Efficacy of PDI inhibitors in glioblastoma

 描述（由申请人提供）：蛋白质二硫键异构酶（PDI）通过介导氧化蛋白质折叠在维持细胞稳态中发挥关键作用。催化内质网（ER）中二硫键的形成、断裂和重排，并具有伴侣蛋白活性。越来越多的证据表明，PDI支持几种癌症的生存和进展，最重要的是脑癌。癌细胞需要更高水平的PDI来科普显著的ER应激和蛋白质合成的整体增加以维持快速增殖。蛋白质合成的增加导致ER中存在大量错误折叠的蛋白质，需要通过PDI重新折叠。因此，癌细胞比正常细胞更容易受到PDI抑制，使PDI成为治疗脑癌的新的令人兴奋的靶点。虽然PDI仍然是一个非常有前途的肿瘤学靶点，但目前还没有PDI抑制剂处于临床开发阶段。目前迫切需要开发针对脑癌关键通路的药物。以前对神经胶质瘤的靶向治疗尝试没有产生治愈。由于PDI是协调快速增殖所必需的整个过程的枢纽，因此选择性阻断其功能将导致ER应激增加，从而导致细胞增殖。 癌细胞的死亡。这种方法与以前的尝试截然不同，以前的尝试靶向单一蛋白质，导致容易逃逸和肿瘤复发。以前，我们发现了一类新的和不可逆的PDI抑制剂，其选择性地结合到PDI，并表现出显着的体内功效，没有明显的全身毒性。最近，我们进行了高通量筛选，并鉴定了代表迄今为止发现的最有效的PDI抑制剂的几种nM PDI抑制剂。我们建议优化和表征这些化合物，以选择治疗多形性胶质母细胞瘤（GBM）的临床线索。为了确定PDI信号传导在癌症进展中的意义及其抑制对肿瘤生长的影响，我们提出了以下目标。目的1：验证PDI作为靶点的可行性，确定PDI在GBM细胞系中的表达水平，筛选ER应激基因。目标二：进行基于结构和ADMET指导的先导化合物优化活动，以选择具有理想效价、选择性和PK特性的前5种化合物。目标3：在一组GBM细胞系中使用Bru-Seq技术对来自Aim 2的前5种化合物作为单药以及与替莫唑胺和放射（TMZ/IR）联合使用进行机制研究。目的4：确定PDI抑制剂作为单一药剂和与TMZ/IR组合在患者来源的异种移植物（PDX）模型中的体内功效。

 DESCRIPTION (provided by applicant): Protein disulfide isomerase (PDI) has a key role in maintaining cellular homeostasis by mediating oxidative protein folding. It catalyzes disulfide bond formation, breakage and rearrangement in the endoplasmic reticulum (ER), and possesses chaperone protein activity. Increasing evidence suggests that PDI supports the survival and progression of several cancers and most significantly brain cancer. Cancer cells require higher levels of PDI to cope with significant ER stress and global increase in protein synthesis to sustain rapid proliferation. Increased protein synthesis leads to an abundant presence of misfolded proteins in the ER that need to be refolded by PDI. As such, cancer cells are more vulnerable to PDI inhibition than normal cells making PDI a new and exciting target to treat brain cancer. Although PDI remains a very promising oncology target, currently there are no PDI inhibitors under clinical development. There is an urgent need to develop drugs targeting essential pathways in brain cancer. Previous attempts at targeted therapy for glioma did not produced cures. Since PDI is a hub for orchestrating an entire process essential for rapid proliferation, selective blockade of its function will result in increased ER stress leading to the death of cancer cells. This approach is drastically different from previous attempts that target a single protein leading to facile escape and tumor recurrence. Previously, we discovered a class of novel and irreversible PDI inhibitors that selectively bind to PDI and demonstrated significant in vivo efficacy with no apparent systemic toxicity. More recently, we performed a high throughput screen and have identified several nM inhibitors of PDI representing the most potent PDI inhibitors discovered to date. We propose to optimize and characterize these compounds to select clinical leads for the treatment of glioblastoma multiforme (GBM). To determine the significance of PDI signaling in cancer progression and the effect of its inhibition on tumor growth, we propose the following aims. Aim 1: To validate PDI as a target and to determine the expression levels of PDI and select ER stress genes in GBM cell lines. Aim 2: To perform a structure-based and ADMET-guided lead optimization campaign to select the top 5 compounds with desirable potency, selectivity, and PK properties. Aim 3: To perform mechanistic studies of top 5 compounds from Aim 2 as single agents and in combination with temozolomide and radiation (TMZ/IR) using Bru-Seq technology in a panel of GBM cell lines. Aim 4: To determine in vivo efficacy of PDI inhibitors, as a single agent and in combination with TMZ/IR in patient-derived xenograft (PDX) models.