Preliminary clinical study of a novel FAP-targeted PET tracer 64Cu-FAPI-XT117 in malignant solid tumors: a comparative study with 18F-FDG

Xi HE; Meijuan ZHOU; Peng HOU; Kaixiang ZHONG; Youcai LI; Jie LYU; Miao KE; Ruiyue ZHAO; Shaoyu LIU; Yimin FU; Huizhen ZHONG; Xinlu WANG

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Preliminary clinical study of a novel FAP-targeted PET tracer 64Cu-FAPI-XT117 in malignant solid tumors: a comparative study with 18F-FDG

VernacularTitle:新型FAP靶向示踪剂 64Cu-FAPI-XT117在恶性实体肿瘤中的初步临床研究：与 18F-FDG的对比研究
Author: Xi HE ¹ ; Meijuan ZHOU ¹ ; Peng HOU ¹ ; Kaixiang ZHONG ¹ ; Youcai LI ¹ ; Jie LYU ¹ ; Miao KE ¹ ; Ruiyue ZHAO ¹ ; Shaoyu LIU ¹ ; Yimin FU ¹ ; Huizhen ZHONG ¹ ; Xinlu WANG ¹
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1. 广州医科大学附属第一医院核医学科，广州　510120
Publication Type:Journal Article
Keywords: Neoplasms; Membrane proteins; Copper radioisotopes; Positron-emission tomography; Tomography, X-ray computed; Fluorodeoxyglucose F18; FAP
From: Chinese Journal of Nuclear Medicine and Molecular Imaging 2025;45(12):708-713
CountryChina
Language:Chinese
Abstract: Objective:To systematically evaluate the safety and efficacy of the novel fibroblast activation protein (FAP)-targeted tracer 64Cu-FAP inhibitor (FAPI)-XT117 in patients with malignant solid tumors, and to compare with 18F-FDG. Methods:This self-controlled study was conducted on fifteen patients (8 males, 7 females; age (60 ±9) years) with malignant solid tumors from the First Affiliated Hospital of Guangzhou Medical University between July 2023 and December 2023. Each subject underwent 64Cu-FAPI-XT117 PET/CT at 30, 60, and 120min post-injection and was assigned to three dose cohorts (111MBq, 148MBq, and 185MBq; 5 patients in each cohort), and safety assessments were conducted within 24h after injection. In addition, all patients underwent 18F-FDG PET/CT at 60min post-injection. Time-activity curves were generated for 64Cu-FAPI-XT117, and the dosimetry was calculated. Image quality was evaluated using a 5-point Likert scale, and the optimal injected activity and imaging time point were determined. The paired t test was used to compare differences of the lesion detection count and SUV max between 64Cu-FAPI-XT117 and 18F-FDG PET/CT. Results:64Cu-FAPI-XT117 was well tolerated, with no adverse events reported. Time-activity curves of 68Ga-FAPI-XT117 revealed prominent uptake in the uterus, while the background activity in other organs remained low, with the whole-body effective dose of (0.0084±0.0021)mSv/MBq. The optimal imaging time point for 64Cu-FAPI-XT117 PET/CT was 60min post-injection, with an optimal administered activity of 111MBq. Compared with 18F-FDG, 64Cu-FAPI-XT117 demonstrated significantly higher uptake and more lesions in lymph-node metastases (SUV max: 8.6±3.8 vs 15.3±6.8, t=2.33, P=0.048; number of lesions: 8.3±5.4 vs 15.0±6.4; t=4.21, P=0.003) and distant metastases (SUV max: 11.8±3.7 vs 20.9±7.2, t=3.66, P=0.022; number of lesions: 7.0±3.2 vs 12.4±3.7, t=2.86, P=0.046). Conclusions:64Cu-FAPI-XT117 PET/CT is well tolerated in patients with solid tumors, with a controllable radiation risk. Moreover, it outperforms 18F-FDG PET/CT in the assessment of metastases.