Discovery of a Selective Kinase Inhibitor (TAK-632) Targeting Pan-RAF Inhibition: Design, Synthesis, and Biological Evaluation of C-7-Substituted 1,3-Benzothiazole Derivatives

作者：Okaniwa Masanori^*; Hirose Masaaki; Arita Takeo; Yabuki Masato; Nakamura Akito; Takagi Terufumi; Kawamoto Tomohiro; Uchiyama Noriko; Sumita Akihiko; Tsutsumi Shunichirou; Tottori Tsuneaki; Inui Yoshitaka; Sang Bi Ching; Yano Jason; Aertgeerts Kathleen; Yoshida Sei; Ishikawa Tomoyasu

来源：Journal of Medicinal Chemistry, 2013, 56(16): 6478-6494.

DOI：10.1021/jm400778d

With the aim of discovering a selective kinase inhibitor targeting pan-RAF kinase inhibition, we designed novel 1,3-benzothiazole derivatives based on our thiazolo[5,4-b]pyridine class RAF/VEGFR2 inhibitor 1 and developed a regioselective cyclization methodology for the C-7-substituted 1,3-benzothiazole scaffold utilizing meta-substituted anilines. Eventually, we selected 7-cyano derivative 8B (TAK-632) as a development candidate and confirmed its binding mode by cocrystal structure with BRAF. Accommodation of the 7-cyano group into the BRAF-selectivity pocket and the 3-(trifluoromethyl)phenyl acetamide moiety into the hydrophobic back pocket of BRAF in the DFG-out conformation contributed to enhanced RAF potency and selectivity vs VEGFR2. Reflecting its potent pan-RAF inhibition and slow off-rate profile, 8B demonstrated significant cellular activity against mutated BRAF or mutated NRAS cancer cell lines. Furthermore, in both A375 (BRAF(V600E))and HMVII (NRAS(Q61K)) xenograft models in rats, 8B demonstrated regressive antitumor efficacy by twice daily, 14-day repetitive administration without significant body weight loss.

• 出版日期2013-8-22