A novel, potent, and selective insulin-like growth factor-I receptor kinase inhibitor blocks insulin-like growth factor-I receptor signaling in vitro and inhibits insulin-like growth factor-I receptor–dependent tumor growth in vivo

• Published in: Molecular cancer therapeutics Vol. 6; no. 8; pp. 2158 - 2167
• Main Authors: Ji, Qun-sheng, Mulvihill, Mark J, Rosenfeld-Franklin, Maryland, Cooke, Andrew, Feng, Lixin, Mak, Gilda, O'Connor, Matthew, Yao, Yan, Pirritt, Caroline, Buck, Elizabeth, Eyzaguirre, Alexandra, Arnold, Lee D, Gibson, Neil W, Pachter, Jonathan A
• Format: Journal Article
• Language: English
• Published: United States American Association for Cancer Research 01.08.2007
• Subjects: Animals; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacokinetics; Antineoplastic Agents - pharmacology; Autocrine Communication - drug effects; Autocrine-paracrine signaling; Blood Glucose - drug effects; Cell Line, Tumor; Cell Proliferation - drug effects; Colorectal Neoplasms - pathology; Enzyme Activation - drug effects; Female; Humans; Imidazoles - administration & dosage; Imidazoles - chemistry; Imidazoles - pharmacokinetics; Imidazoles - pharmacology; Insulin-Like Growth Factor II - metabolism; Mice; Mice, Nude; Phosphorylation - drug effects; Protein Kinase Inhibitors - administration & dosage; Protein Kinase Inhibitors - chemistry; Protein Kinase Inhibitors - pharmacokinetics; Protein Kinase Inhibitors - pharmacology; Protein tyrosine kinases; Pyrazines - administration & dosage; Pyrazines - chemistry; Pyrazines - pharmacokinetics; Pyrazines - pharmacology; Receptor, IGF Type 1 - antagonists & inhibitors; Receptor, IGF Type 1 - metabolism; Signal Transduction - drug effects; Small Molecules and Other Therapeutics Agents; Tumor Stem Cell Assay; Xenograft Model Antitumor Assays
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-07-0070

Insulin-like growth factor-I receptor (IGF-IR) and its ligands, IGF-I and IGF-II, are up-regulated in a variety of human cancers. In tumors, such as colorectal, non–small cell lung, ovarian, and pediatric cancers, which may drive their own growth and survival through autocrine IGF-II expression, the role of IGF-IR is especially critical. Here, we present a novel small-molecule IGF-IR kinase inhibitor, cis -3-[3-(4-methyl-piperazin-l-yl)-cyclobutyl]-1-(2-phenyl-quinolin-7-yl)-imidazo[1,5- a ]pyrazin-8-ylamine (PQIP), which displayed a cellular IC 50 of 19 nmol/L for inhibition of ligand-dependent autophosphorylation of human IGF-IR with 14-fold cellular selectivity relative to the human insulin receptor. PQIP showed minimal activity against a panel of 32 other protein kinases. It also abolished the ligand-induced activation of downstream phosphorylated AKT and phosphorylated extracellular signal-regulated kinase 1/2 in both IGF-IR transfectant cells and a GEO human colorectal cancer cell line. Analysis of GEO cells revealed a significant level of both phosphorylated IGF-IR and IGF-II expression. Furthermore, inactivation of IGF-II in conditioned GEO culture medium by a neutralizing antibody diminished IGF-IR activation, indicating the presence of a functional IGF-II/IGF-IR autocrine loop in GEO cells. Once daily oral dosing of PQIP induced robust antitumor efficacy in GEO xenografts. The antitumor efficacy correlated with the degree and duration of inhibition of tumor IGF-IR phosphorylation in vivo by this compound. Moreover, when mice were treated for 3 days with a dose of PQIP that maximally inhibited tumor growth, only minor changes in blood glucose were observed. Thus, PQIP represents a potent and selective IGF-IR kinase inhibitor that is especially efficacious in an IGF-II–driven human tumor model. [Mol Cancer Ther 2007;6(8):2158–67]