Non-invasive molecular MR spectroscopic imaging of histone deacetylase activity

描述（由申请人提供）：对癌症潜在机制的更深入理解导致开发针对个体患者的新型靶向治疗。然而，对这些疗法的反应通常导致肿瘤停滞。因此，使用间接或侵入性指标确定生物学相关的药物剂量和对治疗的早期反应。因此，迫切需要一种非侵入性的方法来评估药物递送和靶部位的分子反应。我们的长期目标是开发和实施基于非侵入性磁共振（MR）的分子成像方法，可以检测新型靶向癌症治疗的作用和反应。本申请的目的是临床前测试和实施组蛋白脱乙酰酶（HDAC）活性的直接、非侵入性、19 F MR光谱标记物，作为体内对HDAC抑制剂（HDACI）的分子反应的特异性指标。次要目标是鉴定与HDAC抑制相关的下游代谢生物标志物。我们建议测试氟化赖氨酸衍生物Boc-Lys-TFA-OH（BIT）。我们已经证实BLT在体外被HDAC切割。从细胞提取物的MR光谱（MRS）研究中，我们还确定了HDAC处理后细胞内BLT水平显著更高，并且与HDAC抑制相关。磷酸胆碱（PC）和总胆碱（tCho）水平在处理的细胞提取物中也更高。因此，我们认为较高的细胞BLT水平与较高的tCho水平可以作为HDAC抑制的分子标志物。为了在体内实现这一点，我们提出：具体目标1。确认BLT作为HDAC抑制的MRS药效学标志物。我们将使用灌注的活细胞来模拟细胞内和细胞外BLT信号无法区分的体内情况。BLT水平将通过高分辨率MRS监测，并与对照和HDACI处理的细胞中的HDAC活性相关。具体目标2。使用磁共振光谱成像监测HDAC在体内肿瘤中的抑制。我们将使用局部19 F光谱成像来监测BLT水平，并使用1H光谱成像来测量对照和治疗肿瘤中的tCho水平。MR数据将与HDAC活性、下游信号传导和肿瘤大小相关。这种方法的未来翻译到临床将允许无创纵向定位监测HDACI治疗。通过非侵入性地和在靶部位告知药物递送和对治疗的分子反应，该技术因此有望改善患者护理。本案无关HDACIs是目前在临床试验中具有有希望结果的新型抗癌剂。然而，适当的药物剂量和早期反应往往难以评估。这项工作的目标是开发一种非侵入性的MRS为基础的成像方法，用于检测反应HDACIs在目标网站。因此，将这种方法引入临床使用将转化为改善患者护理。

DESCRIPTION (provided by applicant): Greater understanding of the underlying mechanisms of cancer is leading to development of novel targeted therapies tailored to individual patients. However, response to these therapies often results in tumor stasis. Consequently, the biologically relevant drug dose and early response to treatment are determined using indirect or invasive indicators. A noninvasive method of assessing drug delivery and molecular response at the target site is therefore critically needed. Our long-term goal is to develop and implement noninvasive magnetic resonance (MR)-based molecular imaging methods that can detect the action of and response to novel targeted cancer treatments. The goal of this application is to pre-clinically test and implement a direct, noninvasive, 19F MR spectroscopic marker of histone deacetylase (HDAC) activity, as a specific indicator of molecular response to HDAC inhibitors (HDACIs) in vivo. A secondary goal is to identify downstream metabolic biomarkers associated with HDAC inhibition. We propose to test the fluorinated lysine derivative Boc-Lys-TFA-OH (BIT). We have confirmed that BLT is cleaved in vitro by HDAC. From MR spectroscopy (MRS) studies of cell extracts we have also determined that intracellular BLT levels are significantly higher following HDACI-treatment and correlate with HDAC inhibition. Phosphocholine (PC) and total choline (tCho) levels are also higher in treated cell extracts. We therefore suggest that higher cellular BLT levels together with higher tCho levels can serve as molecular markers of HDAC inhibition. To implement this in vivo we propose: Specific Aim 1. To confirm BLT as an MRS pharmacodynamic marker of HDAC inhibition. We will use perfused live cells to model the in vivo situation in which intracellular and extracellular BLT signals are indistinguishable. BLT levels will be monitored by high resolution MRS and correlated with HDAC activity in control and HDACI-treated cells. Specific Aim 2. To monitor HDAC inhibition in tumors in vivo using magnetic resonance spectroscopic imaging. We will use localized 19F spectroscopic imaging to monitor BLT levels and 1H spectroscopic imaging to measure tCho levels in control and treated tumors. The MR data will be correlated with HDAC activity, downstream signaling and tumor size. Future translation of this method to the clinic will allow for noninvasive longitudinal localized monitoring of HDACI-treatment. By informing on drug delivery and molecular response to treatment, noninvasively and at the target site, this technique therefore promises to improve patient care. Relevance. HDACIs are novel anti-cancer agents currently in clinical trials with promising results. However, appropriate drug dose and early response are often difficult to assess. The goal of this work is to develop a noninvasive MRS-based imaging method for detecting response to HDACIs at the target site. The introduction of this method into clinical use will therefore translate into improved patient care.