Ma Xiaopan, Hu Biao, Zhou Xin, Wang Lei, Chen Hui, Xie Fei, Zhu Hua, Jia Bing, Yang Zhi
Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), NMPA Key Laboratory for Research and Evaluation of Radiopharmaceuticals (National Medical Products Administration), Department of Nuclear Medicine, Peking University Cancer Hospital & Institute, Beijing 100142 China; Department of Nuclear Medicine, Xiangyang Central Hospital, Affiliated Hospital of Hubei University of Arts and Science, Xiangyang 441138 China.
Department of Radiation Medicine, School of Basic Medical Sciences, Peking University, Beijing 100191 China.
Bioorg Chem. 2025 Mar;156:108222. doi: 10.1016/j.bioorg.2025.108222. Epub 2025 Jan 28.
Immunohistochemistry (IHC) for PD-L1 detection is limited by its invasiveness and heterogeneity of tumors. To address these challenges, a new PD-L1-targeted nanobody-based immune-PET radiotracer [F]AlF-APN09 was developed using the site-specific radiolabeling method with the complexing agent (Mal-RESCA) under mild conditions. [F]AlF-APN09 was prepared at room temperature (pH 4.6-4.8) within 20 min with satisfactory radiochemical yields (45.8 ± 4.48 %, non-decay corrected), high radiochemical purity (>98 %) and moderate apparent molar activity (15-35 GBq/μmol), and remained stable in both PBS and 5 % HSA after 4 h (>90 %). Cell uptake studies indicated variable levels of surface PD-L1 expression in the following order: A549 > H1975 > A549. In micro-PET/CT imaging, A549 and H1975 tumors were distinctly visualized in a 6.0:1 and 3.2:1 ratios over PD-L1-negative A549 tumors in vivo. Ex vivo biodistribution studies showed tumor uptake values of 6.47 ± 1.06 %ID/g (A549) and 2.27 ± 0.19 %ID/g (H1975), significantly higher than 0.90 ± 0.28 %ID/g in A549 tumors. The estimated effective radiation dose in humans was 8.65E-03 mSv/MBq, lower than that of conventional [F]FDG. First-in-human imaging was conducted on a single resectable non-small cell lung cancer (NSCLC) subject without any adverse reactions. The radiotracer exhibited renal excretion with minimal hepatobiliary clearance. Tumor uptake reached SUV 4.20 at 2 h post-injection, demonstrating high contrast and rapid clearance. After PD-1 inhibitor immunotherapy and chemotherapy, the subject showed a therapeutic response and postoperative pathological specimens confirmed a major pathological response (MPR). These results suggest that we have successfully developed a new PD-L1-targeted nanobody PET tracer using the site-specific labeling method with the complexing agent (Mal-RESCA) within 20 min under mild conditions and [F]AlF-APN09 is a promising noninvasive PET radiotracer for visualizing PD-L1 expression in tumors, offering rapid tumor targeting, excellent signal-to-noise ratios, and favorable clearance properties.
用于检测程序性死亡受体配体1（PD-L1）的免疫组织化学（IHC）受到肿瘤侵袭性和异质性的限制。为应对这些挑战，采用温和条件下与络合剂（Mal-RESCA）的位点特异性放射性标记方法，开发了一种基于新型PD-L1靶向纳米抗体的免疫正电子发射断层显像（PET）放射性示踪剂[F]AlF-APN09。[F]AlF-APN09在室温（pH 4.6 - 4.8）下20分钟内制备完成，具有令人满意的放射化学产率（45.8 ± 4.48%，未进行衰变校正）、高放射化学纯度（>98%）和适度的表观摩尔活度（15 - 35 GBq/μmol），并且在4小时后在磷酸盐缓冲盐水（PBS）和5%人血清白蛋白（HSA）中均保持稳定（>90%）。细胞摄取研究表明，表面PD-L1表达水平存在差异，顺序如下：A549 > H1975 > A549。在微型PET/CT成像中，体内A549和H1975肿瘤与PD-L1阴性的A549肿瘤的显像比例分别为6.0:1和3.2:1。体外生物分布研究显示，肿瘤摄取值分别为6.47 ± 1.06%ID/g（A549）和2.27 ± 0.19%ID/g（H1975），显著高于A549肿瘤中的0.90 ± 0.28%ID/g。估计人体有效辐射剂量为8.65E-03 mSv/MBq，低于传统的[F]氟代脱氧葡萄糖（[F]FDG）。对一名可切除的非小细胞肺癌（NSCLC）患者进行了首例人体成像，未出现任何不良反应。该放射性示踪剂经肾脏排泄，肝胆清除极少。注射后2小时肿瘤摄取达到标准化摄取值（SUV）4.20，显示出高对比度和快速清除。在接受程序性死亡受体1（PD-1）抑制剂免疫治疗和化疗后，该患者显示出治疗反应，术后病理标本证实为主要病理反应（MPR）。这些结果表明，我们已成功使用温和条件下与络合剂（Mal-RESCA）的位点特异性标记方法在20分钟内开发出一种新型PD-L1靶向纳米抗体PET示踪剂，并且[F]AlF-APN09是一种有前景的无创PET放射性示踪剂，可用于可视化肿瘤中PD-L1的表达，具有快速肿瘤靶向、出色的信噪比和良好的清除特性。
