免疫检查点阻断（ICB）在肾细胞癌（RCC）患者中仅对少数患者显示持久的临床效益。我们旨在确定决定响应的分子特征，并发展增强响应的方法。我们研究了含SET结构域蛋白2（SEDT2）基因丧失对DNA损伤应答途径、细胞质DNA感应途径、肿瘤免疫微环境和RCC中ATR和检查点抑制的影响。ATR抑制激活环状GMP-AMP合酶（cGAS）-干扰素调节因子3（IRF3）-依赖性细胞质DNA感应途径，导致炎症细胞因子和免疫检查点的同时表达。在常见的RCC基因型中，SETD2丧失与ATR选择性激活相关，并使细胞对ATR抑制敏感。SETD2敲除在对ATR抑制的应答中促进了细胞质DNA感应途径。VE822 ATR抑制剂治疗同时上调Setd2敲除Renca肿瘤中的免疫细胞浸润和免疫检查点表达，为ATR抑制剂与ICB联合治疗提供了理论依据。Setd2缺失Renca肿瘤对ICB单一治疗或与VE822联合治疗比Setd2正常肿瘤表现出更大的脆弱性。此外，SETD2突变与接受ICB治疗的RCC患者中更高的响应率和延长的总生存期相关，但在未接受ICB治疗的RCC患者中则无相关性。SETD2丧失和ATR抑制协同促进cGAS信号传导和增强免疫细胞浸润，为具有SETD2突变的RCC患者中ATR和检查点抑制联合治疗提供了机制上的理论依据。

Immune checkpoint blockade (ICB) demonstrates durable clinical benefits in a minority of patients with renal cell carcinoma (RCC). We aimed to identify the molecular features that determine the response and develop approaches to enhance the response.We investigated the effects of SET domain-containing protein 2 (SEDT2) loss on the DNA damage response pathway, the cytosolic DNA sensing pathway, the tumor immune microenvironment, and the response to Ataxia telangiectasia and rad3 related (ATR) and checkpoint inhibition in RCC.ATR inhibition activated the cyclic GMP-AMP synthase (cGAS)-Interferon regulatory factor 3 (IRF3)-dependent cytosolic DNA-sensing pathway, resulting in the concurrent expression of inflammatory cytokines and immune checkpoints. Among the common RCC genotypes, SETD2 loss is associated with preferential ATR activation and sensitizes cells to ATR inhibition. SETD2 knockdown promoted the cytosolic DNA sensing pathway in response to ATR inhibition. Treatment with the ATR inhibitor VE822 concurrently upregulated immune cell infiltration and immune checkpoint expression in Setd2 knockdown Renca tumors, providing a rationale for ATR inhibition plus ICB combination therapy. Setd2 deficient Renca tumors demonstrated greater vulnerability to ICB monotherapy or combination therapy with VE822 than Setd2 proficient tumors. Moreover, SETD2 mutations were associated with a higher response rate and prolonged overall survival in ICB-treated RCC patients but not in non-ICB-treated RCC patients.SETD2 loss and ATR inhibition synergize to promote cGAS signaling and enhance immune cell infiltration, providing a mechanistic rationale for the combination of ATR and checkpoint inhibition in RCC patients with SETD2 mutations.