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肿瘤的发生和发展与其微环境密切相关。肿瘤微环境是一个包含肿瘤细胞、成纤维细胞、免疫细胞、血管内皮细胞和细胞外基质等复杂成分的特定环境,其中,肿瘤相关成纤维细胞(cancer-associated fibroblasts,CAFs)是肿瘤微环境中最关键的成分之一[1],具有分泌多种细胞因子及抑制正常免疫应答的功能。成纤维细胞激活蛋白(fibroblast activationprotein,FAP)是CAFs表面的抗原分子,最初被称为F19抗原,是一种跨膜糖蛋白,属于丝氨酸蛋白酶类,由分子量为95 kDa的α亚单位和105 kDa的β亚单位组成二聚体[2]。FAP具有分解明胶和Ⅰ型胶原的胶原酶活性以及类似二肽基肽酶的活性,能够降解和重建细胞外基质并促进肿瘤新生血管的形成,可参与基质重构、血管生成、化疗耐药以及免疫抑制等多种促进肿瘤活性的途径。同时,由于FAP在正常组织中几乎不表达,故其成为恶性肿瘤诊疗的新型靶点[3-5]。
PET是一种通过放射性核素标记的探针在体内示踪分子和细胞动态变化的分子影像学技术,与CT联用可实现对疾病的精准诊断。FAP抑制剂(FAP inhibitor,FAPI)是基于喹啉结构合成的靶向FAP的小分子化合物,经放射性核素标记后可作为恶性肿瘤的PET/CT新型显像剂[6-7],主要包括125I-FAPI-01、177Lu-FAPI-02、90Y-FAPI-04、68Ga-FAPI-02、68Ga-FAPI-04和68Ga-FAPI-46等。其中,关于68Ga-FAPI显像剂的研究最多,因其具有制备简便、患者无需进行静息和禁食准备及T/NT高等优势[8],现已应用于多种恶性肿瘤的诊断,尤其在神经胶质瘤、食管癌、肝细胞癌和胰腺导管腺癌(pancreatic ductal adenocarcinoma,PDAC)中已被证实具有良好的应用前景[9](表1)。我们重点综述了68Ga-FAPI PET/CT在上述恶性肿瘤中的临床价值。
不同肿瘤类型的显像剂 研究者 样本量 主要发现 神经胶质瘤 68Ga-FAPI-02/04 Röhrich等[10] 18 高级别胶质瘤高摄取(SUVmax=2.8±0.6),低级别胶质瘤轻度摄取(SUVmax=0.35±0.10),具有无创性鉴别低级别与高级别胶质瘤的潜力。 68Ga-FAPI-04 Chen等[11] 4 T/NT高(最高可达16.9)。 68Ga-FAPI-04 Windisch等[12] 13 与MRI相比,在68Ga FAPI PET/CT图像中勾画的肿瘤靶区更为精准,且能够最大程度地减少勾画到周围正常组织的概率(P=0.022)。 食管癌 68Ga-FAPI-04/46 Ristau等[13] 7 T/NT高(最高可达11),转移性淋巴结在视觉分析中更易被发现。 68Ga-FAPI-04 Chen等[11] 4 对转移性淋巴结的诊断灵敏度和准确率均高于18F-FDG PET/CT(86.4% vs. 45.5%;74.4% vs. 59.0%)。 肝细胞癌 68Ga-FAPI-04 Shi等[14] 17 诊断灵敏度高,特别是FAP表达水平高的低分化型肝细胞癌。 68Ga-FAPI-04 Shi等[15] 14 诊断灵敏度明显高于18F-FDG PET/CT(100% vs.55%)。 68Ga-FAPI-04 Guo等[16] 16 诊断灵敏度高于18F-FDG PET/CT(94% vs.69%)。 68Ga-FAPI-04 Geist等[17] 8 基于68Ga-FAPI-04 PET/CT构建的动力学模型具有无创性鉴别肝细胞癌和非肝细胞癌的潜力。 PDAC 68Ga-FAPI-04/46 Röhrich等[18] 19 可重新评估病灶的受累情况,调整PDAC的肿瘤分期。 非小细胞肺癌 68Ga-FAPI-74 Giesel等[19] 10 有助于勾画放疗靶区。 头颈部恶性肿瘤 68Ga-FAPI Syed等[20] 14 有助于勾画放疗靶区。 鼻咽癌 68Ga-FAPI-04 Chen等[11] 6 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 卵巢癌 68Ga-FAPI-04 Chen等[11] 4 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 软组织肉瘤 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 神经内分泌肿瘤 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 宫颈癌 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 胃癌 68Ga-FAPI Pang等[21] 20 更加灵敏地检测出原发灶和转移灶。 十二指肠癌 68Ga-FAPI Pang等[21] 2 更加灵敏地检测出原发灶和转移灶。 结直肠癌 68Ga-FAPI Pang等[21] 8 更加灵敏地检测出原发灶和转移灶。 注:FAPI 为成纤维细胞激活蛋白抑制剂;PET 为正电子发射断层显像术;CT 为计算机体层摄影术;PDAC 为胰腺导管腺癌;SUVmax为最大标准化摄取值;T/NT为靶/非靶比值;MRI 为磁共振成像;FDG 为氟脱氧葡萄糖;FAP 为成纤维细胞激活蛋白 表 1 68Ga-FAPI PET/CT在恶性肿瘤中的临床应用
Table 1. Summary table of the clinical application of 68Ga-FAPI PET/CT in malignant tumors
68Ga-FAPI PET/CT在恶性肿瘤中的临床应用
Clinical application of 68Ga-FAPI PET/CT in malignant tumors
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摘要: 成纤维细胞激活蛋白(FAP)作为肿瘤相关成纤维细胞(CAFs)的分子标志物之一,在激活的CAFs中高度特异性表达。FAP具有促进肿瘤侵袭、转移和免疫逃逸的作用,可作为恶性肿瘤诊疗的重要靶点。镓-68标记的FAP抑制剂(68Ga-FAPI)是基于FAP合成的小分子探针,经PET/CT显像可实现FAP在体内的可视化。目前,68Ga-FAPI PET/CT已成功应用于神经胶质瘤、食管癌、肝细胞癌和胰腺导管腺癌等恶性肿瘤的诊断和分期。笔者综述了68Ga-FAPI PET/CT在恶性肿瘤中的临床应用情况。
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关键词:
- 正电子发射断层显像术 /
- 体层摄影术,X线计算机 /
- 放射性核素显像 /
- 成纤维细胞激活蛋白抑制剂
Abstract: Fibroblast activation protein (FAP), as one of the molecular markers of cancer-associated fibroblasts (CAFs), is highly specifically expressed in activated CAFs. FAP can be used as a theranostic target for malignant tumors since it can promote tumor invasion, metastasis and immune escape. Gallium-68-labeled FAP inhibitor (68Ga-FAPI) is a small molecular probe synthesized based on FAP, which can be visualized in vivo by PET/CT imaging. At present, 68Ga-FAPI PET/CT has been successfully used in the diagnosis and staging of glioma, esophageal cancer, hepatocellular carcinoma, pancreatic ductal adenocarcinoma and other malignant tumors. This paper reviews the clinical application of 68Ga-FAPI PET/CT in malignant tumors. -
表 1 68Ga-FAPI PET/CT在恶性肿瘤中的临床应用
Table 1. Summary table of the clinical application of 68Ga-FAPI PET/CT in malignant tumors
不同肿瘤类型的显像剂 研究者 样本量 主要发现 神经胶质瘤 68Ga-FAPI-02/04 Röhrich等[10] 18 高级别胶质瘤高摄取(SUVmax=2.8±0.6),低级别胶质瘤轻度摄取(SUVmax=0.35±0.10),具有无创性鉴别低级别与高级别胶质瘤的潜力。 68Ga-FAPI-04 Chen等[11] 4 T/NT高(最高可达16.9)。 68Ga-FAPI-04 Windisch等[12] 13 与MRI相比,在68Ga FAPI PET/CT图像中勾画的肿瘤靶区更为精准,且能够最大程度地减少勾画到周围正常组织的概率(P=0.022)。 食管癌 68Ga-FAPI-04/46 Ristau等[13] 7 T/NT高(最高可达11),转移性淋巴结在视觉分析中更易被发现。 68Ga-FAPI-04 Chen等[11] 4 对转移性淋巴结的诊断灵敏度和准确率均高于18F-FDG PET/CT(86.4% vs. 45.5%;74.4% vs. 59.0%)。 肝细胞癌 68Ga-FAPI-04 Shi等[14] 17 诊断灵敏度高,特别是FAP表达水平高的低分化型肝细胞癌。 68Ga-FAPI-04 Shi等[15] 14 诊断灵敏度明显高于18F-FDG PET/CT(100% vs.55%)。 68Ga-FAPI-04 Guo等[16] 16 诊断灵敏度高于18F-FDG PET/CT(94% vs.69%)。 68Ga-FAPI-04 Geist等[17] 8 基于68Ga-FAPI-04 PET/CT构建的动力学模型具有无创性鉴别肝细胞癌和非肝细胞癌的潜力。 PDAC 68Ga-FAPI-04/46 Röhrich等[18] 19 可重新评估病灶的受累情况,调整PDAC的肿瘤分期。 非小细胞肺癌 68Ga-FAPI-74 Giesel等[19] 10 有助于勾画放疗靶区。 头颈部恶性肿瘤 68Ga-FAPI Syed等[20] 14 有助于勾画放疗靶区。 鼻咽癌 68Ga-FAPI-04 Chen等[11] 6 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 卵巢癌 68Ga-FAPI-04 Chen等[11] 4 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 软组织肉瘤 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 神经内分泌肿瘤 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 宫颈癌 68Ga-FAPI-04 Chen等[11] 3 评估转移性淋巴结的受累情况,进行更为准确的肿瘤分期。 胃癌 68Ga-FAPI Pang等[21] 20 更加灵敏地检测出原发灶和转移灶。 十二指肠癌 68Ga-FAPI Pang等[21] 2 更加灵敏地检测出原发灶和转移灶。 结直肠癌 68Ga-FAPI Pang等[21] 8 更加灵敏地检测出原发灶和转移灶。 注:FAPI 为成纤维细胞激活蛋白抑制剂;PET 为正电子发射断层显像术;CT 为计算机体层摄影术;PDAC 为胰腺导管腺癌;SUVmax为最大标准化摄取值;T/NT为靶/非靶比值;MRI 为磁共振成像;FDG 为氟脱氧葡萄糖;FAP 为成纤维细胞激活蛋白 -
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