Huang Wei, Cao Min, Wu Yanfei, Zhang You, An Shuxian, Pan Xinbing, Zhou Xinyuan, Shao Hongda, Guan Yihui, Huang Gang, Gelardi Fabrizia, Chiti Arturo, Xie Fang, Liu Jianjun, Wei Weijun
Department of Nuclear Medicine, Institute of Clinical Nuclear Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.
Department of Thoracic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
J Nucl Med. 2024 Dec 3;65(12):1904-1910. doi: 10.2967/jnumed.124.268751.
Immuno-PET/CT imaging, a branch of molecular imaging, can noninvasively and specifically visualize biomarker expression across the body. Trophoblast cell surface antigen 2 (Trop2) is a pan-cancer biomarker and plays a crucial role in tumorigenesis through multiple signaling pathways. The study aims to develop and translate novel Trop2 single-domain antibody (sdAb) tracers for clinical use. Two sdAbs (i.e., His-tagged T4 and His-tag-free RT4) are recombinantly expressed in Chinese hamster ovary cells. The purities and binding kinetics are determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, high-performance liquid chromatography, and surface plasmon resonance assays. The AlF restrained complexing agent (RESCA) method is applied to develop F-labeled sdAb tracers ([F]AlF-RESCA-T4 and [F]AlF-RESCA-RT4), followed by thorough preclinical imaging and blocking studies on tumor-bearing mice and a pilot clinical trial evaluating the clinical imaging safety and feasibility of [F]AlF-RESCA-T4 immuno-PET/CT. [F]AlF-RESCA-T4 and [F]AlF-RESCA-RT4 possess high radiochemical purities. Preclinical imaging in the T3M-4 tumor model revealed prominent uptake (percentage injected dose/g) of [F]AlF-RESCA-T4 (11.13 ± 1.53, = 4) and [F]AlF-RESCA-RT4 (8.83 ± 1.22, = 4), which were significantly reduced by coinjection of unlabeled T4 and RT4 in blocking studies. The His-tag removal strategy further optimized the probe's in vivo pharmacokinetics and reduced renal radioactivity accumulation without significantly decreasing tumor uptake. In a pilot clinical trial, [F]AlF-RESCA-T4 immuno-PET/CT showed promising potency in annotating Trop2 expression and differentiating tumors from inflammatory diseases such as tuberculosis. [F]AlF-RESCA-T4 and [F]AlF-RESCA-RT4 can specifically annotate Trop2 expression. Clinical [F]AlF-RESCA-T4 immuno-PET/CT imaging can screen patients for Trop2-targeted therapies and differentiate lung inflammation from cancer.
免疫正电子发射断层扫描/计算机断层扫描（Immuno-PET/CT）成像作为分子成像的一个分支，能够非侵入性且特异性地显示全身生物标志物的表达情况。滋养层细胞表面抗原2（Trop2）是一种泛癌生物标志物，通过多种信号通路在肿瘤发生过程中发挥关键作用。本研究旨在开发并转化新型Trop2单域抗体（sdAb）示踪剂以供临床使用。两种sdAb（即带有组氨酸标签的T4和无组氨酸标签的RT4）在中国仓鼠卵巢细胞中进行重组表达。通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳、高效液相色谱和表面等离子体共振分析来测定其纯度和结合动力学。应用铝氟抑制络合剂（RESCA）方法开发氟标记的sdAb示踪剂（[F]AlF-RESCA-T4和[F]AlF-RESCA-RT4），随后对荷瘤小鼠进行全面的临床前成像和阻断研究，并开展一项评估[F]AlF-RESCA-T4免疫正电子发射断层扫描/计算机断层扫描临床成像安全性和可行性的临床试验。[F]AlF-RESCA-T4和[F]AlF-RESCA-RT4具有较高的放射化学纯度。在T3M-4肿瘤模型中的临床前成像显示，[F]AlF-RESCA-T4（11.13±1.53，n = 4）和[F]AlF-RESCA-RT4（8.83±1.22，n = 4）有显著摄取（注射剂量/克百分比），在阻断研究中，通过共同注射未标记的T4和RT4，摄取量显著降低。去除组氨酸标签的策略进一步优化了探针的体内药代动力学，并减少了肾脏放射性积累，同时并未显著降低肿瘤摄取。在一项临床试验中，[F]AlF-RESCA-T4免疫正电子发射断层扫描/计算机断层扫描在标注Trop2表达以及区分肿瘤与结核病等炎症性疾病方面显示出有前景的效能。[F]AlF-RESCA-T4和[F]AlF-RESCA-RT4能够特异性地标注Trop2表达。临床[F]AlF-RESCA-T4免疫正电子发射断层扫描/计算机断层扫描成像可用于筛选适合Trop2靶向治疗的患者，并区分肺部炎症与癌症。
