目的:跨膜糖蛋白滋养层细胞表面抗原2(Trop2)的高表达与实体瘤的进展密切相关,包括胰腺癌和胃癌.我们的研究旨在构建Trop2特异性免疫正电子发射断层扫描(免疫PET)探针,并评估临床前胰腺癌和胃癌模型的诊断能力。
方法:通过单细胞测序和组织芯片(TMA)上的免疫组织化学检测Trop2在胰腺癌中的表达。流式细胞术用于筛选Trop2在胰腺癌细胞系中的表达。两个纳米体(即,开发了靶向Trop2的RTD98和RTD01)并用镓68(68Ga,T1/2=1.1h)构建免疫PET成像探针。在表达不同Trop2的细胞来源的胰腺癌和患者来源的胃癌模型中研究了这些药物。
结果:单细胞测序结果显示Trop2在胰腺导管细胞和腺泡细胞中高表达,胰腺癌TMA的免疫组织化学染色显示Trop2在癌组织中的表达明显高于癌旁组织。利用[68Ga]Ga-NOTA-RTD98的免疫PET可以清楚地描绘皮下肿瘤,在细胞源性胰腺癌模型和患者源性胃癌模型中,优于使用[18F]-FDG或非特异性探针[68Ga]Ga-NOTA-RTD161的成像。进一步制备了另一种具有改善的靶向Trop2的药代动力学的探针[68Ga]Ga-NOTA-RTD01,并在临床前胰腺癌模型中显示出有利的诊断能力。
结论:在工作中,我们报道了两种靶向人Trop2的纳米抗体示踪剂,这些示踪剂可以通过无创地显示靶标的表达动力学来促进Trop2靶向治疗的更好使用.
OBJECTIVE: The high expression of the transmembrane glycoprotein trophoblast cell-surface antigen 2 (Trop2) was strongly associated with the progression of solid tumors, including pancreatic and gastric cancers. Our study aimed to construct Trop2-specific immuno-positron emission tomography (immunoPET) probes and assess the diagnostic abilities in preclinical pancreatic and gastric cancer models.
METHODS: The expression of Trop2 in pancreatic cancer was determined by single-cell sequencing and immunohistochemistry on tissue microarray (TMA). Flow cytometry was used to screen the expression of Trop2 in pancreatic cancer cell lines. Two nanobodies (i.e., RTD98 and RTD01) targeting Trop2 were developed and labeled with gallium-68 (68Ga, T1/2 = 1.1 h) to construct immunoPET imaging probes. The agents were researched in cell-derived pancreatic and patient-derived gastric cancer models expressing varying Trop2.
RESULTS: Single-cell sequencing results showed high expression of Trop2 in pancreatic ductal cells as well as acinar cells and immunohistochemical staining of TMA from pancreatic cancers showed significantly higher expression of Trop2 in cancerous than in paracancerous tissues. ImmunoPET utilizing [68Ga]Ga-NOTA-RTD98 could clearly delineate subcutaneous tumors, both in cell-derived pancreatic cancer models and patient-derived gastric cancer models, superior to imaging using [18F]-FDG or a non-specific probe [68Ga]Ga-NOTA-RTD161. Another probe with improved pharmacokinetics targeting Trop2, [68Ga]Ga-NOTA-RTD01, was further prepared and showed advantageous diagnostic capabilities in preclinical pancreatic cancer models.
CONCLUSIONS: In the work, we reported two nanobody tracers targeting human Trop2 which may facilitate better use of Trop2-targeted therapeutics by noninvasively displaying expression dynamics of the target.