ABSTRACT
Epithelial cell adhesion molecule (EpCAM) is a popular target for cancer therapy. In this research, 3 nanobodies with high specificity and endocytosis activity against EpCAM were developed, which provides a basis for the study of immunotoxin based on EpCAM. In our preliminary experiments, we have immunized a camel with EpCAM-Fc antigen and constructed a high-quality phage display library. Seventeen nanobodies with different complementarity determining region (CDR) 3 sequences have been screened after 3 rounds of biopanning by phage display technology. The animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of Fudan University School of Pharmacy. After purification, 7 nanobodies showed high cell binding activity by fluorescent activated cell sorting (FACS) identification. Furthermore, 3 nanobodies presented high endocytosis activity based on FACS and laser confocal microscopy, which also showed high affinity to EpCAM measured by ForteBio. According to this study, we aimed to provide a novel alternative approach to the EpCAM-targeted therapy and to provide guidance for the study of nanobody based immunotoxins for other targets.
ABSTRACT
Immunotherapy is a new strategy for cancer treatment that has the potential to treat all types of cancer. T cell immunoglobulin and mucin-domain-containing molecule-3 (TIM-3) is a key negative regulator of T cell activation. TIM-3 blockage using anti-TIM-3 monoclonal antibody therapy has a great appeal and special advantages. Nanobodies, derived from heavy chain fragment in camelid animals, are now proving clinical values in the development of antibody drugs. In this study, we have immunized camel with TIM-3 antigens and then constructed phage display library. Moreover, 29 nanobodies with different complementarity-determining regions sequences have been screened from the phage display library by phage display technology. In addition, we successfully constructed the cell line stably expressing TIM-3, and screened 10 TIM-3 nanobodies with high specificity and high affinity using flow cytometry. Our study will lay the foundation for the future screening and development of anti-TIM-3 whole humanized functional nanobody.