title: Isolation of functional single domain antibody by whole cell immunization: implications for cancer treatment.
abstract: Carcinoembryonic antigen related cell adhesion molecule (CEACAM) 6 is over-expressed in different types of cancer cells. In addition, it has also been implicated in some infectious diseases. Targeting this molecule by an antibody might have applications in diverse tumor models. Single domain antibody (sdAb) is becoming very useful format in antibody engineering as potential tools for treating acute and chronic disease conditions such as cancer for both diagnostic as well as therapeutic application. Generally, sdAbs with good affinity are isolated from an immune library. Discovery of a new target antigen would require a new immunization with purified antigen which is not always easy. In this study, we have isolated, by phage display, an sdAb against CEACAM6 with an affinity of 5 nM from a llama immunized with cancer cells. The antibody has good biophysical properties, and it binds to the cells expressing the target antigen. Furthermore, it reduces cancer cells proliferation in vitro and shows an excellent tumor targeting in vivo. This sdAb could be useful in diagnosis as well as therapy of CEACAM6 expressing tumors. Finally, we envisage it would be feasible to isolate good sdAbs against other interesting tumor associated antigens from this library. Therefore, this immunization method could be a general strategy for isolating sdAbs against any surface antigen without immunizing the animal with the antigen of interest each time.
authors: Antibody Engineering, Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada. toyanath.baral@nrc-cnrc.gc.ca
authors: Toya Nath
authors: TN
authors: Baral
authors: Yanal
authors: Y
authors: Murad
authors: Thanh-Dung
authors: TD
authors: Nguyen
authors: Umar
authors: U
authors: Iqbal
authors: Jianbing
authors: J
authors: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000912:Antibodies, Neoplasm / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000627:therapeutic use; D000915:Antibody Affinity; D015703:Antigens, CD / Q000008:administration & dosage / Q000276:immunology; D000951:Antigens, Neoplasm / Q000008:administration & dosage / Q000276:immunology; D001483:Base Sequence; D002161:Camelids, New World; D015815:Cell Adhesion Molecules / Q000008:administration & dosage / Q000276:immunology; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D018604:Epitope Mapping; D058851:GPI-Linked Proteins / Q000008:administration & dosage / Q000276:immunology; D006801:Humans; D007114:Immunization; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000276:immunology / Q000628:therapy; D019151:Peptide Library; D015202:Protein Engineering / Q000379:methods; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000627:therapeutic use*
chemical_list: D000912:Antibodies, Neoplasm; D015703:Antigens, CD; D000951:Antigens, Neoplasm; C504117:CEACAM6 protein, human; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D058851:GPI-Linked Proteins; D019151:Peptide Library; D057127:Single-Chain Antibodies