Repurposing Glucosylceramide Synthase to Promote Mitochondrial Lethality and Potentiate an Anti-Tumor Immune Response in Triple-Negative Breast Cancer

项目概要 目前治疗三阴性乳腺癌（TNBC）的方法仍然不能令人满意。那里 建立新的替代疗法仍然是一个未满足的需求，这些疗法既可以对 癌细胞并刺激抗癌免疫反应，这可能提供额外的机会 与新兴的免疫疗法相结合。我们在 TNBC 中发现了一种新的肿瘤代谢特征 其中癌细胞利用鞘磷脂脂质清除表型，该表型可通过重新利用来靶向 选择性葡萄糖神经酰胺合酶抑制剂 Eliglustat，FDA 批准用于治疗戈谢病的药物 疾病。我们的初步研究表明，eliglustat 可促进有丝分裂毒性神经酰胺的积累 由此导致从存活线粒体自噬转变为致死性线粒体自噬以及随后的癌细胞死亡。此外，我们还展示了 eliglustat 在 TNBC 荷瘤小鼠中以临床可达到的剂量抑制肿瘤生长，并且 eliglustat 的抗癌作用与肿瘤浸润 CD4 和 CD8 的显着增加有关 T 细胞，表明 Eliglustat 在增强抗肿瘤免疫反应方面具有额外作用。初级 该提案的目标是建立 Eliglustat 作为“免疫代谢佐剂”的新用途 TNBC 的治疗并确定 Eliglustat 增强抗癌免疫的机制 回应。为了测试这一点，我们将评估 Eliglustat 在患者来源的异种移植物 (PDX) 中的抗癌功效 由初次接受过治疗的 TNBC 患者生成的模型，这些患者对治疗有或没有反应 化疗（具体目标 1a）。测试 eliglustat 联合抗 PD-L1 产量是否有所提高 与单独治疗相比，我们将使用 BRCA1co/co 的抗癌效果； MMTV-Cre； p53 /- 和 TNBC 4T1 原位同基因小鼠模型（具体目标 1b）。体内感兴趣的主要终点 研究将涉及总体生存率和肿瘤生长；干预后对肿瘤免疫表型的影响 将使用多重免疫荧光面板和单细胞转录组学进行单细胞水平的评估 组织的表达谱。我们还旨在确定 Eliglustat 诱导抗癌的机制 免疫反应。首先，我们将评估 Eliglustat 对 cGAS-STING 信号蛋白的影响， TNBC 细胞中的下游通路活性（具体目标 2a）。接下来，我们将使用先进的质谱仪 技术与细胞外囊泡 (EV) 的新颖分离方法相结合，以确定 MHC-I 结合 使用 Eliglustat 后，TNBC 细胞和 TNBC 衍生的循环和肿瘤内 EV 表面的肽组 治疗。 ELIspot 和基于细胞毒性 T 细胞的肿瘤杀伤活细胞测定将用于测试功能 EV 离体激活 T 细胞的作用（具体目标 2b）。如果成功，我们的潜在发现将提供关键的预 使用 Eliglustat 的临床证据以及将 Eliglustat 纳入早期临床试验的理由。 鉴于 Eliglustat 已获得 FDA 批准用于另一种适应症，因此它具有很高的转化潜力 进入临床应用，并有可能为癌症免疫治疗提供新的范例。

Project Summary Current approaches to treating triple-negative breast cancer (TNBC) remain unsatisfactory. There remains an unmet need to establish novel alternative therapies that can both exert targeted effects on cancer cells as well as stimulate an anti-cancer immune response that may render additional opportunity for combination with emerging immunotherapy. We have uncovered a novel onco-metabolic feature in TNBC wherein cancer cells exploit a sphingomyelin lipid scavenging phenotype that is targetable through repurposing of the selective glucosylceramide synthase inhibitor eliglustat, an FDA approved drug for treatment of Gaucher Disease. Our preliminary studies demonstrate that eliglustat promotes accumulation of mitotoxic ceramides with resultant shift from survival mitophagy to lethal mitophagy and subsequent cancer cell death. Moreover, we show that eliglustat suppresses tumor growth at clinically achievable doses in TNBC tumor-bearing mice and that the anti-cancer effects of eliglustat are associated with pronounced increases in tumor infiltrating CD4+ and CD8+ T-cells, suggesting an additional role of eliglustat in potentiating an anti-tumor immune response. The primary objectives of this proposal are to establish novel utility for eliglustat as an ‘immunometabolic adjuvant’ for the treatment of TNBC and to also define the mechanism(s) by which eliglustat potentiates an anti-cancer immune response. To test this, we will assess the anti-cancer efficacy of eliglustat in patient-derived xenograft (PDX) models generated from patients with primary treatment-naïve TNBC that did or did not go on to respond to chemotherapy (Specific Aim 1a). To test whether the combination of eliglustat plus anti-PD-L1 yields improved anti-cancer effects compared to either treatment alone, we will use the BRCA1co/co; MMTV-Cre; p53+/- and 4T1 orthotopic syngeneic mouse models of TNBC (Specific Aim 1b). Primary endpoints of interest for in vivo studies will be overall survival and tumor growth; effects on the tumor immunophenotype following intervention will be assess using multiplex immunofluorescence panels and single cell transcriptomics for single cell-level expression profiling of tissues. We also aim to define the mechanisms by which eliglustat induces an anti-cancer immune response. First, we will evaluate the effect of eliglustat on cGAS-STING signaling proteins and downstream pathway activities in TNBC cells (Specific Aim 2a). Next, we will use advanced mass spectrometry technologies coupled with novel isolation methods for extracellular vesicles (EVs) to define the MHC-I bound peptidome on surfaces of TNBC cells and TNBC-derived circulating and intra-tumor EVs following eliglustat treatment. ELIspot and Cytotoxic T Cell-based tumor killing live-cell assays will be used to test the functionality of EVs on activating T-cells ex vivo (Specific Aim 2b). If successful, our potential findings will provide key pre- clinical evidence for the use of eliglustat and justification for moving eliglustat into early phase clinical trials. Given that eliglustat is already FDA-approved for another indication, it has high potential to be readily translated into clinical use, and potentially providing a new paradigm for cancer immunotherapy.