GDC-0879

GDC-0879 (AR00341677) is an orally active, ATP site-targeting, highly potent Raf inhibitor (IC50 against V600E B-Raf-catalyzed MEK phophorylation = 0.13 nM with 4 μM ATP; IC50 against pERK in V600E B-Raf-expressing cells = 29 nM/Colo205, 59 nM/A375, 63 nM/Malme-3M) with great selectivity over >200 protein kinases (IC50 >1 μM). Oral administration is shown to effectively suppress Colo205 and A375 xenografts-derived tumor growth and pMEK1 in mice in vivo (35 mg/kg bid; 50-200 mg/kg qd or bid). Paradoxically, GDC-0879 also induces wild-type and enhances V600E B-Raf dimerization in an allosteric manner independent of kinase activity inhibition, resulting in selective anti-proliferation activity against V600E B-Raf cancer cells, but not in KRAS mutant or RAS/WT Raf cells, where GDC-0879 induces formation of B–C and A–B heterodimers and downstream signaling activation.