新型分子探针^(89)Zr-DFO-G4C2监测PD-1表达水平的临床前研究  

Preclinical study of a novel molecular probe 89Zr DFO-G4C2 for monitoring PD-1 expression levels

作　　者：朱怡蓉 孔维唯 尤嘉熙[1] 倪凯茹[1] 张兵 刘增礼[1] 石怡珍[1] 洪智慧[1] Zhu Yirong;Kong Weiwei;You Jiaxi;Ni Kairu;Zhang Bing;Liu Zengli;Shi Yizhen;Hong Zhihui(Department of Nuclear Medicine,the Second Affiliated Hospital of Soochow University,Suzhou 215004,China)

机构地区：[1]苏州大学附属第二医院核医学科,苏州215004

出　　处：《中华核医学与分子影像杂志》2024年第10期603-608,共6页Chinese Journal of Nuclear Medicine and Molecular Imaging

基　　金：上海市分子影像学重点实验室一般项目(KFKT-2023-23);放射医学与辐射防护国家重点实验室资助项目(GZK1202240);国家卫生健康委核医学重点实验室、江苏省分子核医学重点实验室开放课题(KF202205);苏州大学附属第二医院科研预研基金项目(SDFEYJC2113)。

摘　　要：目的设计合成靶向程序性细胞死亡受体1(PD-1)新型分子探针^(89)Zr-去铁胺(DFO)-G4C2,探究其在荷瘤小鼠体内的生物分布并行microPET/CT显像。方法DFO偶联抗PD-1单克隆抗体G4C2合成DFO-G4C2,采用流式细胞术和表面等离子共振技术评估DFO-G4C2的亲和力及结合特异性。进行^(89)Zr标记,得到^(89)Zr-DFO-G4C2,分析其标记率及体外稳定性。建立PD-1表达阳性的CT26结直肠癌荷瘤小鼠模型,通过microPET/CT显像及体内生物分布探讨^(89)Zr-DFO-G4C2的潜在临床应用价值,并在4T1乳腺癌模型中验证该分子探针在不同肿瘤模型中显像效果。采用两独立样本t检验分析数据。结果DFO-G4C2亲和力常数KD值为(0.55±0.02)μmol/L,与小鼠PD-1蛋白的结合率为(61.82±8.49)%。^(89)Zr-DFO-G4C2的标记率为(98.76±0.51)%,在溶媒和人血清中放置144 h的标记率分别为(93.07±2.16)%和(83.42±3.21)%。CT26荷瘤小鼠microPET/CT显像示肿瘤组织有明显^(89)Zr-DFO-G4C2摄取,在注射后72 h肿瘤摄取值为(10.47±0.34)每克组织百分注射剂量率(%ID/g),而注射过量未标记抗体的阻断组的肿瘤摄取值为(6.26±1.03)%ID/g,明显低于实验组肿瘤摄取值(t=6.67,P=0.003)。体内生物分布结果与microPET/CT显像基本一致。4T1乳腺癌荷瘤小鼠模型microPET/CT显像结果与CT26模型相似。结论基于^(89)Zr-DFO-G4C2分子探针的免疫PET显像可以无创、可视化地评估肿瘤微环境中PD-1表达水平,有望成为一种用于PD-1抑制剂免疫治疗监测的分子影像学新技术。ObjectiveTo design and synthesize^(89)Zr-deferoxamine(DFO)-G4C2,a novel molecular probe targeting programmed cell death receptor 1(PD-1),and evaluate its in vivo biodistribution and microPET/CT imaging characteristics in tumor-bearing mice.MethodsDFO-G4C2 was prepared by coupling DFO with G4C2,a monoclonal antibody targeting PD-1.The affinity and binding specificity of this amalgamation were subsequently assessed through the implementation of flow cytometry and surface plasmon resonance techniques.The molecular probe^(89)Zr-DFO-G4C2 was achieved by labeling DFO-G4C2 with the radioisotope^(89)Zr,and the labeling efficiency and in vitro stability of^(89)Zr-DFO-G4C2 were determined.Mouse models laden with CT26 colorectal cancer cells expressing PD-1 were established,followed by in vivo biodistribution and microPET/CT imaging studies,to explore the potential clinical value of^(89)Zr-DFO-G4C2.Additionally,the validity of this molecular probe was verified in 4T1 breast cancer models,affirming its efficacy as an imaging tool across different tumor models.Independent-sample t test was used to analyze the data.ResultsDFO-G4C2 exhibited an affinity constant K D of(0.55±0.02)μmol/L,indicating a strong binding affinity.The binding rate to mouse PD-1 protein was determined to be(61.82±8.49)%.The labeling rate of^(89)Zr-DFO-G4C2 reached a high level of(98.76±0.51)%.Furthermore,the labeling rates in lysate and human serum after 144 h were measured to be(93.07±2.16)%and(83.42±3.21)%,respectively.MicroPET/CT imaging of CT26 tumor-bearing mice injected with^(89)Zr-DFO-G4C2 showcased pronounced radioactivity uptake in the tumor tissue.At 72 h post-injection,the tumor uptake value reached(10.47±0.34)percentage activity of injection dose per gram of tissue(%ID/g).The tumor uptake observed in the blocked experimental group,wherein an excess of unlabeled antibody was administered,was significantly lower at(6.26±1.03)%ID/g in comparison to the non-blocked group(t=6.67,P=0.003).The in vivo biodistribution results were consistent

关 键 词：程序性细胞死亡受体1 同位素标记 锆 结直肠肿瘤 乳腺肿瘤 正电子发射断层显像术 小鼠 

分 类 号：R730.44[医药卫生—肿瘤]