Inhibition of wild-type IDH1 as a ferroptosis-inducing therapeutic approach for the treatment of malignant glioma.

我们的实验室最近的研究(Stegh和他的同事，细胞报告，2017；Wahl和他的同事，癌症 研究表明，IDH1野生型(IDH1-wt)在2/3的HGG中高表达 缺乏IDH1R132H突变的)。两者都有 独自一人 而当 Wt-IDH1的遗传和药理抑制， 与放射治疗(RT)相结合可减缓患者来源的HGG异种移植的生长。 Wt-IDH1过表达促进颅内HGG生长分子水平 ， 。浅谈GBM 产生过量的NADPH，这是一种限速还原剂，驱动单核苷酸的生物合成。 不饱和脂肪酸(MUFA)。此外，NADPH产量的增加还会增加谷胱甘肽(GSH) 水平，降低活性氧(ROS)，激活磷脂过氧化物酶谷胱甘肽过氧化物酶4 (Gpx4)-驱动脂质修复，并抑制含有多不饱和脂肪酸(PUFA)的堆积 过氧化脂质，已知的铁下垂的执行者。 基于这些发现，我们推测wt-IDH1通过增强脂质修复，升高MUFA 质膜磷脂中可氧化多不饱和脂肪酸的生物合成和置换拮抗 铁下垂，一种最近发现的细胞死亡形式，作为一种范式转变迅速得到认可 专门针对癌细胞的策略。我们进一步假设wt-idh1抑制与 已知的铁性下垂的诱导剂，包括RT和免疫介导的检查点抑制，以对抗HGG 进步。对于wt-IDH1的药理抑制，我们使用并表征了13I，一种新的 类竞争性-不饱和烯酮，由AbbVie开发。13I对wt-IDH1酶活性的抑制作用 活性，通过共价结合到NADP+结合口袋。我们的数据表明，13I促进了铁性下垂， 是脑穿透性的，就像基因消融一样，减缓IDH1的进展并延长其存活期 HGG荷瘤小鼠，单独及与RT联合应用。我们将在三个具体目标上检验这些假设： 目的1：确定wt-IDH1对从头合成脂肪酸和膜磷脂的影响 抑制铁性下垂的组合物。 目的2.确定wt-IDH1如何促进Gpx4依赖的脂质修复和拮抗铁性下垂。 目的3：确定wt-IDH1的遗传和药物失活是否会放大铁性下垂 对RT和免疫检查点阻断的反应并拮抗HGG进展。 目标和长期目标。我们将认证wt-IDH1为HGG中铁性下垂的调节器，并将 一种新型NADP+竞争性抑制剂用于治疗验证wt-IDH1的药理抑制作用 策略。这些研究的结果预计将为IND支持研究评估的设计提供参考 ~(13)I作为抗HGG辅助治疗的潜力。

Our laboratories recent studies (Stegh and colleagues, Cell Report, 2017; Wahl and colleagues, Cancer Research, 2017) indicated that IDH1 wild-type (IDH1-wt) is overexpressed in 2/3 of HGG (referred to here as `IDH1-wthigh GBM') that lack IDH1R132H mutation. Both alone while genetic and pharmacological inhibition of wt-IDH1, and in combination with radiation therapy (RT) slows the growth of patient-derived HGG xenografts 5,6 overexpression of wt-IDH1 promotes intracranial HGG growth molecular levels, wt-IDH1 high , . On GBM produce excess NADPH, which serves as a rate-limiting reductant that drives the biosynthesis of mono- unsaturated fatty acids (MUFAs). In addition, enhanced NADPH production increases glutathione (GSH) level, reduces reactive oxygen species (ROS), activates phospholipidperoxidase glutathione peroxidase 4 (GPX4)-drivenlipid repair, and dampensthe accumulation of polyunsaturated fatty acid (PUFA)-containing lipid peroxides, known executioners of ferroptosis. Based on these findings, we hypothesize that wt-IDH1 through enhanced lipid repair, heightened MUFA biosynthesis and displacement of oxidizable PUFAs from plasma membrane phospholipids antagonizes ferroptosis, a recently discovered form of cell death has rapidly gained recognition as a paradigm shifting strategy to specifically target cancer cells. We further hypothesize that wt-IDH1 inhibition cooperates with known inducers of ferroptosis, including RT and immune-mediated checkpoint inhibition, to antagonize HGG progression. For the pharmacological inhibition of wt-IDH1, we have used and characterized 13i, a first-in- class competitive -unsaturated enone, developed by AbbVie. 13i potently inhibits wt-IDH1 enzymatic activity, by covalently binding to the NADP+ binding pocket. Our data indicate that 13i promotes ferroptosis, is brain-penetrant, and like genetic ablation, reduces progression and extends the survival of IDH1-wthigh HGG bearing mice, alone and in combination with RT. We will test these hypotheses in three Specific Aims: Aim 1: Determine how wt-IDH1 impacts de novo fatty acid biosynthesis and membrane phospholipid composition to inhibit ferroptosis. Aim 2. Determine how wt-IDH1 promotes GPX4-dependent lipid repair and antagonizes ferroptosis. Aim 3: Determine if genetic and pharmacological inactivation of wt-IDH1 amplifies ferroptosis in response to RT and immune checkpoint blockade and antagonizes HGG progression. Objectives and long-term goals. We will credential wt-IDH1 as regulator of ferroptosis in HGG and will validate the pharmacological inhibition of wt-IDH1 using a novel NADP+ competitive inhibitor as a therapeutic strategy. Results from these studies are expected to inform the design of IND-enabling studies evaluating the potential of 13i as adjuvant for anti-HGG therapy.