124I-Labeled Monoclonal Antibody and Fragment for the Noninvasive Evaluation of Tumor PD-L1 Expression In Vivo
124I-Labeled Monoclonal Antibody and Fragment for the Noninvasive Evaluation of Tumor PD-L1 Expression In Vivo
复制标题
124I 标记的单克隆抗体和片段用于体内肿瘤 PD-L1 表达的无创评估
DOI：
10.1021/acs.molpharmaceut.2c00084
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发表时间：
2022-03-04
影响因子：
4.9
通讯作者：
Cheng, Dengfeng
中科院分区：
文献类型：
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作者：
Cheng, Yuan;Shi, Dai;Cheng, Dengfeng
肺癌是一种高度异质性的癌症，大致分为小细胞肺癌和非小细胞肺癌（SCLC或NSCLC）。在所有NSCLC患者中，估计有50%-60%为程序性细胞死亡配体1（PD-L1）阳性，抗PD-1/PD-L1治疗在晚期NSCLC中已显示出临床应用前景。为了避免不必要的不良反应，并为最合适的患者人群提供抗PD-1/PD-L1治疗，必须准确、真实的评估准备接受治疗的患者的PD-L1表达。在这项研究中，我们使用I-124标记的durvalumab（Durva）的F（ab '）（2）片段非侵入性地评估NSCLC异种移植物中的PD-L1表达，并在生物分布和剂量测定方面与I-124标记的完整抗体进行比较。目的是开发一种性能更好的用于PD-L1免疫PET成像的核素标记分子探针。用IdeS蛋白酶切割后，用I-124标记Durva的F（ab '）（2）片段.放射性配体显示出高的放射化学纯度（>96%）和突出的稳定性。对两种选择的NSCLC细胞系进行Western印迹、定量实时聚合酶链反应和流式细胞术，以测量体外PD-L1表达。H460细胞在蛋白质水平和mRNA水平上的PD-L1表达均比A549细胞高得多。在随后的细胞结合实验和结合特异性测定中，标记的放射性配体显示出对高PD-L1表达细胞的良好亲和力，并且可以被过量的未标记的完整Durva阻断。生物分布和正电子发射断层扫描（PET）结果显示，I-124-Durva-F（ab '）（2）的肿瘤摄取峰值与I-124-Durva接近，但更早（I-124-Durva-F（ab '）（2）在12小时时为5.29 +/-0.42%ID/g，而I-124-Durva在48小时时为5.18 +/-0.73%ID/g）。与I-124-Durva相比，观察到I-124-Durva-F（ab '）的血液清除加快（2）。更快的血液清除允许更高的肿瘤与背景比，这反映在图像上的对比度。早在注射I-124-Durva-F（ab '）（2）后4小时，H460肿瘤就显示出极好的对比度，而对于I-124-Durva，异种移植物直到注射后24小时才能清楚区分。有趣的是，与其他金属同位素标记的PD-L1抗体相比，I-124-Durva-F（ab '）（2）在骨、肝、脾等中显示出较低的积累，这将有利于转移检测。加速血液清除的另一个好处是减少辐射剂量。根据OLINDA/EXM的结果，I-124-Durva的全身有效剂量是I-124-Durva-F（ab '）（2）的4.25倍（186 mu Sv/MBq vs 43.8 mu Sv/MBq）。所有这些数据表明，I-124-Durva-F（ab '）（2）是一种有前途的免疫PET示踪剂，可用于评估NSCLC模型中的体内PD-L1水平，并有望在未来的临床应用中取得成功。
Lung cancer is a highly heterogeneous cancer and is divided broadly into small and nonsmall cell lung cancer (SCLC or NSCLC). In all NSCLC patients, it is estimated that 50%-60% are programmed cell death ligand 1 (PD-L1) positive, and anti-PD-1/PD-L1 therapies have shown their clinical application prospects in advanced NSCLC. To avoid unnecessary adverse effects and provide anti-PD-1/PD-L1 therapy to the most appropriate patient population, the PD-L1 expression in patients preparing for treatment must be evaluated accurately and in real time. In this study, we noninvasively evaluate the PD-L1 expression in an NSCLC xenograft using I-124-labeled F(ab ')(2) fragments of durvalumab (Durva) and compared it with the I-124-labeled intact antibody in terms of the biodistribution and dosimetry. The aim is to develop a nuclide labeled molecular probe with better performance for PD-L1 immunoPET imaging. After cleaving using IdeS protease, the F(ab ')(2) fragments of Durva were labeled with I-124. The radioligand showed a high radiochemical purity (>96%) and outstanding stability. Western blot, quantitative real-time polymerase chain reaction, and flow cytometry were performed on the two selected NSCLC cell lines to measure the in vitro PD-L1 expression. The H460 cells showed a much higher PD-L1 expression than the A549 cells, both at the protein level and the mRNA level. In the following cell binding experiment and binding specificity assay, the labeled radioligand showed good affinity to high PD-L1 expression cells and could be blocked with excess unlabeled intact Durva. The results of the biodistribution and the positron emission tomography (PET) image showed that the peak tumor uptake of I-124-Durva-F(ab ')(2) was close to I-124-Durva, but much earlier (5.29 +/- 0.42% ID/g for I-124-Durva-F(ab ')(2) at 12 h vs 5.18 +/- 0.73% ID/g for I-124-Durva at 48 h). Compared with I-124-Durva, an accelerated blood clearance was observed for I-124-Durva-F(ab ')(2). The faster blood clearance allowed for a higher tumor-to-background ratio, which was reflected on the image in contrast. The H460 tumors showed excellent contrast as early as 4 h after injection with I-124-Durva-F(ab ')(2), and for I-124-Durva, the xenograft could not be distinguished clearly until 24 h after injection. Interestingly, I-124-Durva-F(ab ')(2) showed lower accumulations compared to other metal isotopes labeled PD-L1 antibodies in bone, liver, spleen etc., which will be beneficial for metastasis detection. Another benefit of accelerated blood clearance was a reduction in the radiation dose. According to the results of the OLINDA/EXM, the effective dose for the total body of I-124-Durva was 4.25-times greater than that of I-124-Durva-F(ab ')(2) (186 mu Sv/MBq vs 43.8 mu Sv/MBq). All of these data indicated that I-124-Durva-F(ab ')(2) is a promising immunoPET tracer for evaluating the in vivo PD-L1 levels in an NSCLC model and is expected to be successful in future clinical application.