中文摘要：

目的研究EGFR靶向药物西妥昔单克隆抗体（Cetuximab，C225）的99^Tc^m标记方法，并应用99^Tc^m亚氨基噻吩-西妥昔（99^Tc^m-IT-Cetuximab）分子探针进行叮显像。方法应用二亚氨基噻吩（2．IT）双功能螯合剂制备99^Tc^m-IT-Cetuximab，研究标记后抗体的稳定性、分子完整性以及体内分布情况。建立荷人肺癌A549肿瘤裸鼠模型，评价^Tc^m-IT-Cetuximab分子探针进行模型动物γ显像的效果。结果99^Tc^m-IT-Cetuximab标记率为93．15％，纯化后的放化纯为96．46％。99^Tc^m-IT-Cetuximab在质量分数5％HSA中稳定性良好，4℃放置24h放化纯大于80％。体内生物分布表明99^Tc^m-IT-Cetuximab在肝肾摄取高，符合抗体在体内正常的代谢途径，肿瘤靶向性良好，注射后4h肿瘤摄取最高达到（3．417±0．769）％ID／g。随着时间的延长，T／NT比值进一步提高，注射后24h肿瘤／血液比值为1．454±0．174。γ显像也证实，随着显像时间的延长，该分子探针有明显的肿瘤靶向性。结论成功制备99^Tc^m-IT-Cetuximab分子探针，其具有较好的放化性质及体内外稳定性，能对荷人肺癌细胞（A549）裸鼠模型进行靶向显像。

英文摘要：

Objective To prepare and evaluate 99^Tc^m radiolabeled Cetuximab （C225） for imaging of EGFR specific binding. Methods Cetuximab antibody was reduced by 2-iminothiophene （2-IT）. The radiolabeling of IT-Cetuximab with 99^Tc^m（99^Tc^m-IT-Cetuximab） was analyzed by HPLC, and was tested for in vitro stability and molecular integrity. The human lung cancer line （ A549 ） -beating nude mouse model was prepared for biodistribution and tumor targeted study. Tumor uptake was also measured by in vivo γ ima- ging. Results The labeling efficiency was 93.15%. The radiochemical purity was 96.46% after purification. The in vitro stability was good in 5% liSA,in which the radiochemical purity maintained above 80% at 4 ℃ for 24 h. 99Tcm-IT-Cetuximab showed good specific binding to tumor with peak uptake of （3.417±0.769） %ID/g af- ter 4 h. The T/NT ratio of blood increased to 1.454-＋0.174 at 24 h. γ imaging of A549-bearing nude mice xenografts also showed high T/NT ratio. Conclusions 99^Tc^m-IT-Cetuximab molecular probe could be pre- pared with high radiolabeling yield and radiochemical purity. It has excellent in vitro and in vivo stability, and shows specific uptake in A549 tumor.