Dissecting and targeting mechanisms of genomic instability-triggered immune evasion in RBM10-deficient non-small cell lung cancer

项目摘要/摘要 KRAS癌基因突变是肺腺癌中最常见的基因组驱动事件 (LUAD)(~30%)，在美国每年约有25,000人死于免疫疗法(IO) 检查点抑制物(ICI)在KRAS突变型非小细胞肺癌(NSCLC)中是活性的，但只有少数 的患者表现出长期的反应。共同发生的基因组改变可以塑造人类免疫生物学 KRAS-突变体NSCLC并影响其对ICI的反应。RBM10的功能缺失体细胞突变，编码 选择性剪接调节因子(AS)，广泛存在于LUAD(~8%)中，并显著富含KRAS- 突变型NSCLC(~25%)。我们发现，在KRAS突变的NSCLC肿瘤和细胞系中，RBM10的缺失导致 DNA双链断裂(DSB)和依赖于刺痛但不依赖于cGAs的NF-κB信号，从而建立 富含MDSCs和M2-巨噬细胞的免疫抑制肿瘤微环境(TME)和支持 肿瘤免疫逃逸。重要的是，RD非小细胞肺癌对抗CSF1R表现出选择性敏感性，这取决于 功能性CD8+T细胞。初步证据表明，R环和不同的刺异构体积累为 在RD细胞中支持DDR激活和优先参与NF-κB的候选机制。基于 我们的初步发现我们假设：1.在KRAS突变体NSCLC中，RBM10丢失触发R环 积累和异常的DDR信号支持刺痛依赖但不依赖于cGAS的PRO 致肿瘤的NF-κB信号转导；2.RbM10缺失的剪接失调促进STIN型亚型 优先使用核因子-κB，而不是Tbk1和IRF3；3.RBM10缺失重塑非小细胞肺癌TME并增强免疫力 联合靶向STAT3和TTI-101可增强RD NSCLC对ICI的敏感性。在目标1中， 我们将剖析RBM10缺失、DDR激活和STING介导的NFκB信号之间的联系，我们将 评估改变的R环稳态和选择性刺痛剪接对这些表型的贡献。在……里面 目的2，我们将全面表征该蛋白的组成、信号通路和功能性质 临床前模型中的RD TME，以确定免疫逃避的关键介质，我们将验证 在非小细胞肺癌临床标本中的关键发现。最后，在目标3中，我们将确定RBM10失活的影响 利用两期3期临床患者的临床结果数据/样本研究ICI的临床疗效 杜伐单抗联合或不联合雷米诺单抗与铂类联合化疗的临床试验 未经治疗的转移性非小细胞肺癌以及nivolumab/ipilimumab的3期临床试验。此外，我们还将评估 共靶向STAT3联合抗PD-(L)1增强免疫检查点的作用 封锁在RD-NSCLC。临床意义：这项工作将检验剪接失调之间的新联系 以及以叮咬为媒介的免疫逃避，将进一步寻求开发精确的组合 RD非小细胞肺癌的免疫治疗途径。我们集结的多学科专家团队的实力 将促进将发现快速转化为非小细胞肺癌患者的临床进展。

Project Summary/Abstract Oncogenic mutations in KRAS represent the most prevalent genomic driver event in lung adenocarcinoma (LUAD) (~30%) and account for ~25,000 deaths annually in the U.S. Immunotherapy (IO) with immune checkpoint inhibitors (ICI) is active in KRAS-mutant non-small-cell lung cancer (NSCLC), however only a minority of patients exhibit long-lasting responses. Co-occurring genomic alterations can shape the immunobiology of KRAS-mutant NSCLC and impact its response to ICI. Loss-of-function somatic mutations in RBM10, encoding a regulator of alternative splicing (AS), are prevalent in LUAD (~8%) and are significantly enriched in KRAS- mutant NSCLC (~25%). We found that loss of RBM10 in KRAS-mutant NSCLC tumors and cell lines results in DNA double-strand breaks (DSBs) and STING-dependent but cGAS-independent NF-κB signaling, that establish an immunosuppressive tumor microenvironment (TME) – rich in MDSCs and M2-macrophages – and support tumor immune escape. Critically, RD NSCLC exhibit selective sensitivity to anti-CSF1R, that depends on functional CD8+ T-cells. Preliminary evidence points to accumulation of R-loops and distinct STING isoforms as candidate mechanisms that underpin DDR activation and preferential NF-κB engagement in RD cells. Based on our preliminary findings we hypothesize that: 1. In KRAS-mutant NSCLC, RBM10 loss triggers R-loop accumulation and aberrant DDR signaling that support STING-dependent but cGAS-independent pro- tumorigenic NF-κB signaling; 2. Splicing dysregulation upon RBM10 loss promotes STING isoforms that preferentially engage NF-κB over TBK1 and IRF3; 3. RBM10 loss remodels the NSCLC TME and fosters immune evasion 4. The sensitivity of RD NSCLC to ICI can be enhanced by co-targeting STAT3 with TTI-101. In Aim 1, we will dissect the link between RBM10 loss, DDR activation and STING-mediated NFκB signaling and we will assess the contribution of altered R-loop homeostasis and alternative STING splicing to these phenotypes. In Aim 2, we will comprehensively characterize the composition, signaling pathways and functional properties of the RD TME in preclinical models in order to identify critical mediators of immune evasion and we will validate key findings in NSCLC clinical specimens. Finally, in Aim 3, we will determine the impact of RBM10 inactivation on the clinical efficacy of ICI using clinical outcome data/specimens from patients enrolled in two phase 3 clinical trials of durvalumab with or without tremelimumab versus platinum-doublet chemotherapy for previously untreated metastatic NSCLC as well a phase 3 clinical trial of nivolumab/ipilimumab. In addition, we will evaluate co-targeting STAT3 in combination with anti-PD-(L)1 in order to enhance the efficacy of immune checkpoint blockade in RD-NSCLC. Clinical significance: This work will examine a novel link between splicing dysregulation and immune evasion that is mediated by STING and will further seek to develop precision combination immunotherapy approaches for RD NSCLC. The strength of our assembled multi-disciplinary team of experts will facilitate rapid translation of discoveries into clinical advances for NSCLC patients.