Kashihara Takanori, Kawano Yutaka, Fujimoto Shota, Segawa Tatsuya, Shimizu Mamoru, Miyake Takanori, Okamoto Koichi, Muguruma Naoki, Sato Yasushi, Takayama Tetsuji
Department of Gastroenterology and Oncology, Tokushima University Graduate School of Biomedical Sciences, 3-18-15, Kuramoto-cho, Tokushima, 770-8503, Japan.
Department of Community Medicine and Medical Science, Tokushima University Graduate School of Biomedical Sciences, Tokushima, Japan.
J Gastroenterol. 2025 May 28. doi: 10.1007/s00535-025-02264-6.
Gastrointestinal stromal tumors (GISTs) are malignant subepithelial tumors, known for their poor prognosis due to distant metastasis. Because GIST is covered by a normal mucosal layer, effective tissue biopsy under conventional endoscopy is difficult, thereby leading to delayed diagnosis and a dismal prognosis. We performed molecular imaging of GIST targeting c-KIT using fluorescence-labeled anti-c-KIT antibody/fragments and fluorescent endoscopy.
Mouse anti-human c-KIT monoclonal antibody, its F(ab') and Fab fragments were labeled with AF680. Two GIST cell lines (GIST-T1, GIST-882M) were used for experiments. Antibodies were intravenously administered to mice xenografted with GIST-T1 or GIST-882M, and each tumor was observed using IVIS Spectrum and self-developed simple fluorescent endoscopy.
The GIST-T1 cell live imaging revealed strong signals on cell membranes after 1 min incubation, and thereafter, they aggregated and internalized inside the cells within 130 min in all antibody/fragment groups. In vivo mouse experiments, AF680-labeled IgG slowly accumulated in tumors peaking at 24 h after injection. However, AF680-labeled F(ab') and Fab rapidly accumulated in tumors peaking at 1-2 h, and completely cleared from the body within 24 h. Fab showed the strongest fluorescence intensity in tumors. Fluorescence endoscopy could clearly detect GIST xenograft tumors 1-2 h after AF680-labeled F(ab') and Fab injection.
AF680-labeled antibody/fragments showed clear and specific fluorescence signals in GIST xenografts in mice. Particularly, AF680-labeled Fab showed the strongest signal intensity at 1-2 h post-administration and rapid clearance, suggestive of the safety. This approach may enable molecular imaging diagnosis of GIST by endoscopy in outpatient settings in the future.
胃肠道间质瘤（GISTs）是恶性上皮下肿瘤，因其远处转移导致预后不良而闻名。由于GIST被正常黏膜层覆盖，在传统内镜下进行有效的组织活检困难，从而导致诊断延迟和预后不佳。我们使用荧光标记的抗c-KIT抗体/片段和荧光内镜对靶向c-KIT的GIST进行了分子成像。
将小鼠抗人c-KIT单克隆抗体及其F(ab')和Fab片段用AF680标记。使用两种GIST细胞系（GIST-T1、GIST-882M）进行实验。将抗体静脉注射到接种了GIST-T1或GIST-882M的小鼠体内，并用IVIS Spectrum和自行研制的简易荧光内镜观察每个肿瘤。
GIST-T1细胞活体成像显示，孵育1分钟后细胞膜上出现强信号，此后，在所有抗体/片段组中，它们在130分钟内聚集并内化到细胞内。在体内小鼠实验中，AF680标记的IgG在肿瘤中缓慢积累，在注射后24小时达到峰值。然而，AF680标记的F(ab')和Fab在肿瘤中迅速积累，在1-2小时达到峰值，并在24小时内从体内完全清除。Fab在肿瘤中显示出最强的荧光强度。荧光内镜可以在注射AF680标记的F(ab')和Fab后1-2小时清晰地检测到GIST异种移植肿瘤。
AF680标记的抗体/片段在小鼠GIST异种移植瘤中显示出清晰且特异的荧光信号。特别是，AF680标记的Fab在给药后1-2小时显示出最强的信号强度且清除迅速，提示其安全性。这种方法未来可能使门诊环境中通过内镜对GIST进行分子成像诊断成为可能。
