Granzyme B is an attractive target as a biomarker for contributing to improve the treatment with immune checkpoint inhibitor (ICI). In this study, we designed novel ¹¹¹In-labeled granzyme B-targeting single-photon emission computed tomography (SPECT) imaging probes, [¹¹¹In]IDT and [¹¹¹In]IDAT. Nonradioactive In-labeled granzyme B-targeting compounds ([^natIn]IDT, [^natIn]IDAT) showed the affinity for recombinant mouse granzyme B. [¹¹¹In]IDT and [¹¹¹In]IDAT were obtained with moderate radiochemical yield and high stability in mouse plasma (>95%). In a biodistribution experiment using tumor-bearing mice, [¹¹¹In]IDT and [¹¹¹In]IDAT showed moderate accumulation in tumor. Ex vivo autoradiography (ARG) indicated that the accumulation of radioactivity in tumor was correlated to expression of granzyme B confirmed by the immunohistochemical staining. These results indicated that [¹¹¹In]IDT and [¹¹¹In]IDAT showed the basic properties as granzyme B-targeting SPECT probes.

中文翻译：

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111In 标记的四肽类化合物作为单光子发射计算机断层扫描成像探针靶向颗粒酶 B 的合成和评价

粒酶 B 是一个有吸引力的生物标志物靶标，有助于改善免疫检查点抑制剂 (ICI) 的治疗。在本研究中，我们设计了新型¹¹¹ In 标记颗粒酶 B 靶向单光子发射计算机断层扫描 (SPECT) 成像探针、[ ¹¹¹ In]IDT 和 [ ¹¹¹ In]IDAT。非放射性 In 标记的颗粒酶 B 靶向化合物（[ ^nat In]IDT、[ ^nat In]IDAT）显示出对重组小鼠颗粒酶 B 的亲和力。[ ¹¹¹ In]IDT 和 [ ¹¹¹ In]IDAT 具有中等的放射化学产率和较高的产率。小鼠血浆中的稳定性（>95%）。在使用荷瘤小鼠进行的生物分布实验中，[ ¹¹¹ In]IDT 和[ ¹¹¹ In]IDAT 在肿瘤中显示出中等积累。离体放射自显影(ARG)表明肿瘤中放射性的积累与免疫组织化学染色证实的颗粒酶B的表达相关。这些结果表明[ ¹¹¹ In]IDT和[ ¹¹¹ In]IDAT显示出作为粒酶B靶向SPECT探针的基本特性。