Novobiocin-mediated polymerase theta inhibition in homologous recombination repair-deficient cancers

项目摘要/摘要 同源重组(HR)修复缺陷癌依赖于聚合酶(POLQ)介导 DNA末端连接，因此POLQ是这些癌症的候选靶点。这种依赖延伸到PARP 抑制物抵抗状态，其中POLQ限制过多的DNA末端切除和RAD51加载，防止 有毒中间体的堆积。POLQ缺乏症也与微核有关，这是一种过程 与先天免疫的激活有关。通过高通量的小分子筛查，我们有 最近发现抗生素novobiocin(NVB)是一种特异的POLQ抑制剂，可以选择性地杀死HR缺陷 体外和体内细胞，包括那些具有获得性PARP抑制剂耐药性的细胞，提示NVB可能是 在治疗HR改变的癌症时，单独或与PARP抑制联合使用是有用的。NVB还诱导 HR缺陷细胞的微核和随后的cGAS/STAR通路激活。在第一个具体目标中， BRCA突变乳腺癌、卵巢癌和胰腺癌的多细胞系和患者来源的异种移植模型 包括对PARP抑制剂敏感和具有获得性PARP抑制剂耐药性的患者， 诺维本与PARP抑制剂他唑普利联用的疗效及药效学比较 联合抗肿瘤和生物疗效优于单一疗法。药效学效应将 用g-H_2AX、PrPA和RAD51作为DNA损伤、末端切除和RAD51的生物标志物进行评估 分别加载以试验其用于临床试验的效用。在第二个具体目标中，我们将进行第一阶段 诺维本单药和诺维本联合他唑普利治疗晚期实体瘤的临床研究 藏匿人事变动。单一疗法研究将利用Boin设计来确定推荐的 慢性单一疗法和联合试验的第二阶段剂量将利用瀑布设计来定义MTD 二维剂量矩阵上的等高线。这两项研究都将评估药代动力学参数和 结合药效学终点的配对活检以建立机制证明。最低要求 NVB的生物有效剂量将在单一疗法试验中确定，这将指导 联合研究。在第三个具体目标中，将研究NVB单独使用和与他唑帕利布联合使用 在体外诱导cGAS/STIN激活，以及在具有免疫功能的基因工程小鼠中 BRCA缺陷型乳腺癌模型的建立。诺维本及诺维本/他唑巴对机体免疫功能的影响 将对微环境进行全面表征，并将在缺席的情况下评估抗肿瘤活性 以及免疫检查站封锁的存在。综上所述，该项目的临床前和临床研究 旨在促进NVB介导的POLQ抑制在HR缺陷型癌症中的应用。

PROJECT SUMMARY/ABSTRACT Homologous recombination (HR) repair-deficient cancers are dependent on polymerase theta (POLq)-mediated DNA end joining, so that POLq is a candidate target for these cancers. This reliance extends to the PARP inhibitor-resistant state, where POLq limits excessive DNA end resection and RAD51 loading, preventing the accumulation of toxic intermediates. POLq deficiency has also been linked to micronucleation, a process associated with activation of innate immunity. Through high-throughput small molecule screens, we have recently identified the antibiotic novobiocin (NVB) as a specific POLq inhibitor that selectively kills HR-deficient cells in vitro and in vivo, including those with acquired PARP inhibitor resistance, suggesting that NVB may be useful alone or in combination with PARP inhibition in treating cancers with HR alterations. NVB also induces micronucleation and consequent cGAS/STING pathway activation in HR-deficient cells. In the first Specific Aim, multiple cell line and patient-derived xenograft models of BRCA-mutant breast, ovarian and pancreatic cancer, including those that are PARP inhibitor-sensitive and those with acquired PARP inhibitor resistance, will be studied for response and pharmacodynamics of NVB combined with the PARP inhibitor talazoparib to compare combinatorial antitumor and biological efficacy to that achieved by monotherapy. Pharmacodynamic effects will be assessed using g-H2AX, pRPA and RAD51 foci as biomarkers of DNA damage, end resection and RAD51 loading, respectively, to pilot their utility for clinical trial. In the second Specific Aim, we will conduct Phase 1 clinical trials of NVB monotherapy and NVB combined with talazoparib in patients with advanced solid tumors harboring HR alterations. The monotherapy study will utilize a BOIN design to determine the recommended phase 2 dose of chronic monotherapy and the combination trial will utilize a waterfall design to define the MTD contour over a two-dimensional dose matrix. Both studies will evaluate pharmacokinetic parameters and incorporate paired biopsies for pharmacodynamic endpoints to establish proof-of-mechanism. The minimum biological effective dose of NVB will be determined in the monotherapy trial, which will guide dosing in the combination study. In the third Specific Aim, NVB used alone and combined with talazoparib will be studied for induction of cGAS/STING activation in vitro, as well as in an immunocompetent genetically engineered mouse model of BRCA-deficient breast cancer. The effects of NVB and NVB/talazoparib on the immune microenvironment will be comprehensively characterized and antitumor activity will be assessed in the absence and presence of immune checkpoint blockade. Taken together, the preclinical and clinical studies in this project are designed to advance NVB-mediated POLq inhibition in the armamentarium for HR-deficient cancers.