Background/Objectives:Biology-guided radiotherapy (BgRT) is a novel technology utilizing PET radiotracer emissions to deliver image-guided adaptive RT. 18F-Fluorodeoxyglucose ([18F]FDG) is the most common PET radiotracer but has background in the liver and brain because it is taken up by viable tumor cells as well as inflammatory cells. Fibroblast activation protein (FAP) is overexpressed in cancer-associated fibroblasts with minimal expression in normal tissues. FAP inhibitors (FAPIs) bind to FAP, and a FAPI labeled with Gallium-68 (68Ga) is a novel radiotracer with high tumor selectivity. Multiple studies have compared [68Ga]Ga-FAPI-04 vs. [18F]FDG for diagnostic imaging, but [68Ga]Ga-FAPI-04 vs. [18F]FDG have never been compared in terms of their utility for BgRT.Purpose:This study was designed to assess the utility of [68Ga]Ga-FAPI-04 vs. [18F]FDG for BgRT used to treat pancreatic, liver, lung, head and neck, and cervical cancers. Methods: A radiation oncologist specializing in each cancer contoured the gross tumor volume (GTV) on [18F]FDG PET-CT and [68Ga]Ga-FAPI-04 PET-CT images. Auto-contours were generated using an auto-threshold of 40% of the maximum Standardized Uptake Value (SUV). The suitability of [68Ga]Ga-FAPI-04 vs. [18F]FDG for BgRT was evaluated by comparing Normalized Net Activity Concentration (NNA) and Normalized Target Signal (NTS) for each cancer.Results:NNA and NTS for [68Ga]Ga-FAPI-04 and [18F]FDG met the requirements for [18F]FDG-guided BgRT (NNA > 5.0 kBq/mL, NTS > 2.7) for all disease sites. NNAFAPI was significantly greater than NNAFDG for pancreatic, H&N, and cervical cancer. NTSFAPI was significantly greater than NTSFDG for pancreatic, liver, and lung cancer.Conclusions:[68Ga]Ga-FAPI-04 is a novel radiotracer for BgRT and has the greatest potential impact in the treatment of pancreatic cancer.
背景/目的：生物学引导放射治疗（BgRT）是一种利用PET放射性示踪剂发射进行图像引导自适应放射治疗的新技术。18F-氟脱氧葡萄糖（[18F]FDG）是最常用的PET放射性示踪剂，但由于其可被存活肿瘤细胞及炎症细胞摄取，在肝脏和大脑中存在本底摄取。成纤维细胞活化蛋白（FAP）在癌症相关成纤维细胞中过度表达，而在正常组织中表达极低。FAP抑制剂（FAPI）可与FAP结合，其中以镓-68（68Ga）标记的FAPI（[68Ga]Ga-FAPI-04）是一种具有高肿瘤选择性的新型放射性示踪剂。多项研究已比较[68Ga]Ga-FAPI-04与[18F]FDG在诊断成像中的应用，但两者在BgRT中的效用尚未进行过比较。 目的：本研究旨在评估[68Ga]Ga-FAPI-04与[18F]FDG在用于治疗胰腺癌、肝癌、肺癌、头颈癌及宫颈癌的BgRT中的效用。 方法：由专攻各癌种的放射肿瘤科医师分别在[18F]FDG PET-CT和[68Ga]Ga-FAPI-04 PET-CT图像上勾画大体肿瘤体积（GTV）。采用最大标准化摄取值（SUV）40%的自动阈值生成自动勾画轮廓。通过比较各癌种的归一化净活度浓度（NNA）和归一化靶信号（NTS），评估[68Ga]Ga-FAPI-04与[18F]FDG用于BgRT的适用性。 结果：对于所有病灶部位，[68Ga]Ga-FAPI-04和[18F]FDG的NNA与NTS均满足[18F]FDG引导BgRT的要求（NNA > 5.0 kBq/mL，NTS > 2.7）。在胰腺癌、头颈癌和宫颈癌中，NNAFAPI显著高于NNAFDG。在胰腺癌、肝癌和肺癌中，NTSFAPI显著高于NTSFDG。 结论：[68Ga]Ga-FAPI-04是一种可用于BgRT的新型放射性示踪剂，在胰腺癌治疗中具有最大的潜在应用价值。
肿瘤(癌症)患者之家