A human monoclonal antibody against insulin-like growth factor-II blocks the growth of human hepatocellular carcinoma cell lines in vitro and in vivo.
Elevated expression of insulin-like growth factor-II (IGF-II) is frequently observed in a variety of human malignancies, including breast, colon, and liver cancer. As IGF-II can deliver a mitogenic signal through both IGF-IR and an alternately spliced form of the insulin receptor (IR-A), neutralizing the biological activity of this growth factor directly is a potential alternative option to IGF-IR-directed agents. Using a Fab-displaying phage library and a biotinylated precursor form of IGF-II (1-104 amino acids) as a target, we isolated Fabs specific for the E-domain COOH-terminal extension form of IGF-II and for mature IGF-II. One of these Fabs that bound to both forms of IGF-II was reformatted into a full-length IgG, expressed, purified, and subjected to further analysis. This antibody (DX-2647) displayed a very high affinity for IGF-II/IGF-IIE (K(D) value of 49 and 10 pmol/L, respectively) compared with IGF-I (approximately 10 nmol/L) and blocked binding of IGF-II to IGF-IR, IR-A, a panel of insulin-like growth factor-binding proteins, and the mannose-6-phosphate receptor. A crystal complex of the parental Fab of DX-2647 bound to IGF-II was resolved to 2.2 A. DX-2647 inhibited IGF-II and, to a lesser extent, IGF-I-induced receptor tyrosine phosphorylation, cellular proliferation, and both anchorage-dependent and anchorage-independent colony formation in various cell lines. In addition, DX-2647 slowed tumor progression in the Hep3B xenograft model, causing decreased tumoral CD31 staining as well as reduced IGF-IIE and IGF-IR phosphorylation levels. Therefore, DX-2647 offers an alternative approach to targeting IGF-IR, blocking IGF-II signaling through both IGF-IR and IR-A.
Discovery Research, Dyax Corp., Cambridge, Massachusetts 02139, USA. ddransfield@dyax.com
Daniel T
DT
Dransfield
Edward H
EH
Cohen
Qing
Q
Chang
Lindsay G
LG
Sparrow
John D
JD
Bentley
Olan
O
Dolezal
Xiaowen
X
Xiao
Thomas S
TS
Peat
Janet
J
Newman
Patricia A
PA
Pilling
Tram
T
Phan
Ilka
I
Priebe
Gemma V
GV
Brierley
Niksa
N
Kastrapeli
Kris
K
Kopacz
Diana
D
Martik
Dina
D
Wassaf
Douglas
D
Rank
Greg
G
Conley
Yan
Y
Huang
Timothy E
TE
Adams
Leah
L
Cosgrove
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000627:therapeutic use*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018450:Disease Progression; D006801:Humans; D007150:Immunohistochemistry; D007335:Insulin-Like Growth Factor II / Q000276:immunology*; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D051379:Mice; D015398:Signal Transduction / Q000187:drug effects; D014410:Tumor Stem Cell Assay; D023041:Xenograft Model Antitumor Assays
D000911:Antibodies, Monoclonal; D007335:Insulin-Like Growth Factor II