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碳酸酐酶IX(CA IX)在多种实体肿瘤中过表达,而在相应的正常组织中没有表达或表达水平很低,是肿瘤诊断和治疗中的一个潜在靶点。利用99Tcm直接标记抗CA IX单克隆抗体(MAb),在最佳的标记条件下可以得到标记率为85%的目标产物99Tcm-MAb。此标记物在新生牛血清和PBS中稳定性良好。99Tcm-MAb通过尾静脉注入到荷HT-29肿瘤鼠进行显像,注射24 h后在肿瘤处没有看到明显的放射性浓集。注射24 h后的体内分布实验显示99Tcm-MAb在肿瘤内的摄取率较低。将125I-MAb注入到荷HT-29肿瘤鼠进行显像,注射48 h后在肿瘤处可以看到明显的放射性浓集。由于抗体在体内循环代谢速度较慢,而99Tcm的半衰期相对较短,故99Tcm标记抗CA IX单抗不适用于靶向CA IX的肿瘤显像。
Carbonic anhydrase IX (CA IX) is overexpressed in many solid tumors but not expressed in the corresponding normal tissues or has a low expression level, which is a potential target for tumor diagnosis and treatment. Using 99Tcm direct anti-CA IX monoclonal antibody (MAb), the target product 99Tcm-MAb with the labeling efficiency of 85% can be obtained under the optimal labeling conditions. This marker has good stability in neonatal bovine serum and PBS. 99Tcm-MAb was injected into the HT-29 tumor-bearing mice through the tail vein for imaging. After 24 h of injection, no obvious radioactive concentration was observed in the tumor. In vivo distribution experiments 24 h after injection showed a lower uptake of 99Tcm-MAb in the tumor. 125I-MAb was injected into HT-29 tumor-bearing mice for visualization. After 48 h of injection, significant radioactive concentration was observed in the tumor. The 99Tcm-labeled anti-CA IX mAb is not suitable for tumor imaging targeting CA IX due to the slower rate of circulating antibodies in the body and the relatively short half-life of 99Tcm.