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

项目总结/摘要 KRAS中的致癌突变代表了肺腺癌中最常见的基因组驱动事件 （LUAD）（约30%），并在美国每年造成约25，000例死亡。 检查点抑制剂（ICI）在KRAS突变型非小细胞肺癌（NSCLC）中具有活性，但只有少数 的患者表现出持久的反应。共同发生的基因组改变可以塑造免疫生物学， KRAS突变型NSCLC并影响其对ICI的反应。RBM 10中的功能丧失体细胞突变，编码 选择性剪接（AS）的调节因子，在LUAD中普遍存在（~8%），并在KRAS中显著富集。 突变型NSCLC（约25%）。我们发现，KRAS突变型NSCLC肿瘤和细胞系中RBM 10的缺失导致 DNA双链断裂（DSB）和STING依赖性但cGAS非依赖性NF-κB信号传导， 免疫抑制性肿瘤微环境（TME）-富含MDSC和M2-巨噬细胞-并支持 肿瘤免疫逃逸重要的是，RD NSCLC对抗CSF 1 R表现出选择性敏感性，这取决于 功能性CD 8 + T细胞。初步证据表明，R环和不同STING同种型的积累， 支持RD细胞中DDR激活和优先NF-κB参与的候选机制。基于 我们的初步研究结果，我们假设：1。在KRAS突变型NSCLC中，RBM 10缺失触发R环 积累和异常的DDR信号，支持STING依赖性，但cGAS独立的亲， 致瘤性NF-κB信号传导; 2. RBM 10损失后的剪接失调促进STING同种型， 相对于TBK 1和IRF 3优先接合NF-κB; 3. RBM 10缺失重塑NSCLC TME并促进免疫 逃避4. RD NSCLC对ICI的敏感性可以通过共靶向STAT 3与TTI-101来增强。在目标1中， 我们将剖析RBM 10丢失、DDR激活和STING介导的NFκB信号传导之间的联系， 评估改变的R环稳态和替代STING剪接对这些表型的贡献。在 目的2，我们将全面表征的组成，信号通路和功能特性， 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 NSCLC临床标本中的关键发现。最后，在目标3中，我们将确定RBM 10失活的影响 使用入组两项III期临床试验的患者的临床结局数据/标本， durvalumab联合或不联合曲美木单抗与铂双联化疗的试验 未治疗的转移性NSCLC以及nivolumab/ipilimumab的3期临床试验。此外，我们将评估 共靶向STAT 3与抗PD-（L）1组合以增强免疫检查点的功效 RD-NSCLC中的阻断。临床意义：这项工作将研究剪接失调之间的新联系。 和由STING介导的免疫逃避，并将进一步寻求开发精确组合 RD NSCLC的免疫治疗方法。我们集合的多学科专家团队的力量 将有助于将发现快速转化为NSCLC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.