ATVB abstract embargo is now released.

Oral Presentation May 4, 2017, 4:45 - 5:00 PM

Selective BET Inhibitors Are Useful for Normalizing Inflammation Leading to Reduced Cardiovascular Disease (CVD) in Humans

Apabetalone (RVX-208) a bromodomain extra-terminal (BET) inhibitor selectively binds the 2nd ligand domain within a BET protein thus displacing it from acetylated lysine marks on histone tails. In clinical trials of ~1000 patients, many (n=499) of whom with CVD when given 200 mg/d RVX-208 had a 55% relative risk reduction in major adverse cardiac events (MACE) vs placebo. This benefit of RVX-208 may stem from ability of BET inhibition (BETi) to calm inflammation, metabolism, coagulation and complement pathways with well-known roles in CVD risks. These potential benefits of RVX-208 underlie BETonMACE a phase 3 CVD events trial. Of major interest is the anti-inflammatory (AI) effects seen in clinical data showing BETi lowers CRP by 28% in RVX-208 treated patients (n=331). RVX-208 lowered IL-6 and MCP-1 U937 cells exposed to LPS in a dose and time dependent manner by 90 and 85%, respectively within 24 hrs. RVX-208 displaced BET proteins BRD2-4 from chromatin. These AI effects underpin studies of RVX-297 a more potent cousin of RVX-208 that lowered IL-6 and MCP-1 in LPS stimulated U937 cells by 95 and 80% respectively within 24 hrs. In ChIP assays, RVX-297 also displaced BET protein BRD4 and pol II from promoters of cytokine genes IL-6 and IL-1β that mediate inflammation. Together, data from studying RVX-208 and -297 show both BET inhibitors displace transcription factors from promoter DNA that control expression of inflammatory genes (IGs) with key roles in CVD. Importance of BETi displacement of BRD4 and pol II from DNA becomes clear when added to the fact that cellular response to inflammation requires immediate and robust expression of defined set of IGs. For this rapid transcriptional response, the cell places chromatin structures upstream of IGs called super-enhancers (SE) or latent enhancers (LE) that act as molecular sinks for attracting BET proteins such as BRD4. The placement of a SE or LE adjacent to a promoter that controls a IG recruits this gene to the response against an inflammatory insult. Thus targeting BET proteins including BRD4 with a selective BETi may have broad effects on many genes or pathways by crippling SE or LE mediated cellular response to the inflammatory component of CVD. This mechanism may have potential implications to other inflammatory diseases.

Poster Presentation May 6, 2017, 8:30 - 10:30 AM

Apabetalone (Rvx-208), a Selective Bet Protein Inhibitor, Reduces Expression of Acute Phase Response Markers in vitro and in Patients With Cardiovascular Disease and Chronic Kidney Disease

Apabetalone is an inhibitor of the epigenetic readers bromodomain and extraterminal (BET) proteins, currently in a phase 3 outcomes trial in patients with cardiovascular disease (CVD) and diabetes mellitus. A post hoc analysis of phase 2b trials demonstrated a 55% relative risk reduction in major adverse cardiac events in CVD patients. Elevated inflammatory markers correlate with CVD. Inflammation also accompanies chronic kidney disease (CKD) and CKD patients are at risk of CVD. Previous research has shown that apabetalone modulates pathways that contribute to chronic inflammation, including the acute phase response (APR). Here, pathway analysis of gene microarrays showed downregulation of APR by apabetalone in primary human hepatocytes (PHH). Real-time PCR and ELISA analysis of RVX-208 treated PHHs confirmed that APR genes that correlate with CVD are suppressed by 20 to 95%, including CRP, ceruloplasmin (CP), serum amyloid P (SAP), PAI-1, alpha 2-macroglobulin (A2M), complement C2, C3 and C5, MBL2, serum amyloid A and interleukin 18. Apabetalone decreased IL-6-induced expression of CP, SAP and A2M, with most striking effects on CRP (-75%). Apabetalone also decreased LPS-induced expression of SAP in a mouse endotoxemia model. To assess effects of apabetalone on inflammatory mediators in CVD patients, SOMAscan™ 1.3K proteomic analysis was performed on plasma from phase 2b ASSERT (12 weeks; n=25) and ASSURE (26 weeks; n=47) clinical trials. This approach identified APR as the top downregulated pathway by apabetalone in both trials. APR biomarkers are elevated in CKD patients where they correlate with disease progression. To gain insight into the pharmacodynamics of the APR response to apabetalone, stage 4 CKD patients (n=8) received a single dose of the drug followed by plasma proteomics at several time points. At 12h post dose, APR was significantly downregulated by apabetalone. Of note, CRP was decreased in CKD patients after 12h of treatment (-7%, p=0.04) versus baseline, as well as in ASSERT (-43%, p=0.01) and ASSURE (-21%, p=0.02) trials versus placebo. Downregulation of the APR pathway by apabetalone may lead to reduced chronic inflammation in CVD and CKD patients and contribute to the reduction in MACE in patients with high residual CVD risk.