Design and Synthesis of Novel DFG-Out RAF/Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) Inhibitors. 1. Exploration of [5,6]-Fused Bicyclic Scaffolds
作者:Masanori Okaniwa、Masaaki Hirose、Takashi Imada、Tomohiro Ohashi、Youko Hayashi、Tohru Miyazaki、Takeo Arita、Masato Yabuki、Kazuyo Kakoi、Juran Kato、Terufumi Takagi、Tomohiro Kawamoto、Shuhei Yao、Akihiko Sumita、Shunichirou Tsutsumi、Tsuneaki Tottori、Hideyuki Oki、Bi-Ching Sang、Jason Yano、Kathleen Aertgeerts、Sei Yoshida、Tomoyasu Ishikawa
DOI:10.1021/jm300126x
日期:2012.4.12
To develop RAF/VEGFR2 inhibitors that bind to the inactive DFG-out conformation, we conducted structure-based drug design using the X-ray cocrystal structures of BRAF, starting from an imidazo[1,2-b]pyridazine derivative. We designed various [5,6]-fused bicyclic scaffolds (ring A, 1-6) possessing an anilide group that forms two hydrogen bond interactions with Cys532. Stabilizing the planarity of this anilide and the nitrogen atom on the six-membered ring of the scaffold was critical for enhancing BRAF inhibition. The selected [1,3]thiazolo[5,4-b]pyridine derivative 6d showed potent inhibitory activity in both BRAF and VEGFR2. Solid dispersion formulation of 6d (6d-SD) maximized its oral absorption in rats and showed significant suppression of ERK1/2 phosphorylation in an A375 melanoma xenograft model in rats by single administration. Tumor regression (T/C = -7.0%) in twice-daily repetitive studies at a dose of 50 mg/kg in rats confirmed that 6d is a promising RAF/VEGFR2 inhibitor showing potent anticancer activity.