Near‐infrared fluorescence‐labeled anti‐PD‐L1‐mAb for tumor imaging in human colorectal cancer xenografted mice

• Published in: Journal of cellular biochemistry Vol. 120; no. 6; pp. 10239 - 10247
• Main Authors: Zhang, Mingyu, Jiang, Huijie, Zhang, Rongjun, Jiang, Hao, Xu, Hailong, Pan, Wenbin, Gao, Xiaolin, Sun, Zhongqi
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2019; John Wiley and Sons Inc
• Subjects: Animals; Antibodies, Monoclonal - immunology; Antibodies, Monoclonal - metabolism; Apoptosis; B7-H1 Antigen - immunology; B7-H1 Antigen - metabolism; Biomarkers; Biotechnology; Cancer; Cell Line, Tumor; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - immunology; Colorectal Neoplasms - metabolism; Colorectal Neoplasms - pathology; Feasibility Studies; Female; Flow cytometry; Fluorescence; Heterografts - immunology; Heterografts - metabolism; Humans; Immunoconjugates - immunology; Immunoconjugates - metabolism; Immunotherapy; L1 protein; Liver; Medical imaging; Mice; Mice, Inbred BALB C; Mice, Nude; Monoclonal antibodies; Mouse devices; noninvasive imaging; optical imaging; Optical Imaging - methods; PD-L1 protein; programmed death ligand‐1/programmed death ligand‐1 checkpoint; Proteins; Reproducibility of Results; Spleen; Tumors; Xenografts; noninvasive imaging; colorectal cancer; programmed death ligand-1/programmed death ligand-1 checkpoint; optical imaging; immunotherapy
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/jcb.28308

The expression of programmed death ligand‐1 (PD‐L1) in tumor has been used as a biomarker to predict the anti‐PD‐L1 immunotherapy response. To develop a noninvasive imaging technique to monitor the dynamic changes in PD‐L1 expression in colorectal cancer (CRC), we labeled an anti‐PD‐L1 monoclonal antibody with near‐infrared (NIR) dye and tested the ability of the NIR‐PD‐L1‐mAb probe to monitor the PD‐L1 expression in CRC‐xenografted mice by performing optical imaging. Consistent with the expression levels of PD‐L1 protein in three CRC cell lines in vitro by flow cytometry and Western blot analyses, our in vivo imaging showed the highest fluorescence signal of the xenografted tumors in mice bearing SW620 CRC cells, followed by tumors derived from SW480 and HCT8 cell lines. We detected the highest fluorescent intensity of the tumor at 120 hours after injection of NIR‐PD‐L1‐mAb. The highest fluorescence intensity was seen in the tumor, followed by the spleen and the liver in SW620 xenografted mice. In SW480 and HCT8 xenografted mice, however, the highest fluorescent signals were detected in the spleen, followed by the liver and the tumor. Our findings indicate that SW620 cells express a higher level of PD‐L1, and the NIR‐PD‐L1‐mAb binding to PD‐L1 on the surface of CRC cells was specific. The technique was safe and could provide valuable information on PD‐L1 expression of the tumor for development of a therapeutic strategy of personized targeted immunotherapies as well as treatment response of patients with CRC. To develop a new noninvasive imaging technique to monitor the dynamic changes in programmed death ligand‐1 (PD‐L1) expression in colorectal cancer (CRC), anti‐PD‐L1 monoclonal antibody was labeled with near‐infrared (NIR) dye for evaluation of PD‐L1 expression in CRC‐xenografted mice by optical imaging. Our in vivo imaging observed the highest fluorescence signal of the xenografted tumors in mice bearing SW620 CRC cells, followed by tumors derived from SW480 and HCT8 cell lines, with the highest fluorescent intensity of tumor to background at 120 hours after injection of NIR‐PD‐L1‐mAb. Our findings indicate that the NIR‐PD‐L1‐mAb binding to CRC cells was specific, safe and reliable, and the technique could provide valuable information on PD‐L1 expression of the tumor for the development of a therapeutic strategy of personized targeted immunotherapies as well as treatment response of patients with CRC.