构建并初步评估一种针对 PD-L1 和 PD-L2 的 I 型放射性标记双特异性抗体。
Construction and preclinical evaluation of a I-labelled bispecific antibody targeting PD-L1 and PD-L2.
机构信息
Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute, Peking University, No. 52 Fu-Cheng Rd, Beijing, 100142, People's Republic of China.
Guizhou University School of Medicine, Guiyang, Guizhou, 550025, People's Republic of China.
出版信息
Eur J Nucl Med Mol Imaging. 2024 Dec;52(1):36-47. doi: 10.1007/s00259-024-06886-5. Epub 2024 Aug 19.
PURPOSE
NB12 is a bispecific antibody that consists of two anti-programmed cell death-ligand 1 (PD-L1) nanobodies and two anti-programmed cell death-ligand 2 (PD-L2) nanobodies. The aim of this study was to design a novel tracer, [I]I-NB12, targeting PD-L1/2 and perform preclinical evaluations to dynamically monitor PD-L1/2 expression for determining cancer patient responsiveness to ICI therapy.
METHODS
NB12 was labelled with the radionuclide I at room temperature (RT). An in vitro binding assay was performed to assess the affinity of [I]I-NB12 for PD-L1 and PD-L2. Cellular uptake, pharmacokinetic, and biodistribution experiments were performed to evaluate the biological properties. Micro-PET/CT imaging with [I]I-NB12 was conducted at different time points. Immunohistochemical and haematoxylin and eosin (HE) staining experiments were carried out using tumour tissues. Routine blood, biochemical indices and major organ pathology were used to evaluate the biosafety of the tracers.
RESULTS
The radiochemical yield of [I]I-NB12 was 84.62 ± 3.90%, and the radiochemical purity (RCP) was greater than 99%. [I]I-NB12 had a high affinity for the PD-L1 (Kd = 19.82 nM) and PD-L2 (Kd = 2.93 nM). Cellular uptake experiments confirmed that the uptake of [I]I-NB12 by A549-PDL1/2 cells was greater than that by A549 cells. The half-lives of the distribution phase and elimination phase were 0.26 h and 4.08 h, respectively. Micro-PET/CT showed significant [I]I-NB12 uptake in the tumour region of A549-PDL1/2 tumour-bearing mice compared with A549 tumour-bearing mice 24 h postinjection. Immunohistochemical and HE staining experiments confirmed that tumour-bearing mice was successfully constructed.
CONCLUSION
We constructed a bispecific antibody that targets PD-L1 and PD-L2, namely, [I]I-NB12. Biological evaluation revealed its specificity and affinity for PD-L1/2, and micro-PET/CT confirmed the feasibility of visualizing tumour PD-L1/2 in vivo. Using [I]I-NB12 may be a promising strategy for identifying cancer patients that can potentially benefit from ICI therapy.
目的
NB12 是一种双特异性抗体，由两个抗程序性死亡配体 1（PD-L1）纳米体和两个抗程序性死亡配体 2（PD-L2）纳米体组成。本研究的目的是设计一种新型示踪剂[I]I-NB12，用于靶向 PD-L1/2，并进行临床前评估，以动态监测 PD-L1/2 的表达，从而确定癌症患者对 ICI 治疗的反应。
方法
室温下将 NB12 标记放射性核素 I。进行体外结合实验以评估[I]I-NB12 对 PD-L1 和 PD-L2 的亲和力。进行细胞摄取、药代动力学和生物分布实验以评估其生物学特性。使用[I]I-NB12 进行微 PET/CT 成像。在不同时间点进行肿瘤组织的免疫组化和苏木精和伊红（HE）染色实验。使用肿瘤组织进行常规血液、生化指标和主要器官病理检查，以评估示踪剂的生物安全性。
结果
[I]I-NB12 的放射化学产率为 84.62±3.90%，放射化学纯度（RCP）大于 99%。[I]I-NB12 对 PD-L1（Kd=19.82 nM）和 PD-L2（Kd=2.93 nM）具有高亲和力。细胞摄取实验证实，A549-PDL1/2 细胞对[I]I-NB12 的摄取大于 A549 细胞。分布相和消除相的半衰期分别为 0.26 h 和 4.08 h。微 PET/CT 显示，与 A549 荷瘤小鼠相比，注射后 24 h，A549-PDL1/2 荷瘤小鼠肿瘤部位有明显的[I]I-NB12 摄取。免疫组化和 HE 染色实验证实成功构建了荷瘤小鼠。
结论
我们构建了一种靶向 PD-L1 和 PD-L2 的双特异性抗体，即[I]I-NB12。生物学评价表明其对 PD-L1/2 具有特异性和亲和力，微 PET/CT 证实了体内可视化肿瘤 PD-L1/2 的可行性。使用[I]I-NB12 可能是一种有前途的策略，用于识别可能从 ICI 治疗中获益的癌症患者。
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