Abstract：
BACKGROUND: The aim of the present study was to develop a novel 64Cu-labeled cyclic peptide ([64Cu]Cu-FAP-NOX) that targets fibroblast activation protein (FAP) and may offer advantages in terms of image contrast, imaging time window, and low uptake in normal tissues.
METHODS: The novel cyclic peptide featuring with a N-oxalyl modified tail was constructed and conjugated to NOTA for 64Cu labeling. Biochemical and cellular assays were performed with A549.hFAP cells. The performance of [64Cu]Cu-FAP-NOX was compared to that of two established tracers ([64Cu]Cu-FAPI-04 and [68Ga]Ga-FAP-2286) and three different NOTA-conjugates in HEK-293T.hFAP xenograft mice using micro-PET imaging. Ex vivo biodistribution studies were performed to confirm the FAP specificity and to validate the PET data. Furthermore, a first-in-human study of this novel tracer was conducted on one patient with lung cancer.
RESULTS: Compared to [64Cu]Cu-FAPI-04, [64Cu]Cu-FAP-NOX demonstrated faster and higher rates of cellular uptake and internalization in A549.hFAP cells, but lower rates of cellular efflux. All six radiotracers were rapidly taken up by the tumor within the first 4 h post-injection. However, [64Cu]Cu-FAP-NOX had more intense tumor accumulation and slower washout from the target. The ratios of the tumor to normal tissue (including kidneys and muscles) increased significantly over time, with [64Cu]Cu-FAP-NOX reaching the highest ratio among all tracers. In the patient, [64Cu]Cu-FAP-NOX PET showed a comparable result to FDG PET in the primary malignant lesion while exhibiting higher uptake in pleural metastases, consistent with elevated FAP expression as confirmed by immunohistochemistry.
CONCLUSIONS: [64Cu]Cu-FAP-NOX is a promising FAP-targeted tracer with a highly flexible imaging time window, as evidenced by preclinical evaluation encompassing biodistribution and micro-PET studies, along with a successful patient application. Furthermore, [64Cu]Cu-FAP-NOX showed enhanced image contrast and favorable pharmacokinetic properties for FAP PET imaging, warranting translation into large cohort studies.
METHODS: The novel cyclic peptide featuring with a N-oxalyl modified tail was constructed and conjugated to NOTA for 64Cu labeling. Biochemical and cellular assays were performed with A549.hFAP cells. The performance of [64Cu]Cu-FAP-NOX was compared to that of two established tracers ([64Cu]Cu-FAPI-04 and [68Ga]Ga-FAP-2286) and three different NOTA-conjugates in HEK-293T.hFAP xenograft mice using micro-PET imaging. Ex vivo biodistribution studies were performed to confirm the FAP specificity and to validate the PET data. Furthermore, a first-in-human study of this novel tracer was conducted on one patient with lung cancer.
RESULTS: Compared to [64Cu]Cu-FAPI-04, [64Cu]Cu-FAP-NOX demonstrated faster and higher rates of cellular uptake and internalization in A549.hFAP cells, but lower rates of cellular efflux. All six radiotracers were rapidly taken up by the tumor within the first 4 h post-injection. However, [64Cu]Cu-FAP-NOX had more intense tumor accumulation and slower washout from the target. The ratios of the tumor to normal tissue (including kidneys and muscles) increased significantly over time, with [64Cu]Cu-FAP-NOX reaching the highest ratio among all tracers. In the patient, [64Cu]Cu-FAP-NOX PET showed a comparable result to FDG PET in the primary malignant lesion while exhibiting higher uptake in pleural metastases, consistent with elevated FAP expression as confirmed by immunohistochemistry.
CONCLUSIONS: [64Cu]Cu-FAP-NOX is a promising FAP-targeted tracer with a highly flexible imaging time window, as evidenced by preclinical evaluation encompassing biodistribution and micro-PET studies, along with a successful patient application. Furthermore, [64Cu]Cu-FAP-NOX showed enhanced image contrast and favorable pharmacokinetic properties for FAP PET imaging, warranting translation into large cohort studies.
摘要：
背景：本研究的目的是开发一种新型的64Cu标记的环肽（[64Cu]Cu-FAP-NOX），其靶向成纤维细胞活化蛋白（FAP），并可能在图像对比度方面提供优势，成像时间窗,和正常组织的低摄取。
方法:构建具有N-草酰经修饰的尾部的新型环状肽,并将其与NOTA缀合以进行64Cu标记。用A549进行生物化学和细胞测定。hFAP细胞。将[64Cu]Cu-FAP-NOX的性能与两种已建立的示踪剂([64Cu]Cu-FAPI-04和[68Ga]Ga-FAP-2286)和三种不同的NOTA-缀合物在HEK-293T中的性能进行比较。使用微PET成像的hFAP异种移植小鼠。进行离体生物分布研究以确认FAP特异性并验证PET数据。此外，对一名肺癌患者进行了这种新型示踪剂的首次人体研究。
结果：与[64Cu]Cu-FAPI-04相比，[64Cu]Cu-FAP-NOX在A549中表现出更快，更高的细胞摄取和内化速率。hFAP细胞，但细胞外排率较低。所有六个放射性示踪剂在注射后的前4小时内被肿瘤迅速吸收。然而,[64Cu]Cu-FAP-NOX具有更强烈的肿瘤积累和从靶标的更慢洗脱。随着时间的推移，肿瘤与正常组织（包括肾脏和肌肉）的比率显着增加，[64Cu]Cu-FAP-NOX在所有示踪剂中达到最高比例。在病人身上,[64Cu]Cu-FAP-NOXPET在原发性恶性病变中显示出与FDGPET相当的结果，而在胸膜转移中表现出更高的摄取，与免疫组织化学证实的FAP表达升高一致。
结论：[64Cu]Cu-FAP-NOX是一种有前途的FAP靶向示踪剂，具有高度灵活的成像时间窗口，包括生物分布和微型PET研究在内的临床前评估证明了这一点，以及成功的患者应用。此外，[64Cu]Cu-FAP-NOX对FAPPET成像显示出增强的图像对比度和良好的药代动力学特性，保证转化为大型队列研究。
方法:构建具有N-草酰经修饰的尾部的新型环状肽,并将其与NOTA缀合以进行64Cu标记。用A549进行生物化学和细胞测定。hFAP细胞。将[64Cu]Cu-FAP-NOX的性能与两种已建立的示踪剂([64Cu]Cu-FAPI-04和[68Ga]Ga-FAP-2286)和三种不同的NOTA-缀合物在HEK-293T中的性能进行比较。使用微PET成像的hFAP异种移植小鼠。进行离体生物分布研究以确认FAP特异性并验证PET数据。此外，对一名肺癌患者进行了这种新型示踪剂的首次人体研究。
结果：与[64Cu]Cu-FAPI-04相比，[64Cu]Cu-FAP-NOX在A549中表现出更快，更高的细胞摄取和内化速率。hFAP细胞，但细胞外排率较低。所有六个放射性示踪剂在注射后的前4小时内被肿瘤迅速吸收。然而,[64Cu]Cu-FAP-NOX具有更强烈的肿瘤积累和从靶标的更慢洗脱。随着时间的推移，肿瘤与正常组织（包括肾脏和肌肉）的比率显着增加，[64Cu]Cu-FAP-NOX在所有示踪剂中达到最高比例。在病人身上,[64Cu]Cu-FAP-NOXPET在原发性恶性病变中显示出与FDGPET相当的结果，而在胸膜转移中表现出更高的摄取，与免疫组织化学证实的FAP表达升高一致。
结论：[64Cu]Cu-FAP-NOX是一种有前途的FAP靶向示踪剂，具有高度灵活的成像时间窗口，包括生物分布和微型PET研究在内的临床前评估证明了这一点，以及成功的患者应用。此外，[64Cu]Cu-FAP-NOX对FAPPET成像显示出增强的图像对比度和良好的药代动力学特性，保证转化为大型队列研究。
