posted on 2023-11-21, 16:20authored byZilei Wang, Chuanke Zhao, Jin Ding, Yan Chen, Jiayue Liu, Xingguo Hou, XiangXing Kong, Bin Dong, Zhi Yang, Hua Zhu
Recent global clinical trials have
shown that CLDN18.2 is an ideal
target for the treatment of gastric cancer and that patients with
high CLDN18.2 expression can benefit from targeted therapy. Therefore,
accurate and comprehensive detection of CLDN18.2 expression is important
for patient screening and guidance in anti-CLDN18.2 therapy. Phage
display technology was used to screen CLDN18.2-specific peptides from
100 billion libraries. 293TCLDN18.1 cells were used to
exclude nonspecific binding and CLDN18.1 binding sequences, while
293TCLDN18.2 cells were used to screen CLDN18.2-specific
binding peptides. The monoclonal clones obtained from phage screening
were sequenced, and peptides were synthesized based on the sequencing
results. Binding specificity and affinity were assessed with a fluorescein
isothiocyanate (FITC)-conjugated peptide. A 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid (DOTA)-conjugated peptide was also synthesized for 68Ga radiolabeling. The in vitro and in vivo stability, partition coefficients, in vivo molecular
imaging, and biodistribution were also characterized. Overall, 54
monoclonal clones were selected after phage display screening. Subsequently,
based on the cell ELISA results, CLDN18.2 preference monoclonal clones
were selected for deoxyribonucleic acid (DNA) sequencing, and four
7-peptide sequences were obtained after sequence comparison; among
them, a peptide named T37 was further validated in vitro and in vivo. The T37 peptide specifically recognized
CLDN18.2 but not CLDN18.1 and bound strongly to CLDN18.2-positive
cell membranes. The 68Ga-DOTA-T37 probe exhibits good in vitro properties and high stability as a hydrophilic
probe; it has high biological safety, and positron emission tomography/computed
tomography (PET/CT) studies have shown that it can specifically target
CLDN18.2 protein and CLDN18.2-positive tumors in mice. 68Ga-DOTA-T37 demonstrated the superiority and feasibility of using
a CLDN18.2-specific probe in PCT/CT imaging, which deserves further
development and exploitation.