Basic Science Investigation
Site-specific labelling and biological evaluation of PD-L1 targeted single-domain antibody
Chen Yinfei, Chen Panpan, Zhu Shiyu, Liang Beibei, Xie Minhao, Lin Jianguo, Qiu Ling
Published 2022-12-25
Cite as Chin J Nucl Med Mol Imaging, 2022, 42(12): 744-750. DOI: 10.3760/cma.j.cn321828-20220509-00151
Abstract
ObjectiveTo synthesize a novel site-specifically labelled probe 68Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)-Cys-Asp-Val (CDV)-Nb109 and explore its potential for detection of the programmed cell death ligand 1 (PD-L1) expression level in different tumors.
MethodsFirstly, CDV was inserted into the tail of the sequence of Nb109 by genetic engineering. Then the precursor DOTA-CDV-Nb109 was prepared by mixing the maleimide-DOTA and the single-domain antibody CDV-Nb109 (amount of substance ratio 1∶1) via the maleimide-cysteine site-specific coupling strategy. Subsequently, the DOTA-CDV-Nb109 was labeled with 68Ga and purified by PD-10 column. Human melanoma A375, human PD-L1 transfected melanoma A375-hPD-L1 and human glioma U87 tumor-bearing mice models were established, and the diagnostic value of 68Ga-DOTA-CDV-Nb109 was evaluated by stability assay, cellular uptake, and microPET imaging. One-way analysis of variance and the least significant difference t test were used to analyze the data.
ResultsThe probe 68Ga-DOTA-CDV-Nb109 was obtained with the radiochemical yield of (69.79±4.69)%, radiochemical purity more than 97%, and molar activity of (12.85±1.51) GBq/μmol. 68Ga-DOTA-CDV-Nb109 had strong binding affinity for A375-hPD-L1 with the dissociation constant (Kd) of (66.43±17.89) nmol/L. The uptake of 68Ga-DOTA-CDV-Nb109 in A375-hPD-L1 and U87 cells were (3.17±0.15) percentage of the added radioactivity dose (%AD) and (2.08±0.03) %AD respectively, which were significantly higher than that in A375 cells ((1.21±0.14) %AD; F=82.87, t values: 15.23, 9.98, P values: <0.001, 0.003). The tumor uptake of the probe in A375-hPD-L1 ((5.21±0.35) percentage of injected dose per ml (%ID/ml)) and U87 tumor-bearing mice ((3.44±0.69) %ID/ml) were significantly higher than that in A375 tumor-bearing mice ((2.17±0.36) %ID/ml; F=249.72, t values: 35.70, 3.43, both P<0.001).
ConclusionThe site-specifically labelled probe 68Ga-DOTA-CDV-Nb109, which can non-invasively and dynamically monitor the change of PD-L1 expression level in different tumors and help screen patients who can benefit from PD-L1 immune checkpoint blocking therapy, is successfully synthesized with high radiochemical purity.
Key words:
Programmed cell death 1 receptor; Single-domain antibodies; Isotope labeling; Gallium radioisotopes; Tumor cells, cultured; Positron-emission tomography; Mice, nude
Contributor Information
Chen Yinfei
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Chen Panpan
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Zhu Shiyu
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Liang Beibei
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Xie Minhao
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Lin Jianguo
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
Qiu Ling
NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
