Investigation of DNA Damaging Agents in GIST with Metabolic Dysfunction

项目摘要/摘要 胃肠道间质瘤(GIST)是一种孤儿疾病，在美国约有3,000例新的恶性肿瘤病例。 每年一次。突变的SDH(琥珀酸脱氢酶)A/B/C/D亚单位GIST占所有病例的7.5%，并发生 在遗传性Carney-Stratakis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对伊马替尼具有天然耐药性，而舒尼替尼 和瑞格非尼的疗效有限(缓解率为20%)。到目前为止，还没有药物在GIST中显示出疗效 人口。已知SDH复合体调节细胞代谢中的关键酶反应和 SDH表达缺失是肿瘤发生过程中的重要事件。目前，所有SDH研究的主要障碍是 一直缺乏人类细胞系或动物模型。新陈代谢是如何特定的也是未知的。 在mSDH GIST细胞中重新编程以及这如何导致药物敏感性以及可能导致 合成杀伤力的出现。但是，在一项对副神经节瘤患者的小型临床研究中，只有mSDHB，而不是 野生型SDHB，肿瘤对DNA损伤剂替莫唑胺(TMZ)有反应。我们小组现在已经 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，我们也有预赛 我们的患者来源的mSDH GIST细胞在体外对TMZ敏感的证据，以及我们的mSDH队列 GIST患者对TMZ治疗有反应。我们假设mSDH GIST具有明显的代谢 并且容易受到单独或与DNA损伤剂联合使用的新制剂的影响。我们会 研究如下：目标1，我们将在第二阶段的单臂研究中评估TMZ的疗效 晚期mSDH GIST患者，目标是在6个月内确定总应答率(初级 目标)，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新编程 代谢由mSDH GIST使用13C代谢通量分析(MFA)。我们将应用同位素示踪剂，质量 光谱分析和执行MFA的计算算法，以确定Krebs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的漏洞单独响应TMZ，或结合验证的合成致命性，以 确定治疗mSDH GIST的协同联合疗法。总体而言，这代表了一种新的方法 改变FDA批准的药物TMZ的用途，以治疗目前没有有效治疗的孤儿疾病。我们 预计这些研究将：1)确定治疗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；3)明确了TMZ在mSDH GIST中的细胞毒性机制。 这些研究有可能对治疗mSDH GIST以及其他疾病产生直接的临床影响 MSDH癌(肾细胞癌、甲状腺癌和副神经节瘤)。

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).