Elucidating Cancer Risk in BRCA2 and RAD51 Variants

项目总结 发现并根据基因发现采取行动的精准医学的新时代无意中创造了一个巨大的 当遇到不确定意义的变种(VUS)时的临床两难境地。被确认为BRCA或 接受遗传咨询的RAD51 VUS携带者经历困惑、焦虑和潜在的 误导的治疗计划。目前的估计表明，10%-20%的BRCA测序结果是 仅在美国就代表数千名患者的VU。这些数字可能会随着精确度的提高而上升 药品和商业上可用的基因检测服务正在迅速部署。BRCA2 RAD51蛋白在DNA双链断裂的同源定向修复(HDR)中起核心作用 (DSB)。在医学肿瘤学的背景下，仍然缺乏破译HDR VUS的功能诊断工具。 这是一个关键问题，因为生殖系HDR突变使个体容易患癌症的高风险，而体细胞 在肿瘤中发现的突变会极大地影响治疗计划。例如，合成致命策略 使用PARP抑制剂目前正被用于肿瘤学，以选择性地靶向HDR缺陷的肿瘤。 因此，正确解释体瘤VUS可以指导治疗方案的选择。功能分析 确定VUS的病理结果是迫切需要的，以提供癌症的临床指导。 风险和治疗方案。我们的长期目标是将分子和机制的清晰度带到 HDR用来修复DNA断裂的操作途径。通过使用高度协同的生化和 通过遗传学的方法，我们旨在阐明VUS如何影响BRCA2和RAD51功能。我们的中心假设 一种基于细胞和生化功能的方法将成功地区分致病和 无害的HDR VUS。在目标1中，我们将建立基于细胞的互补分析，从临床上 相关试剂可用于鉴定致病的BRCA2和RAD51变异体。整合肿瘤派生的 我们基于细胞的模型中的体细胞变异将使二线疗法或新疗法的体外测试成为可能 为临床实践提供信息的化合物，这些患者可以从靶向药物中受益。在目标2中，我们 将决定致病变异如何改变BRCA2和RAD51的生化功能。结果将是 用来进一步完善我们对病理性HDR变体的机械理解，以及如何进行生化 缺陷会转化为癌症风险的增加。我们的方法是创新的，因为我们拥有独特的技能和 以细胞和生化为基础的功能分析方法的发展，以剖析HDR机制 BRCA2和RAD51。拟议的研究具有重要意义，因为它将为以下方面奠定基础 具有有关降低风险步骤和分层的临床可操作信息的患者和医生 靶向治疗，如PARP抑制剂。此外，对病理变异的研究将提供洞察力 当HDR功能受损时，分子通路就会出错。

PROJECT SUMMARY The new era of precision medicine to discover and act upon genetic findings has inadvertently created a huge clinical dilemma when a variant of uncertain significance (VUS) is encountered. Patients identified as BRCA or RAD51 VUS carriers undergoing genetic counseling experience confusion, anxiety, and the potential for misguided treatment plans. Current estimates indicate that between 10-20% of BRCA sequencing results are VUS representing thousands of patients in the U.S. alone. These numbers will likely escalate as precision medicine and commercially available genetic testing services are being deployed at a rapid pace. The BRCA2 and RAD51 proteins play central roles in the homology-directed repair (HDR) of DNA double-strand breaks (DSBs). Functional diagnostic tools to decipher HDR VUS are still lacking in the setting of medical oncology. This is a critical issue as germline HDR mutations predispose individuals to a high risk for cancer while somatic mutations identified in tumors can dramatically impact treatment plans. For example, synthetic lethal strategies employing PARP inhibitors are currently being exploited in oncology to selectively target HDR deficient tumors. Therefore, the correct interpretation of a somatic tumor VUS can guide therapy selection. Functional assays to determine the pathological outcome of VUS are urgently needed to provide clinical guidance regarding cancer risk and treatment options. Our long-term objective is to bring molecular and mechanistic clarity to the operative pathways that HDR utilizes to repair DNA breaks. By using a highly synergistic biochemical and genetic approach, we aim to elucidate how VUS impact BRCA2 and RAD51 functions. Our central hypothesis is that a cell-based and biochemical functional approach will successfully differentiate pathogenic from harmless HDR VUS. In aim 1, we will establish cell-based complementation assays from which clinically relevant agents can be used to identify pathogenic BRCA2 and RAD51 variants. Integrating tumor-derived somatic variants into our cell-based models will enable in vitro testing of second-line therapies or novel compounds informing clinical practice of patients who could derive benefit from targeted agents. In aim 2, we will determine how pathogenic variants alter the biochemical functions of BRCA2 and RAD51. Results will be used to further refine our mechanistic understanding of pathological HDR variants and how biochemical defects translate into increased cancer risk. Our approach is innovative because of our unique skill set and development of robust cell-based and biochemical functional assays to dissect HDR mechanisms focused on BRCA2 and RAD51. The proposed research is significant because it will lay the groundwork to provide patients and physicians with clinically actionable information regarding risk reduction steps and stratification for targeted therapies such as PARP inhibitors. Furthermore, studies of pathological variants will provide insight into the molecular pathways that go awry when HDR functions are compromised.