生物素化后的^(111)In-MN14使用体外生物吸附柱对其药代动力学的影响

Biotinylation pharmacoki netics extracorporeal adsorption of humanized Mab ^(111)In-MN14 using an avidin-affinity column in rats

目的①在大鼠体内观察生物素化对人源化单抗MN14的生物学分布及药代动力学的影响;②通过静脉注射^(111)In-MN14-生物素观察体外生物吸附柱能否降低全身、血以及放射敏感脏器的放射性活度。方法人源化单抗MN14可特异性地识别癌胚抗原(CEA)。实验中用大鼠93只。首先用NHS-生物素或硫代-NHS-生物素对单抗MN14进行生物素化使得它可被由亲合素颗粒组成的吸附柱吸附;13只大鼠实施体外吸附柱(治疗组):整个过程大约有3倍的血容量通过吸附柱,耗时约2.5 h。对全身、血以及放射敏感脏器的放射性活度进行监测。结果高压液相色谱仪显示,在使用NHS-生物素时,生物素/单抗比率很低时就有碎片形成;而使用硫代-NHS-生物素时,即无碎片也无凝聚体产生。注射6 h后实施体外吸附,全身及血中的放射性活度分别下降64%和98%;放射敏感脏器中放射性活度也有不同程度的降低,从肝脏的39%到肺及骨髓的84%。结论本研究显示硫代-NHS-生物素可安全地使^(111)InMN14生物素化,既不影响其免疫原性也不影响其在体内的分布。使用体外生物吸附柱可有效地降低全身、血以及放射敏感脏器的放射性活度。

Objective To investigate the influence of biotinylation on pharmacokinetics and biodistri-bution of humanized Mab^（111）In-MN14 and to validate the effect of subsequent ECAT on avtivity reduction in the whole body,in blood and in various organs after i.v. administration of biotinylated^（111）In-hMN14 in rats. Methods Humanized Mab MN14 recognizes the carcinoembryonic antigen. Ninety-three rats were used.^（111）In-hMN14-DOTA was biotinylated using NHSbiotin or Sulfo-NHS-biotin enabling antibodies to be absorbed on the avidin-agarose volumn. Eight rats underwent ECAT,which implied that three blood volumes were passed through the column during 2.5 h. Whole body counts and blood activity were monitored. At dissections,organs of interest were removed and measuerd for activity-content. Results HPLC showed signs of fragmentation at a low ratio of NHS-biotin/mg of Mab. No fragmentation or aggregation was observed using sulfo-NHS-biotin. When ECAT started at 6h.p.i, whole body and blood activity were reduced by 64% and 98%,respectively. The uptake in organs sensitive to radiation was also reduced,varying between 39% for the liver and 84% for the lungs and bone marrow. Conclusion^（111）In-hMN14 can be safely biotinylated using sulfo-NHS-biotin without significantly affecting antigenicity and biodistribution of the antibody. ECAT based on the avidin-biotin concept effectively removed biotinylated^（111）In-hMN14 from blood circulation and reduced activity in radiosensitive organs.