-L1）的联合治疗能够增强其临床疗效。我们设计了一项单臂Ⅱ期研究（NCT03179943），包括安全前期试验，以确定guadecitabine和atezolizumab联合治疗的建议Ⅱ期剂量。符合条件的患有复发/晚期尿路上皮癌，且之前使用PD-1或PD-L1靶向剂ICI治疗但疗效欠佳的患者参加该研究。预定的关联分析目的在于表征患者肿瘤的外周免疫动态、全局DNA甲基化、转录组和免疫浸润动态。安全前期试验招募了6名患者，Ⅱ期研究招募了15名患者，但由于无效而停止了试验。未观察到剂量限制性毒性。其中4名患者的病情得到控制（8-11个月）并存活（> 14个月），最佳反应为稳定病。关联分析表明，治疗后肿瘤中DNA去甲基化缺乏，但治疗后外周免疫激活和免疫浸润增加与无进展生存和稳定病相关。此外，患者血浆中的高IL-6和IL-8水平与短期生存相关。在该试验中，未观察到RECIST反应。虽然我们未能检测到guadecitabine预期的肿瘤内在效应，但低甲基化剂的添加却导致一些患者免疫激活，与长期生存相关。

Based on preclinical evidence of epigenetic contribution to sensitivity and resistance to immune checkpoint inhibitors (ICI), we hypothesized that guadecitabine (hypomethylating agent) and atezolizumab (anti-PD-L1) together would potentiate a clinical response in patients with metastatic urothelial carcinoma (UC) unresponsive to initial immune checkpoint blockade therapy.We designed a single arm Phase II study (NCT03179943) with a safety run-in to identify the recommended phase II dose of the combination therapy of guadecitabine and atezolizumab. Patients with recurrent/advanced urothelial carcinoma who had previously progressed on ICI therapy with PD-1 or PD-L1 targeting agents were eligible. Pre-planned correlative analysis was performed to characterize peripheral immune dynamics and global DNA methylation, transcriptome, and immune infiltration dynamics of patient tumors.Safety run-in enrolled 6 patients and Phase II enrolled 15 patients before the trial was closed for futility. No dose-limiting toxicity was observed. Four patients, with best response of stable disease, exhibited extended tumor control (8-11 months) and survival (>14 months). Correlative analysis revealed lack of DNA demethylation in tumors after 2 cycles of treatment. Increased peripheral immune activation and immune infiltration in tumors after treatment correlated with progression-free survival and stable disease. Furthermore, high IL-6 and IL-8 levels in the patients' plasma associates with short survival.No RECIST responses were observed after combination therapy in this trial. Although we could not detect the anticipated tumor-intrinsic effects of guadecitabine, the addition of hypomethylating agent to ICI therapy induced immune activation in a few patients, which associated with longer patient survival.