Defining a cross-primed anti-tumor T cell signature to guide immunotherapy development

项目摘要/摘要 检查点封锁等免疫疗法使癌症治疗发生了革命性的变化，但人们只看到了反应 在一组患者中。尽管肿瘤的内在因素，如肿瘤突变负荷或干扰素γ“发炎” 签名部分预测了对检查点封锁的敏感性，这些相关性是有限的-大多数患者患有 “发炎”的肿瘤或高TMB仍然没有反应。T细胞介导的免疫疗法疗效的关键一步， 包括检查点阻断，是树突状细胞将肿瘤抗原(Ag)交叉递呈给CD8+T细胞。克罗斯- 在体内的呈现需要表达BATF3的1型树突状细胞(CDC1)，尽管这些树突状细胞有额外的 功能包括分泌T细胞募集趋化因子，驱动肿瘤反应性T细胞(TRT)反应。 由于富含cDc1的肿瘤患者对抗pd1抗体的反应有所改善，我们开发了一种原位 结合Flt3L、放射治疗(XRT)和TLR激动剂的疫苗接种(ISV)增强cDC1交叉启动 TRT，观察ISV增强PD1受体阻滞剂的抗肿瘤作用及诱导全身肿瘤的作用 接受治疗的患者的退化情况。此外，我们已经证明，过继转移肿瘤特异性T细胞到 同基因RAG-/-小鼠清除肿瘤，而转移到同种异基因RAG-/-小鼠无法控制肿瘤生长， 强调CD8+T细胞的APC交叉激发是抗肿瘤T细胞的有效性所必需的。尽管关键的是 CD8+T细胞对CD8+T细胞的交叉激发作用目前尚无成熟的T细胞测定方法 体内细胞交叉或直接启动。因此，迫切需要一种直接测量CD8+的方法 T细胞交叉引发寻找新的治疗靶点以增强交叉引发，并理解 治疗耐药的机制。我们假设交叉和直接免疫的T细胞，以及ISV免疫的VS 未经治疗的T细胞将具有不同的特征，反映出它们不同的抗肿瘤效果。在目标1中，我们将 利用H_2Kd基因敲除、H_2Kb转染法、GFP/OVA法建立小鼠交叉免疫和直接免疫小鼠模型 淋巴瘤和乳腺癌的表达及抗原特异性T细胞向同基因和异基因的转移 破烂不堪的老鼠。我们将对肿瘤反应性T细胞进行分类，并进行批量RNA-SEQ和光谱流式细胞术来鉴定 交叉启动的CD8+T细胞签名。在目标2中，我们将使用批量rna-seq和光谱流式细胞术来 描述T细胞对ISV的反应和跨肿瘤(淋巴瘤、乳腺癌)的检查点封锁， 模型抗原(GFP、OVA、荧光素酶)和内源性肿瘤抗原。这项研究的结果将是 交叉启动的CD8+T细胞表型的阐明和一种新的免疫监测技术 通过靶向新的检查点或共刺激分子来增加交叉免疫治疗的新免疫疗法的靶向设计 肿瘤反应性T细胞的启动。

PROJECT SUMMARY/ABSTRACT Immunotherapies such as checkpoint blockade have revolutionized cancer therapy, but responses are seen only in a subset of patients. Though tumor-intrinsic factors such as tumor mutational burden (TMB) or IFNγ “inflamed” signature partially predict sensitivity to checkpoint blockade, these correlations are limited—most patients with “inflamed” tumors or high TMB still fail to respond. A critical step for efficacy of T cell-mediated immunotherapies, including checkpoint blockade, is dendritic cell cross-presentation of tumor antigen (Ag) to CD8+ T cells. Cross- presentation in vivo requires Batf3-expressing type 1 dendritic cells (cDC1), though these DC have additional functions, including secretion of T cell-recruiting chemokines, driving tumor-reactive T cell (TRT) responses. Because patients with cDC1-enriched tumors have improved responses to anti-PD1, we developed an in situ vaccination (ISV) combining FLT3L, radiotherapy (XRT), and TLR agonism to enhance cDC1 cross-priming of TRT and observed that ISV potentiated anti-tumor effects of PD1 blockade and induced systemic tumor regressions in treated patients. Additionally, we have shown that adoptive transfer of tumor-specific T cells into syngeneic RAG-/- mice clears tumors, while transfer into allogeneic RAG-/- mice fails to control tumor growth, highlighting that APC cross-priming of CD8+ T cells is required for efficacy of antitumor T cells. Despite the critical role of cDC1 cross-priming of CD8+ T cells for effective therapy, there is no established method for measuring T cell cross- or direct-priming in vivo. Consequently, there is a critical need for methods to directly measure CD8+ T cell cross-priming for identifying novel therapeutic targets to enhance cross-priming, and to understand mechanisms of therapy resistance. We hypothesize that cross- and direct-primed T cells, and ISV-primed vs untreated T cells, will harbor distinct signatures, mirroring their differential antitumor efficacy. In Aim 1, we will develop mouse models of cross- and direct-priming using H2Kd knockout, H2Kb-transfected, GFP/OVA- expressing lymphoma and breast cancers and transfer of Ag-specific T cells into syngeneic and allogeneic RAG-/- mice. We will sort tumor-reactive T cells and perform bulk RNA-seq and spectral flow cytometry to identify a cross-primed CD8+ T cell signature. In Aim 2, we will use bulk RNA-seq and spectral flow cytometry to characterize the T cell response to ISV and checkpoint blockade across tumors (lymphoma, breast cancer), model antigens (GFP, OVA, luciferase), and endogenous tumor antigens. The outcome of this study will be elucidation of a cross-primed CD8+ T cell phenotype and a novel immune monitoring technique that allows targeted design of novel immunotherapies by targeting novel checkpoints or costimulators to increase cross- priming of tumor-reactive T cells.