Development of BET Inhibitors as Potential Treatments for Cancer: Optimization of Pharmacokinetic Properties.

We describe the synthesis of triazole-containing carboline derivatives and their utility as bromodomain and extra-terminal (BET) inhibitors. A convergent synthetic route permitted the detailed investigation of deuteration and fluorination strategies to reduce clearance while maintaining a favorable in vitro profile. This work led to the identification of a potent BET inhibitor, 2-{8-fluoro-3-[4-( 2 H 3 )methyl-1-methyl-1 H -1,2,3-triazol-5-yl]-5-[( S )-(oxan-4-yl)(phenyl)methyl]-5 H -pyrido[3,2- b ]indol-7-yl}propan-2-ol ( 15 ), which demonstrated reduced clearance and an improved pharmacokinetic (PK) profile across preclinical species. Importantly, no major metabolite was observed when 15 was incubated with human hepatocytes (hHEP) for 2 h. This study culminated with the evaluation of 15 in a mouse triple-negative breast cancer (TNBC) tumor model where it demonstrated robust efficacy at low doses.