Institute of Biochemistry and Clinical Biochemistry, Catholic University, Largo F. Vito 1, 00168, Rome, Italy.
Institute of Nuclear Medicine, Catholic University, Largo A. Gemelli 8, 00168, Rome, Italy.
J Pharm Biomed Anal. 2018 Jul 15;156:8-15. doi: 10.1016/j.jpba.2018.03.018. Epub 2018 Mar 12.
The aim of the present work has been the mass spectrometry characterization of the Nimotuzumab (NIM) antibody chemically modified with the bifunctional chelating agent para-S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraaza cyclododecanetetraacetic acid (p-SCN-Bn-DOTA). The conjugate, upon labeling with the pure β-emitter Y could represent a promising candidate as radiotracer for an innovative radio-guided surgery (RGS) technique, developed and patented by researchers of our group, which uses a probe system for intraoperative detection of tumor residues exploiting the selective uptake of β-emitting tracers. The results reported in this study show that multiple DOTA molecules bind to lysine residues of both light and heavy chains of the antibody and, probably, some of them are linked to the variable region of antibody. Moreover, the new mass spectrometric analysis highlights the presence of unreacted NIM in the final product. The information obtained by this work is of fundamental importance in the perspective to utilize this conjugate as a radiocompound after its labeling with Y radioisotope. Indeed, the conjugation efficiency and the presence of unreacted NIM affect the specific activity of the final radiotracer which binds specific receptor.
本工作的目的是通过质谱法对尼妥珠单抗（NIM）抗体进行化学修饰，使其与双功能螯合剂对-S-2-（4-异硫氰酸根苯甲基）-1,4,7,10-四氮杂环十二烷四乙酸（p-SCN-Bn-DOTA）偶联。该缀合物与纯β发射体 Y 标记后，可作为放射性示踪剂用于我们小组开发并获得专利的创新放射性引导手术（RGS）技术，该技术使用探针系统在术中检测肿瘤残留，利用β发射示踪剂的选择性摄取。本研究报告的结果表明，多个 DOTA 分子与抗体的轻链和重链上的赖氨酸残基结合，并且可能与抗体的可变区结合。此外，新的质谱分析突出显示了终产物中存在未反应的 NIM。这项工作获得的信息对于在使用 Y 放射性同位素标记该缀合物后将其用作放射性化合物具有重要意义。事实上，缀合效率和未反应的 NIM 的存在会影响结合特定受体的最终放射性示踪剂的比活度。
