Preclinical stroke trial with the PARP inhibitor veliparib

Parthanatos是一种细胞死亡信号通路，其中DNA的过度氧化损伤导致聚（ADP-核糖）聚合酶（PARP）的过度激活，然后刺激大聚（ADP-核糖）聚合物的形成，诱导凋亡诱导因子（AIF）从线粒体外膜释放。在细胞质中，AIF与巨噬细胞迁移抑制因子（MIF）形成复合物，并易位到细胞核中，MIF降解DNA并导致细胞死亡。对文献的回顾显示，23篇出版物支持parthanatos在13个不同实验室使用9种不同的PARP抑制剂（19项研究）或PARP1无效小鼠（6项研究）的年轻雄性小鼠和大鼠受到短暂性和永久性大脑中动脉闭塞（MCAO）的作用。一些研究表明MCAO后的治疗窗口期为4-6小时。在年轻的雌性大鼠中，来自两个实验室的两项研究基于使用两种不同的PARP抑制剂支持parthanatos的作用，而来自一个实验室的两项研究不支持年轻的雌性PARP1无效小鼠的作用。除了parthanatas介导的神经元细胞死亡外，大量文献表明PARP抑制剂可以通过干扰小胶质细胞中NFkB的转录、抑制MMP- 9的释放、限制血脑屏障损伤和出血症转化来减轻神经炎症。总的来说，大多数文献都强烈支持PARP抑制剂具有神经保护作用的科学前提，即使在MCAO后再灌注时给予也是如此。然而，没有MCAO的研究在已知具有衰老免疫系统和性激素保护减弱的老年动物中测试PARP抑制剂。由于老年动物被认为与人类中风人群有更大的翻译相关性，在进入临床中风试验之前，PARP抑制剂应该在老年动物和两性中进行测试。基于PARP抑制剂veliparib良好的脑穿透性及其在人体肿瘤试验中的安全性，我们建议在老年雄性和雌性小鼠MCAO后再灌注时测试PARP抑制剂veliparib。我们计划的主要结果是在一个月的时间里完成伸手到抓握的灵活性任务，这种任务在中风后的一个多月里会显示出持续的缺陷。次要结果包括其他四项感觉运动任务的短期缺陷，一个月时的恐惧条件认知，一个月时的脑萎缩，以及急性MRI检测病变体积，CBF和DTI与组织pH图的不匹配。该团队由具有30年MCAO临床前研究经验的PI、阐明兴奋毒性和中风模型中parthanatos信号的神经科学家、具有中风后小鼠神经行为测试专业知识的中风临床医生、具有25年开发用于中风和其他疾病的新脑成像模式经验的MR科学家以及具有啮齿动物多模态MR成像专业知识的MR科学家领导。该团队在实验性卒中方面有着悠久的合作历史，并高度致力于SPAN任务的科学严密性，作为六种候选药物的试验点，用于缺血性卒中再灌注治疗的辅助使用。

Parthanatos is a cell death signaling pathway in which excessive oxidative damage to DNA leads to over- activation of poly(ADP-ribose) polymerase (PARP), which then stimulates the formation of large poly(ADP- ribose) polymers that induce the release of apoptosis-inducing factor (AIF) from the outer mitochondrial membrane. In the cytosol, AIF forms a complex with macrophage migration inhibitory factor (MIF) that translocates into the nucleus where the MIF degrades DNA and produces cell death. A review of the literature reveals 23 publications that support a role for parthanatos in young male mice and rats subjected to transient and permanent middle cerebral artery occlusion (MCAO) based on the use of 9 different PARP inhibitors (19 studies) or PARP1 null mice (6 studies) from 13 different labs. Several studies indicate a therapeutic window of 4-6 h after MCAO. In young female rats, 2 studies from 2 labs support a role for parthanatos based on the use of 2 different PARP inhibitors, whereas 2 studies from one lab do not support a role in young female PARP1 null mice. In addition to parthanatos-mediated neuronal cell death, a body of literature indicates that PARP inhibitors can reduce neuroinflammation by interfering with NFkB transcription in microglia, suppressing MMP- 9 release, and limiting blood-brain barrier damage and hemorrhagic transformation. Overall, most of the literature strongly supports the scientific premise that a PARP inhibitor is neuroprotective, even when it is given at reperfusion after MCAO. However, no studies of MCAO have tested PARP inhibitors in aged animals known to have a senescent immunologic system and diminished protection by sex hormones. Because aged animals are thought to be more translationally relevant for the human stroke population, a PARP inhibitor should be tested in aged animals of both sexes before moving into clinical stroke trials. We propose testing the PARP inhibitor veliparib at reperfusion after MCAO in aged male and female mice based on its good brain penetration and its established safety in human oncology trials. Our planned primary outcome is one-month performance on a reaching-to-grasp dexterity task known to display sustained deficits for over a month after stroke. Secondary outcomes include short-term deficits in four other sensorimotor tasks, fear conditioning cognition at one month, brain atrophy at one month, and acute MRI determinations of lesion volume, CBF, and mismatch of DTI with tissue pH maps. The team is led by a PI with 30 years of experience in performing preclinical studies of MCAO, neuroscientists who elucidated parthanatos signaling in models of excitotoxicity and stroke, a stroke clinician with expertise in neurobehavior testing in mice after stroke, an MR scientist with 25 years of experience in developing new modalities of brain imaging for use in stroke and other disorders, and a MR scientist with expertise in multimodal MR imaging in rodents. The team has a long history of collaborating together on experimental stroke and is highly dedicated to the scientific rigor of the SPAN mission by serving as a test site for six candidate drugs for adjunct use with reperfusion therapies in ischemic stroke.