Developing BRAF mutant and BRAF wild-type selective strategies for radiosensitization in Anaplastic Thyroid Cancer

项目总结 间变性甲状腺癌(ATC)是预后最差的实体瘤之一。 标准治疗包括最大限度的安全切除、外照射(EBRT)和细胞毒性治疗。 化疗。尽管如此，疾病复发率很高。本地/地区复发率为 对于ATC患者尤其困难，导致呼吸道和/或食道受损，这对 死亡和转移性传播。因此，需要新的疗法来改善疾病控制和 延长生存时间。最近，ATC的基因组图谱发现了RAS-RAS的高频突变- RAF-MEK-ERK通路(特别是BRAF和RAS)以及其他DNA损伤和细胞周期检查点 控制基因，包括TP53。我们的临床前数据支持激活的BRAFV600E突变促进 通过非同源末端连接修复(NHEJ)DNA对EBRT和基因毒性治疗的抵抗 修复途径。此外，用小分子抑制剂靶向抑制BRAFV600E会导致 BRAF突变体(BRAFm)ATC对EBRT的敏感性。此外，对BRAF突变细胞的处理 MEK-1/2抑制剂也具有放射增敏作用。由于BRAF野生型(BRAFwt)ATC占~60- 在70%的病例中，为BRAFwt ATC制定有针对性的放射增敏策略也至关重要。因此，我们 发现TP53突变体ATC可有效地被ATR和Wee1激酶抑制剂辐射增敏，突显出 这些肿瘤对G2/M细胞周期检查点的依赖性。最后，我们将探讨辐射敏化。 RAS突变体ATC，ATC的另一个常见的BRAFwt分子亚型的研究方法。在这项提案中，我们 将尝试多种策略来推进BRAFm和BRAFwt ATC患者的治疗。在目标1中，我们 将进行I期试验以确定达普拉非尼(BRAF抑制剂)的最大耐受量和 曲美替尼(MEK-1/2抑制剂)与EBRT同时用于BRAFm ATC，并确定 导致抗性的反应和分子途径。在目标2中，我们将进行机械研究，以 更好地了解BRAFm如何加速DNA修复，测试新的靶向治疗策略 DNA修复的组成部分，并开发和优化针对DNA修复的组合新策略 使用EBRT和其他遗传毒性疗法治疗BRAFm ATC。在目标3中，我们将尝试开发小说 通过测试针对TP53和RAS缺乏的不同靶向策略来治疗BRAF野生型ATC的策略 或在体外和体内突变ATC，以支持这些组合的未来临床测试。加在一起，这些 研究将提高我们对BRAF突变如何传递放射抗性的理解，并发现新的 肿瘤选择性联合治疗BRAF突变型和BRAF野生型ATC患者。

PROJECT SUMMARY Anaplastic thyroid cancer (ATC) remains one of the solid tumors that is associated with the poorest prognosis. Standard therapy includes maximal safe resection, external beam radiation therapy (EBRT), and cytotoxic chemotherapy. Despite this, there are high rates of disease recurrence. Local/regional recurrence is particularly difficult for patients with ATC, resulting in airway and/or esophageal compromise which contributes to mortality and metastatic dissemination. Novel therapies are thus needed to improve disease control and lengthen survival. Recently, genomic profiling of ATC has uncovered high frequency mutations in the RAS- RAF-MEK-ERK pathway (particularly BRAF and RAS), as well as other DNA damage and cell cycle checkpoint control genes, including TP53. Our preclinical data supports that an activating BRAFV600E mutation promotes resistance to EBRT and genotoxic therapies, through the non-homologous end-joining repair (NHEJ) DNA repair pathway. In addition, targeted inhibition of BRAFV600E with a small molecule inhibitor results in sensitization to EBRT in BRAF mutant (BRAFm) ATC. Furthermore, treatment of BRAF mutant cells with a MEK-1/2 inhibitor also results in radiosensitization. Since BRAF wild-type (BRAFwt) ATC accounts for ~ 60- 70% of cases, developing targeted strategies for radiosensitization in BRAFwt ATC is also critical. As such, we find that TP53 mutant ATC is effectively radiosensitized by ATR and Wee1 kinase inhibitors, highlighting the dependency of these tumors on the G2/M cell cycle checkpoint. Finally, we will explore radiation sensitization approaches for RAS mutant ATC, another common BRAFwt molecular subtype of ATC. In this proposal, we will attempt multiple strategies to advance therapy for patients with BRAFm and BRAFwt ATC. In Aim 1, we will perform a phase I trial to determine the maximally-tolerated doses of dabrafenib (BRAF inhibitor) and trametinib (MEK-1/2 inhibitor) to be used concurrently with EBRT for BRAFm ATC, and identify biomarkers of response and molecular pathways leading to resistance. In Aim 2, we will perform mechanistic studies to better understand how BRAFm leads to accelerated DNA repair, test novel therapeutic strategies targeting components of DNA repair, and develop and optimize novel strategies targeting DNA repair in combination with EBRT and other genotoxic therapies for BRAFm ATC. In Aim 3, we will attempt to develop novel strategies for treating BRAF wild-type ATC, by testing different targeted strategies for TP53 and RAS deficient or mutated ATC in vitro and in vivo to support future clinical testing of these combinations. Together, these studies will improve our understanding of how BRAF mutations impart radio-resistance, and identify new tumor-selective combinatorial approaches for treating patients with BRAF mutant and BRAF wild-type ATC.