Samkoe Kimberley S, Tichauer Kenneth M, Gunn Jason R, Wells Wendy A, Hasan Tayyaba, Pogue Brian W
Department of Surgery, Geisel School of Medicine at Dartmouth College, Lebanon, New Hampshire. Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire.
Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Illinois.
Cancer Res. 2014 Dec 15;74(24):7465-74. doi: 10.1158/0008-5472.CAN-14-0141. Epub 2014 Oct 24.
As receptor-targeted therapeutics become increasingly used in clinical oncology, the ability to quantify protein expression and pharmacokinetics in vivo is imperative to ensure successful individualized treatment plans. Current standards for receptor analysis are performed on extracted tissues. These measurements are static and often physiologically irrelevant; therefore, only a partial picture of available receptors for drug targeting in vivo is provided. Until recently, in vivo measurements were limited by the inability to separate delivery, binding, and retention effects, but this can be circumvented by a dual-tracer approach for referencing the detected signal. We hypothesized that in vivo receptor concentration imaging (RCI) would be superior to ex vivo immunohistochemistry (IHC). Using multiple xenograft tumor models with varying EGFR expression, we determined the EGFR concentration in each model using a novel targeted agent (anti-EGFR affibody-IRDye800CW conjugate) along with a simultaneously delivered reference agent (control affibody-IRDye680RD conjugate). The RCI-calculated in vivo receptor concentration was strongly correlated with ex vivo pathologist-scored IHC and computer-quantified ex vivo immunofluorescence. In contrast, no correlation was observed with ex vivo Western blot analysis or in vitro flow-cytometry assays. Overall, our results argue that in vivo RCI provides a robust measure of receptor expression equivalent to ex vivo immunostaining, with implications for use in noninvasive monitoring of therapy or therapeutic guidance during surgery.
随着受体靶向疗法在临床肿瘤学中的应用日益广泛，体内定量蛋白质表达和药代动力学的能力对于确保成功的个体化治疗方案至关重要。目前受体分析的标准是在提取的组织上进行的。这些测量是静态的，而且往往与生理情况无关；因此，只能提供体内药物靶向可用受体的部分情况。直到最近，体内测量还受到无法区分递送、结合和保留效应的限制，但这可以通过一种双示踪剂方法来规避，该方法用于参考检测到的信号。我们假设体内受体浓度成像（RCI）将优于体外免疫组织化学（IHC）。使用具有不同表皮生长因子受体（EGFR）表达的多种异种移植肿瘤模型，我们使用一种新型靶向剂（抗EGFR亲合体-IRDye800CW偶联物）以及同时递送的参考剂（对照亲合体-IRDye680RD偶联物）来确定每个模型中的EGFR浓度。RCI计算的体内受体浓度与体外病理学家评分的IHC以及计算机定量的体外免疫荧光密切相关。相比之下，未观察到与体外蛋白质印迹分析或体外流式细胞术检测有相关性。总体而言，我们的结果表明，体内RCI提供了一种与体外免疫染色相当的受体表达的可靠测量方法，对在治疗的无创监测或手术期间的治疗指导中的应用具有启示意义。
