A new human antitumor immunoreagent specific for ErbB2.
OBJECTIVE
Our aim was to isolate a novel human mini-antibody(scFv) that specifically targets ErbB2-positive cancer cells. ErbB2, a tyrosinekinase receptor, is overexpressed in clinically significant tumors, such as breast, ovary, and lung carcinomas. In normal tissues, it is expressed only in certain epithelial cell types.


METHODS
A large phagemid library (Griffin.1 library) of human scFv was used for the isolation of the ErbB2-specific scFv. A very effective strategy was developed for the isolation, consisting in a double subtractive selection, the use of two different combinations of "positive," i.e., ErbB2-bearing, and "negative" cell lines.


RESULTS
Here we report the isolation of the first human anti-ErbB2 mini-antibody endowed with antitumor action. Both in its soluble and phage format, it binds specifically to ErbB2, inhibits its autophosphorylation, is internalized by target cells, and exerts a strong and specific antiproliferative action on ErbB2-positive target cells. A correlation was found between the extent of this antiproliferative effect and the expression levels of ErbB2 on target cells, with a strong cytotoxicity for hyper-expressing cells, such as SKBR3, in which apoptosis was evidenced.


CONCLUSIONS
This scFv is a potentially effective immunoreagent for diagnostics and therapeutics of certain cancers, both as a readily diffused molecule in solid tumors and as an essential asset for the construction of fully human anticancer drugs.
De Lorenzo
Claudia
C
Department of Biological Chemistry, University of Naples Federico II, via Mezzocannone 16, 80134 Naples, Italy.
Palmer
Donald B
DB
Piccoli
Renata
R
Ritter
Mary A
MA
D'Alessio
Giuseppe
G
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D001435:Bacteriophages / Q000235:genetics; D001943:Breast Neoplasms / Q000628:therapy*; D002455:Cell Division / Q000187:drug effects; D003001:Cloning, Molecular; D004705:Endocytosis; D005260:Female; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000276:immunology; D051379:Mice; D010766:Phosphorylation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D014407:Tumor Cells, Cultured / Q000166:cytology; D014443:Tyrosine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007135:Immunoglobulin Variable Region; D018719:Erb-b2 Receptor Tyrosine Kinases; D014443:Tyrosine