Cancer Cell Intrinsic Interferon-I pathway Activation by Fractionated Radiation

最近的证据表明，肿瘤中存在传统的树突状细胞1型(CDc1) 微环境(TME)是免疫检查点阻断(ICB)治疗反应所必需的。除了交叉- CD8+和CD4+T细胞呈递肿瘤细胞来源的抗原，cDC1通过效应T细胞促进肿瘤侵袭， 并支持它们的生存和功能。因此，改善cDC1招募到TME的干预措施可以增强 患者对ICB的反应。焦点放射治疗(RT)增加对ICB治疗的反应，至少部分是通过诱导 I型干扰素(干扰素-I)和驱动cDc1进入受照射的肿瘤。我们之前已经证明了cDc1是必不可少的 在治疗的小鼠中，免疫介导的辐射和同步非辐射肿瘤的消退(非局部性效应) RT和ICB。在接受RT和ICB治疗的转移性癌症患者中也取得了异常反应，但 可靠性低于预期，这种反应的决定因素仍不清楚。我们假设之前的一个 对异常反应的未知障碍是cDc1对免疫原性低的肿瘤的有限渗透，它 排除照射后肿瘤部位产生的效应性T细胞排斥非照射肿瘤。此外，我们 假设在受照射的肿瘤中激活强烈的干扰素-I反应对于实现全身性 激活自然杀伤(NK)细胞，这可能是非辐射肿瘤的归宿，并促进cDC1的招募。这 假设得到了强有力的科学前提的支持，这一前提是基于最近的文献和我们广泛的 已发表和未发表的数据，包括放射治疗后血清IFNb升高是非镜检的最高预测因素 转移性肺癌患者接受RT+抗CTLA4治疗的反应(NAT Med 2018)。为了检验这一假说，有三个 计划了独立但相关的目标，以解决不同的机械问题。目标1将调查这一角色 核糖核酸：DNA杂交物，聚集在受辐射的癌细胞的胞浆和小细胞外的货物中 它们在癌细胞和局部DC中通过cGAS/STIN激活干扰素-I途径而产生的囊泡(SEV)。角色 RT诱导的IFNb在全身NK细胞激活中的作用将通过使用IFNAR1缺陷的NK细胞来证实。目标2将 利用Rab27a缺失的癌细胞在体内确定SEV在RT诱导的干扰素-I激活中的作用。目标3将 直接阐述NK细胞在非局部性肿瘤中驱动cDC1侵袭的作用以及对RT+ICB的非局部性反应。在……里面 此外，对RT+抗-DNA有异常反应的肺癌患者外周血中存在NK细胞功能亚群。 CTLA4将通过单细胞分析进行研究。拟议的研究结果将确定一种新的机制， RT诱导局部干扰素-I激活NK细胞和CDC1之间的系统性串扰，这是T细胞介导所必需的 远端肿瘤的排斥反应。

Recent evidence indicates that the presence of conventional dendritic cells type 1 (cDC1) in the tumor microenvironment (TME) is required for response to immune checkpoint blockade (ICB) therapy. In addition to cross- presenting cancer cell-derived antigens to CD8+ and CD4+ T cells, cDC1 promote tumor infiltration by effector T cells, and support their survival and function. Thus, interventions that improve cDC1 recruitment to the TME could enhance patient responses to ICB. Focal radiation therapy (RT) increases responses to ICB therapy, at least in part by inducing type I interferon (IFN-I) and driving cDC1 into the irradiated tumor. We have previously shown that cDC1 are essential for immune-mediated regression of irradiated and synchronous non-irradiated tumors (abscopal effect) in mice treated with RT and ICB. Abscopal responses have also been achieved in metastatic cancer patients treated with RT and ICB, but less reliably than expected, and the determinants of such responses remain unclear. We hypothesize that a previously unexplored barrier to abscopal responses is the limited infiltration of poorly immunogenic tumors by cDC1, which precludes effector T cells generated at the irradiated tumor site from rejecting non-irradiated tumors. Moreover, we hypothesize that activation of a strong IFN-I response in the irradiated tumor is essential for achieving systemic activation of natural killer (NK) cells, which can home to non-irradiated tumors and foster the recruitment of cDC1. This hypothesis is supported by a strong scientific premise which is based on the recent literature and on our extensive published and unpublished data, including the fact that increased serum IFNb post-RT was the top predictor for abscopal responses in metastatic lung cancer patients treated with RT+anti-CTLA4 (Nat Med 2018). To test this hypothesis three independent but related aims that address different mechanistic questions are planned. Aim 1 will investigate the role of RNA:DNA hybrids, which accumulate in the cytosol of irradiated cancer cells and in the cargo of small extracellular vesicles (sEV) they produce, in activating the IFN-I pathway via cGAS/STING in cancer cells and locoregional DCs. The role of RT-induced IFNb in systemic NK cell activation will be confirmed by using IFNAR1-deficient NK cells. Aim 2 will determine the contribution of sEV to RT-induced IFN-I activation in vivo by using Rab27a-deficient cancer cells. Aim 3 will directly address the role of NK cells in driving cDC1 infiltration in abscopal tumors and abscopal responses to RT+ICB. In addition, NK cell functional subsets present in the blood of lung cancer patients with abscopal response to RT+anti- CTLA4 will be investigated by single cell analysis. Results of proposed studies will identify a novel mechanism whereby local IFN-I induction by RT activates a systemic cross-talk between NK cells and cDC1, required for T-cell mediated rejection of abscopal tumors.