Multiscale imaging of therapeutic anti-PD-L1 antibody localization using molecularly defined imaging agents

Journal of Nanobiotechnology

Ferenc A. Scheeren¹  Sandra Heskamp²  Martin Gotthardt²  Janneke D. M. Molkenboer-Kuenen²  Peter J. Wierstra²  Carl G. Figdor³  Johan M. S. van der Schoot³  Duco van Dalen³  Iris M. Hagemans³  Martijn Verdoes³  Kas Steuten³  Martin ter Beest³  Olga Ilina³ 

[1] Department of Dermatology, Leiden University Medical Centre;Department of Medical Imaging, Nuclear Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center;Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center;

关键词: Fluorescence imaging;    Nuclear imaging;    Immune checkpoints;    Antibody;    Cancer;   

DOI  :  10.1186/s12951-022-01272-5

来源: DOAJ

【 摘 要 】

Abstract Background While immune checkpoint inhibitors such as anti-PD-L1 antibodies have revolutionized cancer treatment, only subgroups of patients show durable responses. Insight in the relation between clinical response, PD-L1 expression and intratumoral localization of PD-L1 therapeutics could improve patient stratification. Therefore, we present the modular synthesis of multimodal antibody-based imaging tools for multiscale imaging of PD-L1 to study intratumoral distribution of PD-L1 therapeutics. Results To introduce imaging modalities, a peptide containing a near-infrared dye (sulfo-Cy5), a chelator (DTPA), an azide, and a sortase-recognition motif was synthesized. This peptide and a non-fluorescent intermediate were used for site-specific functionalization of c-terminally sortaggable mouse IgG1 (mIgG1) and Fab anti-PD-L1. To increase the half-life of the Fab fragment, a 20 kDa PEG chain was attached via strain-promoted azide-alkyne cycloaddition (SPAAC). Biodistribution and imaging studies were performed with 111In-labeled constructs in 4T1 tumor-bearing mice. Comparing our site-specific antibody-conjugates with randomly conjugated antibodies, we found that antibody clone, isotype and method of DTPA conjugation did not change tumor uptake. Furthermore, addition of sulfo-Cy5 did not affect the biodistribution. PEGylated Fab fragment displayed a significantly longer half-life compared to unPEGylated Fab and demonstrated the highest overall tumor uptake of all constructs. PD-L1 in tumors was clearly visualized by SPECT/CT, as well as whole body fluorescence imaging. Immunohistochemistry staining of tumor sections demonstrated that PD-L1 co-localized with the fluorescent and autoradiographic signal. Intratumoral localization of the imaging agent could be determined with cellular resolution using fluorescent microscopy. Conclusions A set of molecularly defined multimodal antibody-based PD-L1 imaging agents were synthesized and validated for multiscale monitoring of PD-L1 expression and localization. Our modular approach for site-specific functionalization could easily be adapted to other targets. Graphical Abstract

【 授权许可】

Unknown