In vitro activity: AZ628 prevents activation of number of tyrosine protein kinases including VEGFR2, DDR2, Lyn, Flt1, FMS and others. AZ628 suppresses anchorage-dependent and -independent growth, gives rise to cell cycle arrest, and induces apoptosis in colon and melanoma cell lines harboring B-RafV600E mutation. The profile of AZ628 cross-reactivity suggests that similar to sorafenib, AZ628 may be antiangiogenic based on prevention of VEGFR2. AZ628-resistant clones are approximately 100-fold more resistant to AZ628 than the parental cell line, exhibiting IC50 of approximately 10 μM, compared with 0.1 μM for the parental cell line. Effective suppression of p-ERK1/2 levels is observed in the M14 parental cell line following treatment with increasing concentrations of AZ628. AZ628-resistant clones express elevated CRAF. Elevated CRAF expression is a potential mechanism of acquired resistance to continuous AZ628 exposure, resulting in sustained activation of ERK1/2. p-ERK1/2 activity is not significantly inhibited by exposure to AZ628 in one of these three AZ628-insensitive cell lines (Wm1552C). Unlike in the AZ628-resistant M14 cells in which AZ628 fails to suppress the activation of ERK, AZ628 treatment efficiently attenuates ERK activation in the NRAS mutant melanoma cells.

Kinase Assay: AZ 628 is a pan-Raf kinase inhibitor with IC50s of 105, 34 and 29 nM for B-Raf, B-RafV600E, and c-Raf-1, respectively.

Cell Assay: Approximately 0.5-2.5 × 105 M14 cells (M14 expressing the V600E BRAF mutation) are seeded in 12 or 24 - well plates, respectively, in medium supplemented with 5% FBS. After overnight incubation, the cells are treated with various concentrations of AZ628. Fresh medium and drug is replaced every 2 days until the untreated control wells reached confluence. At this time-point, the media is removed and the cells are fixed in 4% formaldehyde in PBS for 20 minutes at room temperature. Cells are then washed twice with PBS and stained with a 1:5000 solution of the fluorescent nucleic acid stain Syto60. Quantitation of fluorescent signal intensity is carried out at 700 nm, using an Odyssey Infrared Imager. Each experiment is performed in quadruplicate and the results shown represent the average of the four values compared to untreated wells. Error bars represent standard deviation of the 4 values from the mean. High-throughput cell growth/viability assays are performed.

Expert Opin Ther Targets. 2007 Dec;11(12):1587-609; Cancer Res. 2008 Jun 15;68(12):4853-61.