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To explore mechanisms underlying a 57% relative risk reduction of major adverse cardiovascular events (MACE) in type 2 diabetes mellitus (T2DM) patients (pts) with CVD given 200 mg apabetalone (APL) by mouth. APL is a small molecule that inhibits bromodomain and extra-terminal (BET) proteins, which are epigenetic readers of acetylated lysine in histones contained within actively transcribing chromatin. Inhibiting BET proteins attenuates transcribed genes that are upregulated in disease states. Studies here used SOMAscan proteomics of patient plasma given placebo (n=30) or APL (n=25) and cultured monocyte (THP-1) or endothelial (HUVEC) cells. Results showed differences in the proteome spanning 4 CVD pathways: acute phase response, intrinsic prothrombin activation, leukocyte extravasation signaling, and coagulation. This data showed TNFα target genes were preferentially upregulated in T2DM+CVD (p50%. HG induced adhesion genes in HUVECs, E-selectin and MYD88, by 2- and 1.3-fold was lowered by APL. In summary, APL lowers MACE in T2DM+CVD pts by attenuating expression of genes that mediate adhesion of monocytes to endothelial cells. This hypothesis is being tested in a phase 3 trial BETonMACE. Disclosure L. Tsujikawa: None. E. Kulikowski: Employee; Self; Resverlogix Corp. Stock/Shareholder; Self; Resverlogix Corp. C. Calosing: None. S. Wasiak: Employee; Self; Resverlogix Corp. Stock/Shareholder; Self; Resverlogix Corp. D. Gilham: Employee; Self; Resverlogix Corp. C. Halliday: Employee; Self; Resverlogix Corp. Stock/Shareholder; Self; Resverlogix Corp. J.O. Johansson: Employee; Self; Resverlogix Corp. M. Sweeney: Employee; Self; Resverlogix Corp. N.C. Wong: Employee; Self; Resverlogix Corp. Stock/Shareholder; Self; Resverlogix Corp.

Apabetalone (RVX-208) leads to a 57% relative risk reduction of MACE in patients with diabetes mellitus (DM) and CVD. To test whether RVX-208, an inhibitor (BETi) of epigenetic readers bromodomain extra-terminal (BET) proteins lowers CVD by affecting genes mediating monocyte adhesion to endothelial cells in response to high glucose(HG) and dietary metabolite trimethyl-amine oxide (TMAO). Cultured THP-1 monocytes, HUVEC endothelial cells and primary human hepatocytes (PHH) were exposed to varying amts of glucose and TMAO. Results showed that HG (25.6 mM) induced Very Late Antigen-4 (VLA-4) mRNA, a gene mediating THP-1 adhesion by 1.3-fold and RVX-2suppressed it >50%. BETi blocked TMAO induction of VLA-4 mRNA by >50% in THP-1. In HUVECs RVX-2abrogated HG induction of E-selectin and MYD88 mRNA by 2- and 1.3-fold, respectively and lowered TMAO induction of both mRNAs by >50%. Microbiome action on dietary phospholipids followed by hepatic flavin mono-oxygenase-3 (FMO3) processing yields TMAO. In PHH exposed for 24 hours to RVX-208, FMO3 mRNA was lower by 40% but it also suppressed a transcriptional regulator of FMO3, farnesoid X receptor (FXR). BETi for 6 hours suppressed both FXR mRNA and protein within 6 hours by >80% suggesting a direct effect of BETi on the FXR gene. Furthermore, in ChiP assays BRD4, a BET protein, dissociated immediately from FXR DNA upon exposure to RVX-208. BRD4 guides a complex containing RNA pol II along active genes, its dissociation would halt transcription of the gene. In summary, Apabetalone inhibits HG and TMAO enhanced adhesion of THP-1 to HUVECs, this process mimics a step in CVD pathogenesis. RVX-2suppresses cellular adhesion genes; VLA-4 in THP-1 and both E-selectin plus MYD88 in HUVECs. BETi blocks TMAO activity and its production by inhibiting FXR expression, a regulator of FMO3 gene transcription. Rapid actions of BETi in dissociating BRD4 from FXR DNA suggests a direct effect of RVX-2on transcription of this gene. Disclosure L. Tsujikawa: None. E. Kulikowski: Employee; Self; Resverlogix Corp.. C. Calosing: None. S. Wasiak: Employee; Self; Resverlogix Corp. D. Gilham: Employee; Self; Resverlogix Corp.. Stock/Shareholder; Self; Resverlogix Corp.. C. Halliday: None. J.O. Johansson: Employee; Self; Resverlogix Corp., Artery Therapeutics, Inc. M. Sweeney: Employee; Self; Resverlogix Corp. N.C. Wong: Stock/Shareholder; Self; Resverlogix Corp..