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

项目总结/摘要 同源重组（HR）修复缺陷型癌症依赖于聚合酶θ（POLq）介导的 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 耐药状态，其中POLq限制了过量的DNA末端切除和RAD 51加载，防止了DNA末端的转移。 有毒中间体的积累。POLq缺乏也与微核有关， 与先天免疫的激活有关通过高通量的小分子筛选， 最近发现抗生素新生霉素（NVB）作为一种特异性POLq抑制剂，可选择性杀死HR缺陷型 细胞在体外和体内，包括那些获得性PARP抑制剂耐药性，表明NVB可能是 可单独或与PARP抑制剂组合用于治疗具有HR改变的癌症。NVB还诱导 微核和随后的cGAS/STING途径激活。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物模型， 包括那些PARP敏感的和那些获得性PARP抑制剂耐药性的， 研究了NVB与PARP抑制剂talazoparib联合的反应和药效学，以比较 组合抗肿瘤和生物学功效与通过单一疗法实现的功效相比。药效学效应将 使用g-H2 AX、pRPA和RAD 51病灶作为DNA损伤、末端切除和RAD 51的生物标志物进行评估 加载，分别，试点其效用的临床试验。在第二个具体目标中，我们将进行第一阶段 NVB单药治疗和NVB联合Talazoparib治疗晚期实体瘤患者的临床试验 包含人力资源变更。单药治疗研究将采用BOIN设计，以确定推荐的 2期剂量的慢性单药治疗和联合治疗试验将采用瀑布设计来定义MTD 二维剂量矩阵上的轮廓。两项研究均将评价药代动力学参数， 结合用于药效学终点的成对活检，以建立机制证据。最低 NVB的生物学有效剂量将在单药治疗试验中确定，这将指导临床试验中的剂量。 组合研究在第三个特定目标中，将研究NVB单独使用和与talazoparib联合使用的 体外以及免疫活性基因工程小鼠中cGAS/STING活化的诱导 BRCA缺陷型乳腺癌模型。NVB和NVB/Talazoparib对小鼠免疫功能的影响 将全面表征微环境，并在不存在的情况下评估抗肿瘤活性 和免疫检查点阻断的存在。总之，本项目的临床前和临床研究 设计用于在HR缺陷型癌症的医疗设备中促进NVB介导的POLq抑制。

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.