5-[(4-Bromo-2-chlorophenyl)amino]-4-fluoro-N-(2-hydroxyethoxy)-1-methyl-1H-benzimidazole-6-carboxamide

inhibitor of MEK1/2 kinases, effectively inhibited the proliferation of acute biphenotypic leukemia MV4-11 and acute monocytic leukemia MOLM13 cells. The concentrations that inhibited 50% growth were approximately 0.3 and 1.2 µM, respectively, as measured by thymidine uptake on day 2 of culture. AZD6244 potently down-regulated the levels of phospho-ERK1/2 and its downstream effector, p-p70S6K, in the MV4-11 and MOLM13 cells as measured by Western blot analysis. Four BRAF mutant lines exhibited growth inhibition at low doses of the drug, with GI50 concentrations ranging from 14 to 50 nM, predominantly via a G0/G1 arrest, comparable with findings in a sensitive BRAF mutant melanoma cell line. In contrast, two BRAF wild-type lines were significantly less sensitive, with GI50 values greater than 200 nM. Nude mouse xenograft tumors derived from the BRAF mutant line ARO exhibited dosedependent growth inhibition by AZD6244, with effective treatment at 10 mg/kg by oral gavage. This effect was primarily cytostatic and associated with marked inhibition of ERK phosphorylation.

OTAVAchemicals Catalogue Number: 1183194
CAS Registry Number: 606143-52-6
Purity: 97%+ (HPLC)

Ref. 1: Revill et al. AZD-6244. Drugs of the Future (2006), 31, 854-858;

Abstract: The MEK/ERK-dependent mitogen-activated protein (MAP) kinase pathway mediates cellular responses to growth signals, and aberrant regulation of the pathway has been implicated in many human cancers.  Because of its key position as the only known activator of ERK, and its location downstream of the oncogenes ras and raf, MEK offers an attractive target for chemotherapeutic intervention. AZD-6244 (ARRY-142886) is an orally active, highly specific inhibitor of MEK that has shown tumor-suppressive activity in a wide range of preclinical models of human cancer. AZD-6244 is currently in phase II development for the treatment of melanoma, non-small cell lung and pancreatic cancer.

Ref. 2: Yeh et al. Biological Characterization of ARRY-142886 (AZD6244), a Potent, Highly Selective Mitogen-Activated Protein Kinase Kinase 1/2 Inhibitor. Clinical Cancer Research (2007), 13, 1576-1583

Abstract
Purpose: The Ras-Raf-mitogen-activated protein kinase kinase (MEK) pathway is overactive in many human cancers and is thus a target for novel therapeutics. We have developed a highly potent and selective inhibitor of MEK1/2. The purpose of these studies has been to show the biological efficacy of ARRY-142886 (AZD6244) in enzymatic, cellular, and animal models.
Experimental Design: The ability of ARRY-142886 to inhibit purified MEK1 as well as other kinases was evaluated. Its effects on extracellular signal-regulated kinase (ERK) phosphorylation and proliferation in several cell lines were also determined. Finally, the inhibitor was tested in HT-29 (colorectal) and BxPC3 (pancreatic) xenograft tumor models.
Results: The IC50 of ARRY-142886 was determined to be 14 nmol/L against purified MEK1. This activity is not competitive with ATP, which is consistent with the high specificity of compound for MEK1/2. Basal and epidermal growth factor–induced ERK1/2 phosphorylation was inhibited in several cell lines as well as 12-O-tetradecanoylphorbol-13-acetate–induced ERK1/2 phosphorylation in isolated peripheral blood mononuclear cells. Treatment with ARRY-142886 resulted in the growth inhibition of several cell lines containing B-Raf and Ras mutations but had no effect on a normal fibroblast cell line. When dosed orally, ARRY-142886 was capable of inhibiting both ERK1/2 phosphorylation and growth of HT-29 xenograft tumors in nude mice. Tumor regressions were also seen in a BxPC3 xenograft model. In addition, tumors remained responsive to growth inhibition after a 7-day dosing holiday.
Conclusions: ARRY-142886 is a potent and selective MEK1/2 inhibitor that is highly active in both in vitro and in vivo tumor models. This compound is currently being investigated in clinical studies.

DOI: 10.1158/1078-0432.CCR-06-1150