Noninvasive imaging technologies are increasingly used in preclinical drug research for the pharmacokinetic analysis of therapeutic compounds in living animals over time. The different preclinical imaging modalities available differ intrinsically in their detection principle and thus might exhibit limitations for a specific application. Here, we systematically investigated the performance of advanced fluorescence-mediated tomography (FMT)/CT in comparison to PET/MRI for quantitative analysis of the biodistribution of different antibody formats and dependence on the required imaging label in squamous cell carcinoma xenografts. Methods: Different formats of an antibody (monoclonal antibody and the antigen binding fragments F(ab′)₂ and Fab) targeting epidermal growth factor receptor were labeled with Alexa750 or ⁶⁴Cu-NODAGA and injected intravenously into separate cohorts of nude mice bearing subcutaneous A-431 tumors. Two and 24 h after injection, the mice were measured by FMT/CT and PET/MRI. Probe accumulation was quantitatively assessed in organs and tumors. In vivo data were compared between modalities and correlated with ex vivo fluorescence, γ-counting, and electrochemiluminescence immunoassay. Results: Both imaging methods faithfully monitored the biodistribution and elimination routes of the compounds, and organ accumulation measured by FMT/CT and PET/MRI correlated significantly with ex vivo measurements. In addition, the accumulation in kidney, muscle, and tumor tissue correlated between FMT/CT and PET/MRI. However, the pharmacokinetics of the Alexa750-labeled antibody formats showed shorter blood half-times and higher liver uptake than the radiolabeled counterparts. Conclusion: FMT/CT imaging allows quantifying the biodistribution of antibodies in nude mice and provides an alternative to PET analysis in preclinical drug research. However, even for large molecules, such as monoclonal antibodies, Alexa750 labeling can change pharmacokinetics and trigger liver uptake.

随着时间的推移，无创成像技术越来越多地用于临床前药物研究中，用于对动物体内治疗性化合物进行药代动力学分析。可用的不同的临床前成像模式本质上在其检测原理方面有所不同，因此可能在特定应用中显示出局限性。在这里，我们系统地研究了先进的荧光介导层析成像（FMT）/ CT与PET / MRI的性能，以定量分析不同抗体形式的生物分布以及对鳞状细胞癌异种移植物的所需成像标记的依赖性。方法：不同形式的抗体（单克隆抗体和抗原结合片段F（ab'）₂靶向表皮生长因子受体的Fab和Fab）用Alexa750或⁶⁴ Cu-NODAGA标记，并静脉注射到带有皮下A-431肿瘤的裸鼠的单独队列中。注射后2小时和24小时，通过FMT / CT和PET / MRI测量小鼠。在器官和肿瘤中定量评估探针的积累。在模态之间比较体内数据，并将其与离体荧光，γ计数和电化学发光免疫分析法相关联。结果：两种成像方法均能忠实地监测化合物的生物分布和消除途径，并且通过FMT / CT和PET / MRI测量的器官蓄积与离体测量值显着相关。此外，FMT / CT和PET / MRI之间在肾脏，肌肉和肿瘤组织中的蓄积相关。但是，Alexa750标记的抗体形式的药代动力学显示，血液半衰期短且肝脏吸收率高于放射性标记的对应物。结论： FMT / CT成像可以量化裸鼠中抗体的生物分布，并为临床前药物研究中的PET分析提供了另一种选择。但是，即使对于大分子，例如单克隆抗体，Alexa750标记也可以改变药代动力学并触发肝脏吸收。