Construction of a 124I-Labeled Specific Antibody for the Noninvasive Detection of Mesothelin-Overexpressing Tumors

Xingguo Hou; Feng Wang; Xiangxi Meng; Dan Li; Jin Ding; Yan Chen; Zilei Wang; Hua Zhu; Zhi Yang

doi:10.1021/acs.molpharmaceut.2c00342

Construction of a ¹²⁴I-Labeled Specific Antibody for the Noninvasive Detection of Mesothelin-Overexpressing Tumors

Mol Pharm. 2022 Oct 3;19(10):3623-3631. doi: 10.1021/acs.molpharmaceut.2c00342. Epub 2022 Jul 29.

Authors

Xingguo Hou^{1

2}, Feng Wang¹, Xiangxi Meng¹, Dan Li¹, Jin Ding¹, Yan Chen^{1

3}, Zilei Wang^{1

4}, Hua Zhu^{1

2}, Zhi Yang^{1

2}

Affiliations

¹ Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), NMPA Key Laboratory for Research and Evaluation of Radiopharmaceuticals (National Medical Products Administration), Department of Nuclear Medicine, Peking University Cancer Hospital and Institute, Beijing 100142, China.
² Institute of Biomedical Engineering, Peking University Shenzhen Graduate School, Shenzhen, Guangdong 518055, China.
³ Guizhou University School of Medicine, Guiyang, Guizhou 550025, People's Republic of China.
⁴ Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China.

PMID: 35904514
DOI: 10.1021/acs.molpharmaceut.2c00342

Abstract

Mesothelin (MSLN) is a molecular biomarker of many types of solid tumors, such as mesothelioma, pancreatic cancer, and colon cancer. Owing to the significant difference in expression between cancer cells and normal cells, mesothelin has been widely used as a key target in cancer immunotherapy. In this study, we used iodine isotope (^nat/124/125I)-labeled mesothelin antibodies to noninvasively detect MSLN expression in mice with LS174T colon cancer. The ¹²⁴I-labeled MSLN antibody showed a high radiochemical purity (RCP, >99%) and specific activity (20.8-67.8 GBq/μmol) after purification and was stable in 5% HSA and PBS (>95% RCP at 8 days). Western blot analysis indicated that the LS174T cells showed a higher MSLN protein level than the HepG2 cells. The half maximal effective concentration (EC₅₀) values of the MSLN antibody and ^natI-anti-MSLN were 34.77 ± 3.72 ng/mL and 32.60 ± 2.52 ng/mL (P = 0.63), respectively. The dissociation constant of ¹²⁴I-anti-MSLN binding to MSLN protein was 16.0 nM. The radiotracer showed a significantly higher uptake in LS174T cells than in HepG2 tumor cells (1.56 ± 0.09 vs 0.81 ± 0.03, P = 0.0016) 2 days postinjection. The LS174T mouse models showed extremely low organ uptake and high tumor uptake 96 h after the injection of ¹²⁴I-anti-MSLN, and the T/M values were much higher than those of the other imaging groups (10.56 ± 1.20 for ¹²⁴I-anti-MSLN in LS174T mice vs 3.27 ± 0.20 for ¹²⁴I-anti-MSLN in HepG2 mice vs 3.53 ± 0.2 for ¹²⁴I-IgG in LS174T mice). The immunochemical histology results showed that LS174T tumors were strongly positive (+++) for MSLN, while those in the HepG2 group showed slight expression (+). The dosimetry estimation study showed that the effective dose of ¹²⁴I-anti-MSLN was 0.185 mSv/MBq, which is within the range of acceptable doses for further nuclear medicine translational research. Taken together, these results suggest that this radiotracer has the potential for detecting mesothelin-overexpressing tumors.

Keywords: colon cancer; iodine isotope; mesothelin; positron emission tomography.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cell Line, Tumor
Colonic Neoplasms*
GPI-Linked Proteins / metabolism
Immunoglobulin G
Iodine Radioisotopes
Mesothelin*
Mice

Substances

GPI-Linked Proteins
Immunoglobulin G
Iodine Radioisotopes
Iodine-124
Mesothelin