Developing novel combination therapies for pancreatic cancer

项目总结/摘要 胰腺导管腺癌是一种致死性疾病。对于大多数患者化疗 是唯一的治疗选择，几乎所有患者都会复发耐药疾病。核苷 类似物吉西他滨是PDAC患者的一线药物和目前的标准治疗。当 联合吉西他滨、厄洛替尼或白蛋白结合型紫杉醇可增加非肿瘤患者的中位生存期， 可切除的疾病分别为约0.3至约1.8个月。5年生存率约为6%。显然更有效 需要治疗。 我们建议为PDAC患者开发有效的治疗方法。我们的数据表明， 吉西他滨+BET（布罗莫结构域末端外结构域）抑制剂JQ 1以及JQ 1 + PARP 1/2抑制剂奥拉帕尼在体外PDAC细胞中诱导强烈协同细胞毒性。值得注意的是， JQ 1+吉西他滨的研究支持体外数据，并显示该组合诱导了 携带患者来源的异种移植（PDX）肿瘤的小鼠。我们提出的两种组合的协同作用， 在表达突变型KRAS的PDAC细胞中，评估是明显的，突变型KRAS是一种与肿瘤细胞的不良增殖相关的肿瘤细胞特征。 临床结果数据表明，JQ 1+吉西他滨和JQ 1+奥拉帕尼可以包含有效的抗肿瘤活性。 治疗PDAC。 JQ 1是一种新型靶向小分子，可与BET蛋白的乙酰基赖氨酸结合口袋结合， 主要是BRD 2和BRD 4。这种结合抑制了BRD 2/4依赖性转录因子的结合。 聚集体与组蛋白的乙酰化赖氨酸残基结合，从而抑制依赖于 这个机制。该提案中的数据显示了JQ 1诱导DNA损伤，抑制 G2期细胞周期调节蛋白CDC 25 B和DNA修复蛋白Ku 80和BRCA 2的体内表达。 基于我们的研究结果和相关文献，我们假设JQ 1诱导的DNA损伤， CDC 25 B和随后的细胞周期失调使PDAC细胞对吉西他滨敏感。我们还假设， 根据我们的研究结果和相关文献，JQ 1诱导Ku 80和BRCA 2的抑制， DNA修复的抑制使PDAC肿瘤对PARP抑制剂敏感。我们建议评估疗效 和JQ 1+吉西他滨（Aim 1）和JQ 1+奥拉帕尼（Aim 2）的协同作用机制，使用转染的PDX- 体外衍生细胞系和我们独特的体内PDX模型组， 肿瘤起源的特征。我们还建议鉴定其他蛋白质，这些蛋白质有助于 JQ 1的细胞毒性机制（目的3）。 拟议的工作是朝着我们的长期目标迈出的重要一步， 治疗PDAC患者。

PROJECT SUMMARY/ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease. For the majority of patients chemotherapy is the only therapeutic option, and virtually all patients relapse with drug resistant disease. The nucleoside analogue gemcitabine is the frontline agent and current standard of care for patients with PDAC. When combined with gemcitabine, erlotinib or nab-paclitaxel increases median survival of patients with non- resectable disease by ~0.3 to ~1.8 months, respectively. The five-year survival is ~6%. Clearly more effective therapies are needed. We propose to develop effective therapy for patients with PDAC. Our data demonstrate that the combinations of gemcitabine + the BET (bromodomain extra-terminal domain) inhibitor JQ1 and also of JQ1 + the PARP 1/2 inhibitor olaparib induce strongly synergistic cytotoxicity in PDAC cells in vitro. Notably, a pilot study with JQ1 + gemcitabine supports in vitro data, and shows that this combination induces regressions in mice bearing patient-derived xenograft (PDX) tumors. The synergy of both combinations that we propose to evaluate was evident in PDAC cells that express mutant KRAS, a tumor cell characteristic associated with poor outcome clinically. The data suggest that JQ1 + gemcitabine and JQ1 + olaparib may comprise effective therapy for PDAC. JQ1 is a novel targeted small molecule that binds to acetyl lysine binding pockets of BET proteins, predominantly BRD2 and BRD4. This binding inhibits the association of BRD2/4-dependent transcriptional aggregates to acetylated lysine residues of histones, thereby inhibiting expression of proteins dependent on this mechanism. Data in this proposal show the novel findings that JQ1 induces DNA damage, inhibits expression of the G2 cell cycle regulator protein CDC25B and DNA repair proteins Ku80 and BRCA2 in vivo. We hypothesize, based on our findings and relevant literature, that JQ1-induced DNA damage, inhibition of CDC25B and consequent cell cycle dysregulation sensitize PDAC cells to gemcitabine. We also hypothesize, based on our findings and relevant literature, that JQ1-induced inhibition of Ku80 and BRCA2 and consequent suppression of DNA repair sensitizes PDAC tumors to PARP inhibitors. We propose to evaluate the efficacy and mechanisms of synergy of JQ1 + gemcitabine (Aim 1) and JQ1 + olaparib (Aim 2) using transfected PDX- derived cell lines in vitro and our unique panel of in vivo PDX models that retain specific biologic and genetic characteristics of their tumors of origin. We also propose to identify additional proteins that contribute to the cytotoxic mechanism of JQ1 (Aim 3). The proposed work comprises an essential step toward our long-range goal of developing effective therapy for patients with PDAC.