Time Domian Electron Paramagnetic Resonance Imaging

时域电子顺磁共振成像

• 批准号: 10702358
• 负责人: Murali Krishna
• 金额: $ 113.36万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10702358
• 关键词: 3-Dimensional; Aftercare; Agreement; Biochemical; Cell Line; Cell Nucleus; Characteristics; Chemicals; Chemoresistance; Chemotherapy and/or radiation; Chemotherapy-Oncologic Procedure; Clinical; Combined Modality Therapy; DNA Repair; DNA lesion; Dependence; Effectiveness; Electron Spin Resonance Spectroscopy; Hypoxia; Image; In Vitro; Kidney; Label; Magnetic Resonance Imaging; Magnetism; Maps; Measures; Metabolic; Metabolism; Methods; Monitor; Mus; Nature; Nude Mice; Organ; Oxidation-Reduction; Oxygen; Oxygen saturation measurement; Pancreatic Ductal Adenocarcinoma; Pathway interactions; Penetration; Pharmaceutical Preparations; Physiology; Pimonidazole; Process; Prodrugs; Protons; Pyruvate; Radiation; Radiation therapy; Research; Residual Tumors; Signal Transduction; Solid; Stains; Techniques; Testing; Time; Tissues; Toxic effect; Tracer; Tumor Oxygenation; Water; Width; Work; Xenograft Model; Xenograft procedure; aerobic glycolysis; anticancer treatment; base; cell killing; chemotherapy; cytotoxic; density; ds-DNA; gemcitabine; homologous recombination; improved; improved outcome; in vivo; kidney imaging; metabolic imaging; molecular imaging; pre-clinical; radioresistant; repaired; response; stem; synergism; treatment effect; treatment response; tumor; tumor hypoxia; tumor microenvironment

Dynamic range extension of pO2 imaging: In the preceding research, we examined and confirmed the utility of spin probe Ox071, deuterated version of Ox063, for both R1 and R2* based EPR oximetry. Due to the narrow line width and slower signal decay, it was expected that pO2 estimation using Ox071 is suitable not only in hypoxic tissue but also in less hypoxic tissue such as solid organs. In this work, we present our first 3D in vivo EPR oximetry study using Ox071 in comparison with Ox063 oximetry. The R2* change with [Ox071] and pO2 was calibrated using standard phantom solutions at 1,2,5,10 mM and 0, 2, 5, 10, 21%, respectively. In vivo EPR imaging of a mouse bearing MIA Paca-2 tumor was performed on successive days by using either Ox071 or Ox063. The spin density, pO2 maps, and pO2 histograms in the tumor regions marked by co-registration with MRI were similar between Ox063 and Ox071. Healthy kidney imaging was also performed on athymic mice using both Ox071 and Ox063. Ox071 oximetry showed more homogeneous pO2 profile in kidney compared with Ox063, suggesting that Ox071 is suitable for oximetry in tissue at higher pO2 range. Tumor microenvironment determinants in evofosfamide efficacy: Pancreatic ductal adenocarcinomas (PDACs) form hypovascular and hypoxic tumors which are difficult to treat with current chemotherapy regimens. Gemcitabine (GEM) is often used as a first line treatment for PDACs, but has issues with chemoresistance and penetration in the interior of the tumor. Evofosfamide, a hypoxia activated prodrug, has been shown to be effective in combination with GEM, although the mechanism of each drug on the other has not been established. We used two mouse xenografts from two cell lines (MIA Paca-2 and SU 86.86) with different tumor microenvironmetal characteristics to probe the action of each drug on the other. GEM treatment enhanced survival times in mice with SU.86.86 xenografts (HR =0.35, 95% CI=0.13 to 0.90 p=0.03) but had no effect on MIA Paca-2 mice (HR =0.91, 95% CI=0.37 to 2.25, p=0.84). Conversely, evofosfamide had no effect on SU86.86 mice and did not improve survival times to a statistically significant degree (HR=0.57, 95% CI=0.23 to 1.42, p=0.22). In MIA Paca-2 tumors, which were initially poorly perfused, electron paramagnetic resonance (EPR) imaging showed that oxygenation worsened when treated with GEM, providing a direct mechanism for the activation of evofosfamide by GEM and the effectiveness of evofosfamide and GEM combinations. Sublethal amounts of either treatment enhanced the toxicity of other treatment in vitro in Su86.86 but not in MIAPaca-2. Repair of double stranded DNA lesions was enhanced in the combination treatment in Su86.86 but not MIA Paca-2. A possible mechanism for the synergy between evofosfamide and GEM has been proposed. The synergy between GEM and evofosfamide appears to stem from the dual action of GEM's effect on tumor vasculature and the GEM inhibition of the homologous recombination DNA repair process. The relative importance of each pathway is dependent on the tumor microenvironment and merits further study. The hypoxia activated prodrug Evofosfamide improves tumor oxygenation. Tumors have regions with low. Levels of oxygen called hypoxic zones, These regions are resistant to radiation therapy and chemotherapy. Hypoxia activated prodrugs such as Evofosfamide are developed to specifically kill cells in hypoxic regions. In hypoxic tumor microenvironments, the strongly reducing redox state converts evofosfamide (TH-302) to a reduced form and releases a cytotoxic bromo-isophosphoramide (Br-IPM) moiety. This drug therefore preferentially attacks hypoxic regions in tumors where other standard anti-cancer treatments such as chemotherapy and radiation therapy are often ineffective. Various combination therapies with evofosfamide have been proposed and tested in preclinical and clinical settings. However, the treatment effect of evofosfamide monotherapy on tumor hypoxia has not been fully understood, partly due to the lack of quantitative methods to assess tumor pO2 in vivo. Here, we use quantitative pO2 imaging by EPR to evaluate the change in tumor hypoxia in response to evofosfamide treatment using two pancreatic ductal adenocarcinoma xenograft models; MIA Paca-2 tumors responding to evofosfamide and Su.86.86 tumors which do not respond. EPR imaging showed oxygenation improved globally after evofosfamide treatment in hypoxic MIA Paca-2 tumors, in agreement with the ex vivo results obtained from hypoxia staining by pimonidazole and in apparent contrast to the decrease in Ktrans observed in DCE MRI. The observation that evofosfamide not only kills the hypoxic region of the tumor but also improves oxygenation in the residual tumor regions provides a rationale for combination therapies using radiation and anti-proliferatives post evofosfamide for improved outcomes.

PO2成像的动态范围扩展：在前面的研究中，我们研究并确认了基于R1和R2**基于R2**的EPR氧仪的自旋探针OX071（剥离版本的OX063）的实用性。由于线宽度狭窄和信号衰减较慢，预计使用OX071的PO2估计不仅适用于低氧组织，而且适用于较少的低氧组织（例如固体器官）。在这项工作中，我们使用OX071与OX063的血氧仪相比，介绍了我们的第一个3D体内EPR血氧仪研究。使用标准幻影溶液分别以1,2,5,10 mm和0、2、5、10、21％的标准幻影溶液对R2*更改进行了校准。 通过使用OX071或OX063，在连续的几天进行了小鼠轴承MIA PACA-2肿瘤的体内EPR成像。在OX063和OX071之间，以MRI为标志的肿瘤区域中的自旋密度，PO2图和PO2直方图相似。还使用OX071和OX063在无胸腺小鼠上进行了健康的肾脏成像。与OX063相比，OX071的血氧饱和度显示出肾脏中更均匀的PO2曲线，这表明OX071适用于较高的PO2范围内组织中的血氧饱和度。 evofosfamide功效中的肿瘤微环境决定因素：胰腺导管腺癌（PDAC）形成低血管肿瘤和低氧肿瘤，这些肿瘤难以通过当前的化疗方案治疗。吉西他滨（GEM）通常用作PDAC的一线治疗，但在肿瘤内部具有化学耐药性和穿透性问题。 Evofosfamide是一种活化前药的一种缺氧，尽管尚未确定每种药物的机制，但已被证明与GEM相结合。我们使用了来自两种细胞系（MIA PACA-2和SU 86.86）的两种小鼠异种移植物，具有不同的肿瘤微环境特性，以探测每种药物对彼此的作用。 GEM治疗增加了SU.86.86异种移植的小鼠的生存时间（HR = 0.35，95％CI = 0.13至0.90 P = 0.03），但对MIA PACA-2小鼠没有影响（HR = 0.91，95％CI = 0.37至0.37至2.25至2.25，P = 0.84）。相反，Evofosfamide对SU86.86小鼠没有影响，并且没有提高生存时间至统计学意义（HR = 0.57，95％CI = 0.23至1.42，P = 0.22）。在最初灌注不良的MIA PACA-2肿瘤中，电子顺磁共振（EPR）成像表明，用GEM处理时，氧合发生变化，为通过GEM激活Evofosfamide提供了直接的机制，以及Evofosfamide和Gem组合的有效性。 su86.86中的其他治疗量增强了其他治疗的毒性，但在Miapaca-2中却没有。在SU86.86的组合处理中，双链DNA病变的修复得到了增强，但没有增强MIA PACA-2。已经提出了Evofosfamide和Gem之间协同作用的可能机制。 GEM和Evofosfamide之间的协同作用似乎源于GEM对肿瘤脉管系统的影响的双重作用以及对同源重组DNA修复过程的GEM抑制。每种途径的相对重要性取决于肿瘤微环境，值得进一步研究。缺氧激活的前药evofosfamide改善了肿瘤的氧合。肿瘤的区域低。氧气水平称为低氧区域，这些区域对放射疗法和化学疗法具有抗性。缺氧活化的前药（如evofosfamide）是开发出来特异性杀死缺氧区域的细胞的。在低氧肿瘤微环境中，强烈降低的氧化还原状态将Evofosfamide（TH-302）转化为减少形式，并释放出细胞毒性的溴 - 异磷酰胺（BR-IPM）部分。因此，该药物优先攻击其他标准抗癌治疗（例如化学疗法和放射疗法）的肿瘤中缺氧区域。已经在临床前和临床环境中提出并测试了与Evofosfamide的各种组合疗法。然而，尚未完全理解evofosfamide单药治疗对肿瘤缺氧的治疗效果，部分原因是缺乏评估体内肿瘤PO2的定量方法。在这里，我们使用EPR的定量PO2成像来评估使用两种胰腺导管腺癌异种移植模型，以响应Evofosfamide处理，以评估肿瘤缺氧的变化。 MIA PACA-2肿瘤对Evofosfamide和SU.86.86肿瘤反应。 EPR成像显示，在低氧MIA PACA-2肿瘤中，EPR成像在全球范围内改善了全球范围，这与偶膜甲苯性唑低氧染色所获得的离体结果一致，并且显然与DCE MRI观察到的KTRANS的减少相反。观察结果是，evofosfamide不仅杀死肿瘤的低氧区域，而且还可以改善残留肿瘤区域的氧合，为使用辐射和抗增殖剂后的Evofofosfamide结合疗法提供了一种理由，以改善结果。