Investigation of DNA Damaging Agents in GIST with Metabolic Dysfunction

项目总结/摘要 胃肠道间质瘤（GIST）是一种罕见疾病，在美国有约3，000例新发恶性病例。 每年。突变型SDH（琥珀酸脱氢酶）A/B/C/D亚单位GIST占所有病例的<7.5%， 在遗传性副神经节瘤-GIST综合征（又名家族性副神经节瘤-GIST综合征）的背景下， 影响儿童、青少年和年轻人。这些GIST对伊马替尼具有固有耐药性，而舒尼替尼 和瑞戈非尼的疗效有限（<20%的应答率）。到目前为止，没有药物在此GIST中显示出获益 人口已知SDH复合物调节细胞代谢中的关键酶促反应， SDH表达的丧失是肿瘤发生中的关键事件。目前，所有SDH研究的主要障碍 缺乏人类细胞系或动物模型。也不知道新陈代谢是如何具体地 在mSDH GIST细胞中重新编程，以及这如何导致药物敏感性，以及也可能导致 合成杀伤力的出现。但是，在一项针对副神经节瘤患者的小型临床研究中， 野生型SDHB，肿瘤对DNA损伤剂替莫唑胺（TMZ）有反应。我们的团队现在已经 开发了第一个患者来源的mSDH（A/B/C）GIST细胞系。在加州大学圣地亚哥分校，我们也有初步的 我们的患者来源的mSDH GIST细胞在体外是TMZ敏感的，并且我们的mSDH GIST细胞群在体外是TMZ敏感的。 GIST患者对TMZ治疗有反应。我们假设mSDH GIST具有不同的代谢 在一些实施方案中，所述药物组合物可导致DNA紊乱，并且易受单独的新药物或与DNA损伤剂组合的新药物的影响。我们将 研究如下：目的1，我们将在一项II期、单组研究中评估TMZ的疗效， 晚期mSDH GIST患者，目的是确定6个月时的总体缓解率（主要 目的），以及无进展生存期、总生存期和TMZ安全性/耐受性，以及血清 TMZ反应的代谢物生物标志物。在目标2中，我们将描述中心碳的重编程 使用13 C代谢通量分析（MFA）通过mSDH GIST进行代谢。我们将使用同位素示踪剂， 光谱，和计算算法来执行MFA，以确定克雷布斯循环的重要作用 促进癌细胞生长的酶。在目标3中，我们将确定细胞和代谢 mSDH GIST在单独使用TMZ或与经验证的合成致死性药物联合使用时的脆弱性， 确定mSDH GIST协同联合疗法。总的来说，这代表了一种新的方法， 重新利用FDA批准的药物TMZ来治疗目前没有有效疗法的孤儿病。我们 预计这些研究将：1）确定mSDH GIST的第一种有效疗法; 2）产生新的见解， mSDH GIST的代谢重编程;和3）确定mSDH GIST中TMZ细胞毒性的机制。 这些研究有可能对治疗mSDH GIST以及其他疾病产生直接临床影响。 mSDH癌症（肾细胞、甲状腺和副神经节瘤）。

PROJECT SUMMARY/ABSTRACT Gastrointestinal stromal tumor (GIST) is an orphan disease with ~3,000 new malignant cases in the U.S. annually. Mutant SDH (succinate dehydrogenase) A/B/C/D subunit GISTs comprise <7.5% of all cases and occur in the setting of inherited Carney-Stratakis Syndrome (aka Familial Paraganglioma-GIST Syndrome), which affects children, adolescents, and young adults. These GISTs are inherently resistant to imatinib, while sunitinib and regorafenib have limited efficacy (<20% response rates). To date, no drug has shown benefit in this GIST population. It is known that the SDH complex regulates critical enzymatic reactions in cellular metabolism and loss of SDH expression is a critical event in tumorigenesis. At present, the major impediment to all SDH research has been the lack of human cell lines or animal models. It is also unknown how metabolism is specifically reprogrammed in mSDH GIST cells and how this leads to drug susceptibility, as well as may also result in the emergence of synthetic lethalities. But, in a small clinical study of paraganglioma patients, only mSDHB, but not wild-type SDHB, tumors responded to the DNA damaging agent, temozolomide (TMZ). Our group has now developed the first patient-derived mSDH (A/B/C) GIST cell lines. At UC San Diego, we also have preliminary evidence that our patient-derived mSDH GIST cells are TMZ-sensitive in vitro and that a cohort of our mSDH GIST patients have responded to TMZ treatment. We hypothesize that mSDH GIST possess distinct metabolic derangements and are vulnerable to novel agents alone or in combination with DNA damaging agents. We will investigate this in the following: Aim 1, we will evaluate the efficacy of TMZ in a Phase II, single arm study in advanced mSDH GIST patients with the objective of determining overall response rate at 6 months (primary objective), as well as progression-free survival, overall survival, and TMZ safety/tolerability, and serum metabolites biomarkers of TMZ response. In Aim 2, we will characterize reprogramming of central carbon metabolism by mSDH GIST using 13C metabolic flux analysis (MFA). We will apply isotope tracers, mass spectrometry, and computational algorithms to perform MFA in order to identify important roles of Krebs Cycle enzymes in promoting cell growth in cancer cells. In Aim 3, we will determine the cellular and metabolic vulnerabilities of mSDH GIST in response to TMZ alone, or in combination with validated synthetic lethalities, to identify synergistic combination therapies for mSDH GIST. Overall, this represents a novel approach for repurposing an FDA-approved drug, TMZ, to treat an orphan disease without current effective therapy. We anticipate these studies will: 1) identify the first efficacious therapy for mSDH GIST; 2) yield new insights into metabolic reprogramming of mSDH GIST; and 3) define the mechanism of TMZ cytotoxicity in mSDH GIST. These studies have the potential for immediate clinical impact for treating mSDH GIST, as well as other mSDH cancers (renal cell, thyroid, and paraganglioma).